QCD@LHC 2026

28 Sept 2026, 08:00 → 2 Oct 2026, 13:00 Europe/London

University of Oxford

The 16th edition of QCD@LHC, aimed at fostering discussions and collaboration between experimenters and theorists working on strong interactions at the LHC, will be held at the University of Oxford, in the Department of Physics and St. Anne's College.

The workshop will will run from 9am on Monday 28 September to 1pm on Friday 2 October and consist of plenary and parallel sessions.

Scientific Programme

The parallel sessions will be on the following topics:

• Higgs, EW, BSM physics. Conveners: Alexander Karlberg (TH), Caterina Vernieri (ATLAS), Mika Vesterinen (LHCb) + Daniel Winterbottom (CMS)
• Heavy-quarks. Conveners: Chiara Savoini (TH), Riccardo Manzoni (CMS), Ivan Polyakov (LHCb) + Marcos Miralles Lopez (ATLAS)
• PDFs and DIS. Conveners: Thomas Cridge (TH), Gitanjali Poddar (ATLAS), Kenneth Long (CMS), Ciprian Gal (EIC)
• High-scale QCD. Conveners: Federico Buccioni (TH), Federico Sforza (ATLAS), Jennifer Roloff (CMS)
• Low-scale QCD, including heavy-ion physics. Conveners: Adam Takacs (TH), Alice Ohlson (ALICE), Ynyr Harris (ATLAS), Georgios Krintiras (CMS), Imanol Corredoira (LHCb)
• New techniques, tools and generators. Conveners: Emanuele Re (TH), Frank Siegert (ATLAS), Kyle Cormier (CMS)

Confirmed theory plenary speakers are Simon Badger, Stefano Forte, Marina Marinkovic, Guilherme Milhano, Tilman Plehn, Laura Reina, Steffen Schumann, Chiara Signorile-Signorile, Wouter Waalewijn, James Whitehead.

There will also be a panel discussion on the value of the strong coupling constant, with David d'Enterria, Alberto Ramos and Giulia Zanderighi as panellists.

Schedule

	Monday	Tuesday	Wednesday	Thursday	Friday
morning	plenary	plenary	plenary	parallel	plenary
afternoon	parallel	parallel	free	parallel
evening	reception			dinner

Registration and abstract submission

Registration and abstract submission are expected to open in April. Deadlines will be

• 1 July for abstract submission, now extended to 15 July
• 2 August for early registration (fee of £350), now extended to 16 August
• 4 September for final registration (fee of £380)

The registration fee will include the cost of lunches (Monday-Thursday), the reception and conference dinner. Thanks to support from the IPPP (Durham), we are able to offer a reduced fee for PhD students, of £300 for early registration (£330 late registration)

Accommodation

We have a block booking for accommodation at St. Anne's College for the 5 nights from Sunday 27 September to Friday 2 October. The price will be £450. 

International Advisory Committee

Sergey Alekhin (Hamburg), Johannes Blümlein (DESY), Stefan Dittmaier (Freiburg), Claude Duhr (Bonn), Keith Ellis (Durham), Thomas Gehrmann (Zürich), Nigel Glover (Durham), Joey Huston (Michigan State), Karl Jacobs (Freiburg), Judith Katzy (DESY), Frank Krauss (Durham), Jean-Philippe Lansberg (Orsay), Fabio Maltoni (Louvain), Michelangelo Mangano (CERN), Zoltan Nagy (DESY), Eram Syed Rizvi (QMUL), Frank Siegert (Dresden), Dominik Stöckinger (Dresden), Robert Szafron (BNL), Zoltan Trocsanyi (Budapest), Doreen Wackeroth (Buffalo), Ciaran Williams (Buffalo).

Local Organising Committee

Co-chairs: Fabrizio Caola (Oxford), Claire Gwenlan (Oxford), Chris Hays (Oxford), Gavin Salam (Oxford)

Members: Sneha Malde (Oxford), Martin Völkl (University of Birmingham), Nick Wardle (Imperial College London)

Monday 28 September

1 Registration

Plenary

Convener: Laura Reina

2 Welcome

Speakers: Chris Hays (University of Oxford (GB)), Claire Gwenlan (University of Oxford (GB)), Fabrizio Arturo Caola (University of Oxford (GB)), Gavin Salam (University of Oxford)

QCD@LHCintro.pdf

3 Highlights from CMS

Speaker: Robert Schoefbeck (Austrian Academy of Sciences (AT))

26-09-28 QCD at LHC - CMS Highlights.pdf

26-09-28 QCD at LHC - CMS Highlights.pptx

4 Highlights from ATLAS

Speaker: Nuno Castro (LIP and University of Minho)

ATLAS-Highlights-NunoCastro-QCDatLHC2026-Oxford.pdf

5 Recent developments in PDFs

Speaker: Stefano Forte (Università degli Studi e INFN Milano (IT))

oxpdf26.pdf

10:40 Tea and coffee

Plenary

Convener: Klaus Rabbertz (KIT - Karlsruhe Institute of Technology (DE))

6 PDFs: an experimental perspective

Speaker: Amanda Sarkar (University of Oxford (GB))

QCD@LHC2026.pdf

7 Low-scale QCD in simulations

Speaker: Steffen Schumann

QCDatLHC26_Schumann.pdf

8 QCD measurements at low scales

Speaker: Weijie Jin (University of Zurich (CH))

QCD@LHC.pdf

9 Lunch directions

StAnnes-lunch-Monday-Thursday.pdf

13:00 Lunch

Lunch will take place across two locations: the Dining Hall ("E" on the linked map) and Foyer B (in the Ruth Deech Building, "F") https://www.st-annes.ox.ac.uk/current-students/map/

Higgs, EW, and BSM

Conveners: Dr Alexander Karlberg (CERN), Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Daniel Winterbottom (Imperial College (GB)), Mika Anton Vesterinen (University of Warwick (GB))

10 Higgs boson production and decay rate measurements with the ATLAS experiment

With the full Run 2 pp collision dataset collected at 13 TeV, very precise measurements of Higgs boson production and decay rates can be performed, shedding light over the electroweak symmetry breaking mechanism. This talk presents these precise measurements including total and fiducial cross-sections for the main Higgs boson processes as well as branching ratios into final states with bosons and fermions. Differential cross-sections in a variety of observables are also reported, as well as a fine-grained description of the Higgs boson production kinematics within the Simplified Template Cross-section (STXS) framework.

Speaker: Bai-Hong Zhou (Tsung-Dao Lee Institute (CN))

Higgs_measurement_baihong-v2.pdf

11 Higgs Cross section measurements at CMS, bosonic channels

We will discuss the latest differential measurements of Higgs boson cross sections with the CMS detector in bosonic decay channels. Both fiducial differential cross section measurements and measurements in the simplified template cross section framework will be presented. The data collected during Run 3 of the LHC by the CMS experiment are used.

Speaker: Nico Härringer (ETH Zurich (CH))

HiggsXSBosonic.pdf

12 Higgs properties (mass, width, CP) measurements from ATLAS

This talk presents precise measurement of the properties of the Higgs boson, including its mass, total width, spin and CP quantum number. The measurements are performed in various Higgs boson production and decay modes, as well as their combinations.

Speaker: Runxuan (Max) Wang (University of Michigan (US))

Higgs_Width_and_CP_measurements_Max.pdf

13 Higgs property measurement

Covering Higgs property measurements of mass, width, CP and anomalous couplings and EFT

Speaker: Leyun Gao (Peking University (CN))

report.pdf

14 Higgs Combinations & EFT interpretations

Combination of measurements from different Higgs boson productions and decays will maximize the statistical power, and also allow decoupling the production from decay. This talk presents the latest combined measurements of the Higgs boson production cross-sections and decay branching ratios by the ATLAS experiment based on LHC Run 2 data, including Simplified Template Cross Sections (STXS) results and coupling modifier (kappa) tests. The combined measurements are interpreted using the effective field theory framework to probe new physics. Interpretation in the context of Effective Field Theory (EFT) frameworks are also shown.

Speaker: Matthew Kenneth Maroun (University of Massachusetts (US))

higgscombinations_Maroun_qcdlhc2026.pdf

Low-scale QCD, including heavy-ion physics

15 Soft QCD measurements with pp collisions in ATLAS

Measurement of soft QCD and DPI-related processes offer insights to understand QCD phenomena at small energy scales and non-perturbative regime, probe mechanisms for multi-parton interactions, and search for undiscovered phenomena such as QCD instantons. This talk presents the relevant results in this sector from the ATLAS experiments

Speaker: José Pretel (University of Victoria (CA))

qcd_at_lhc_2026_jpretel_dps.pdf

16 Minibias measurements with pO collisions in ATLAS

The utilisation of pO collision events at the LHC offers complementary means to test QCD predictions, and in particular provides sensitive probes to hadronic models that connect with cosmic-ray physics. This talk presents the minibias measurements with pO collusions from the ATLAS experiment.

Speaker: Lydia Audrey Beresford (Deutsches Elektronen-Synchrotron (DE))

LB_QCD_at_LHC.pdf

17 Jet production in photon-lead collisions at NLO+PS accuracy

Ultraperipheral Pb+Pb collisions at the LHC produce quasi-real photons reaching high energies, making photonuclear jet production a probe of the partonic structure of both the nucleus and the photon. We present NLO+PS predictions for photonuclear jet production matched to the observables of the ATLAS UPC Pb+Pb measurement at sqrt(s_NN) = 5.02 TeV. This provides the parton-shower-matched calculation identified as necessary for incorporating this data into global PDF fits. We quantify and compare scale, photon-PDF, and nuclear-PDF uncertainties across the measured phase space. These results are directly relevant to upcoming global fits of both nuclear and photon PDFs, with implications extending to the Electron-Ion Collider programme.

Speaker: Peter Meinzinger (Zürich University)

Meinzinger-QCDatLHC-PNJ.pdf

18 Using low-pt dimuon events to measure transverse proton structure

We present new methods for measuring the transverse structure of the proton, relying on ratios of event activity variables between events with a low-pt pair of muons and minimum bias events. The event activity is used in a similar way to centrality in heavy ion physics, and the evolution of the hard-process cross section provides information on the effective partonic luminosity as a function of the impact parameter between the protons. We show how the measured effective luminosity can be used to calculate the expected Double Parton Scattering (DPS) cross section within the pocket formula framework. The dependence of the transverse proton structure and the DPS cross section on partonic-x can be measured with this method. Observation of this dependence is expected to be achievable with currently collected data by the LHC experiments based on estimates of the effect size in pythia models.

Speaker: Kyle Cormier (University of Zurich (CH))

ProtonStructureAtTheLHC-1.pdf

19 Beam-spin induced polarization of lambda and anti-lambda hyperons in semi-inclusive deep-inelastic scattering (REMOTE)

The beam-spin induced polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons produced in deep-inelastic scattering of longitudinally polarized positrons from unpolarized nucleons has been investigated by the HERMES experiment at a positron beam energy of 27.6 GeV impinging on hydrogen, deuterium, and various heavier gas targets. The two spin-transfer coefficients $D_{LX}$ and $D_{LZ}$ are extracted and are found to be small and mostly compatible with zero within their statistical and systematic uncertainties, essentially independent of the relevant kinematic variables. The results constrain novel spin-dependent fragmentation functions, among others the helicity fragmentation function describing the hadronization of longitudinally polarized quarks into longitudinally polarized hadrons.

Speakers: Denis Veretennikov (AANL - Alikhanyan National Science Laboratory), Denis Veretennikov

PDFs and DIS

Convener: Gitanjali Poddar (University of London (GB))

20 Towards the NNPDF4.1 global PDF analysis

We present NNPDF4.1, a new release of the NNPDF family that consolidates and extends theoretical, methodological, and experimental progress achieved since NNPDF4.0. On the theory side, predictions for hadron collider observables are now based on state-of-the-art NNLO calculations interfaced to fast interpolation grids, and the analysis systematically incorporates missing higher order uncertainties (MHOUs), approximate N3LO corrections, and QED effects with the photon PDF. On the methodology side, NNPDF4.1 is based on an ensemble of ML models rather than a single one, following a new GPU-accelerated approach to hyperparameter optimisation, and benefit from improved positivity constraints, more general flavour assumptions, and an extended closure and future test validation. The input dataset is enlarged by more than 1200 new data points from 27 new datasets, including several Run II legacy measurements entering a PDF determination for the first time, selected through a systematic dataset selection procedure. We compare NNPDF4.1 to previous NNPDF determinations and to other recent PDF fits, and present a first study of its phenomenological implications.

Speaker: Kamil Laurent (Nikhef)

NNPDF_Oxford - 28-09-2026.pdf

21 MSHT: Updates

We provide an update of the MSHT parton distribution functions. We concentrate on the impact of both new data sets and an improved theoretical and statistical analysis for PDFs at high x values, including an investigation. of higher twist contributions. We also consider the potential impact of Electron Ion Collider DIS data on PDFs, and in particular on the extraction of the strong coupling constant. Finally, we present an update of the MSHT20 approximate N3LO PDFs

Speaker: Dr Lucian Alexander Harland-Lang (University College London)

lhl_QCD@LHC26_msht_compressed.pdf

22 New Directions in Precision PDF Analysis

We present recent developments in the global analysis of the proton, including those within the CT25 family of precision parton distribution functions (PDFs) and related theoretical and methodological advances. Beyond the phenomenological implications of CT25 for collider predictions at the LHC and elsewhere, we also discuss novel approaches to nonperturbative parametrization and the growing role of AI/ML techniques in the hadron structure inferencing problem. Together, these efforts point toward a more flexible and expressive framework for extracting PDFs from an increasingly diverse body of high-energy data.

Speaker: Timothy Hobbs (Argonne National Laboratory)

Hobbs_QCDLHC_26.pdf

23 Prospects for proton structure functions, PDFs, and strong coupling determinations at the EIC

Of the many measurements that will be possible at the Electron-Ion Collider (EIC), inclusive Deep Inelastic Scattering (DIS) measurements offer excellent opportunities to advance our understanding of the collinear structure of the proton, and QCD. We explore the potential for extracting proton structure functions, proton parton density functions (PDFs), and the strong coupling $\alpha_s(M_Z^2)$, using simulated EIC data, both standalone, and in combination with HERA data. Different beam energy and luminosity scenarios are considered, and the Rosenbluth separation method is used to determine the precision with which the proton structure functions $F_2$ and $F_L$ may be extracted at the EIC, in a model-independent manner. Additionally, the impact of EIC electron-proton DIS data on the precision of the proton PDFs is evaluated through the inclusion of simulated data in a global QCD fit at NNLO, performed in the HERAPDF2.0 framework. The simultaneous fitting of the PDFs and $\alpha_s(M_Z^2)$ indicates that the strong coupling may be determined to potentially world leading precision with inclusive DIS data alone, even during the early years of EIC operation.

Speaker: Stephen Maple

SMaple_QCD@LHC.pdf

15:40 Tea and coffee

Heavy Quarks

24 Hadronization studies at LHCb

The forward coverage of the LHCb detector (2 < η < 5) provides an interesting setting to study hadronization in jets. LHCb is particularly well-suited for studying hadronization in events initiated by light-quarks and heavy-quarks, given the enhancement of the relevant cross sections at forward rapidities and the capability of cleanly tagging these events.
Heavy-flavour-tagged events are of special interest, as heavy quarks exhibit distinct perturbative radiation patterns and nonperturbative hadronization dynamics compared to light quarks and gluons. In this talk, we will briefly review the experimental conditions at LHCb to provide context for the measurements, and then delve deeply into the latest results of hadronization studies at LHCb.

Speaker: Esteban Felipe Molina Cardenas (University of Michigan (US))

QCD@LHC2026-v3.pdf

25 Heavy-flavour jet measurements with ALICE

Measurements of heavy-flavour jets in pp collisions provide important tests of Quantum Chromodynamics (QCD) calculations. Jet substructure observables offer insight into the parton-shower evolution and the different radiation patterns of quarks and gluons arising from the different Casimir colour factors and parton masses. Comparisons between jets containing heavy-flavour baryons or heavy-flavour mesons probe heavy-quark hadronisation mechanisms and test the assumption of universality of charm-quark hadronisation across different collision systems.

In this contribution, a collection of recent ALICE measurements about heavy-flavour jets in pp collisions is presented. First, a set of observables involving charm jets identified by reconstructing $\mathrm{D^{0}}$ mesons is shown. We discuss measurements related to different choices of jet-axis definition, complemented by the generalised jet-angularity measurements for $\mathrm{D^{0}}$-tagged jets. These two measurements provide systematic insight into the radiation pattern and fragmentation of charm quarks during the parton-shower evolution. Then, we present the first measurement of the energy-energy correlator in $\mathrm{D^{0}}$-tagged jets, which resolves the angular structure of the energy flow of QCD radiation and allows for the separation of perturbative and non-perturbative regimes. Extending these studies in the charm-baryon sector, we compare the results of $\mathrm{D}$-meson jets with those of $\mathrm{\Lambda^{+}_{c}}$-tagged jets, thereby providing insight into charm-quark hadronisation mechanisms. Finally, we present the new b-jet production cross section measured with a b-jet tagging algorithm based on a graph neural network. These results provide new benchmarks for perturbative QCD calculations and establish a baseline for future b-quark energy loss studies in heavy-ion collisions.

Speaker: Yoshini Bailung (Institut de Physique des 2 Infinis (IP2I) de Lyon, CNRS-IN2P3, Université de Lyon)

QCD@LHC26-Yoshini_vF.pdf

26 Substructure of Heavy Quark Jets

We will present new results for the jet substructure of heavy quark initiated jets, focussing on jet angularities measured on jets initiated by a b-quark and discuss phenomenological results from arXiv:2606.20798.

Speaker: Andrea Ghira (Università degli studi di Genova)

Ghira_QCD@LHC26.pdf

27 Flavor Anomalies and Lepton Flavor Universality at CMS

Over the past decade, several measurements in the flavor sector performed at dedicated beauty experiments, such as BELLE, BaBar and LHCb, have shown a significant tension with respect to SM predictions. The flavor puzzle of the SM remains one of the open questions in high energy particle physics up until today and needs further investigation. This talk summarizes flavor measurements performed at the CMS detector over the last years, underlining its B physics potential and contribution to the flavor sector.

Speaker: Patricia Helena Wagner (ETH Zurich (CH))

Flavor_Anomalies_and_Lepton_Flavor_Universality_at_CMS.pdf

28 Analytic Computation of the Two-Loop Penguin Jet Function

In this talk, I will present recent progress in the analytic computation of the two-loop penguin jet function. This function is a key ingredient in the factorised description of the $Q_1$-$Q_{7\gamma}$ interference contribution to inclusive (B)-meson decays, which constitutes an important source of theoretical uncertainty in precision flavour physics. Its analytic computation therefore represents an important step towards improving theoretical predictions for these observables.
This calculation requires the evaluation of a set of master integrals that depend on the charm-quark mass as well as the energy sharing between the quark and antiquark. I will demonstrate how all relevant master integrals can be computed analytically in terms of iterated integrals by separating the dependence on the different scales.

Speaker: Kevin Brune (JGU Mainz)

QCDLHC_Brune.pdf

High-scale QCD

Conveners: Federico Buccioni (CERN), Dr Federico Sforza (University and INFN Genoa), Jennifer Roloff (Brown University (US))

29 QCD jet measurements in ATLAS

Direct measurements of processes involving QCD jets provide a key probe of QCD interactions, and in which, the multi-jet and vector boson plus jets processes are key channels in this measurement program. This talk presents recent measurements in this sector from the ATLAS experiment.

Speaker: Hanfei Cui (University College London)

qcd_lhc_2026_atlas_jet.pdf

30 Accurate predictions for LHC Processes at the highest partonic energies

The predictions relevant for two recent measurements by ATLAS have highlighted the necessity of developing methods to systematically tackle the intricate behaviour of large logarithmic corrections in the perturbative series in order for predictions to be accurate and useful. Specifically, the analysis of the processes of the production of at least two jets ($pp\to jj$ [https://arxiv.org/abs/2405.20206]) and the production of a hard photon or an electroweak vector boson in association with at least two jets ($pp\to\{\gamma,Z,W}+jj$ [https://arxiv.org/abs/2403.02793]) all indicate systematic deviations from data with increasing partonic collision energy for e.g. fixed order perturbative predictions. Perturbative predictions taking into account the source of the large logarithmic corrections at high energies on the other hand obtain stable predictions of data [https://arxiv.org/abs/2403.02793, https://arxiv.org/abs/2506.17438].

While the high energy logarithmic corrections to the perturbative series have been studied for some time, this is the first conclusive demonstration of the need for their inclusion in standard analyses at the LHC. The predictions for photon+dijets taking into account the effects of high energy resummation was presented in https://arxiv.org/abs/2506.17438. In this talk we will present new results for the process Z+dijets, which confirm the dominance of the logarithmic terms in the NLO fixed-order results, and confirm the resolution of the logarithmic problem by an all-order resummation, which also compares favouably to experimental data. Finally, we discuss the merits of scale choices in fixed-order calculations of order the partonic collision energy.

Speaker: JEPPE ROSENKRANTZ ANDERSEN (IPPP, University of Durham)

Andersen_QCDLHC.pdf

31 Drell-Yan precision measurements in ATLAS

The precision measurements of Drell-Yan processes offer in-depth understanding of QCD interactions and important constraints on SM parameters and PDFs. This talk presents recent Drell-Yan precision results from the ATLAS experiment.

Speaker: James Ferrando (Lancaster University (GB))

qcd-at-lhc-dy.pdf

32 Diphoton production at N3LO

The production of two isolated photons in high-energy hadron collisions poses a challenge to perturbative QCD because of large corrections through next-to-next-to-leading order (NNLO). We present novel next-to-next-to-next-to-leading order (N3LO) predictions and finally demonstrate perturbative convergence for this process. We discuss the considerable computational challenges and phenomenological results for the Large Hadron Collider.

Speaker: Rene Poncelet (IFJ PAN Krakow)

2026.09.28-Oxford-QCD@LHC-poncelet.pdf

33 Photon-induced QCD@FCC-ee

Lepton colliders produce large fluxes of quasi-real photons via the equivalent photon approximation. We present a study for the proposed FCC-ee, showing these fluxes enable a broad photon-QCD program.
While photon-induced dijet production gives access, for example, to $\alpha_S$ determinations, jet substructure, etc., the talk centers on deep-inelastic scattering of leptons on collinear photons. We determine the $(x,Q^2)$ coverage attainable at FCC-ee, after subtraction of the $ee \to WW$ background, and the role of forward lepton detectors.

Speaker: Peter Meinzinger (Zürich University)

Meinzinger-QCDatLHC-photonDIS.pdf

New techniques, tools and generators

34 "Hadron-in-fat-jet'' AI Tagging to Detect Rare Decays

We investigate a novel class of boosted-object signatures at the LHC, where a high-pT fat-jet contains an identifiable hadron or quarkonium state originating from rare or semi-exclusive decays. Unlike conventional boosted jet studies, which focus on multi-prong partonic substructure, our approach probes hybrid configurations such as W±→π±γ, where a localized hadronic or quarkonium signal is embedded within a collimated jet. By fine-tuning the signature-oriented, pre-trained Sophon AI model optimized for large-radius jets, and combining it with an event-level BDT and a soft-drop-mass shape fit, we obtain an expected 95\% CL upper limit of (W±→π±γ)<2.78×10−5 for 450fb−1 in our nominal setup. This study serves as a first proof-of-principle demonstration of the ``hadron-in-fat-jet'' paradigm; substantial gains in sensitivity are expected from improved trigger strategies, additional production channels, and dedicated taggers, while the methodology itself is broadly applicable to a wide range of rare Standard Model processes and searches for light or exotic resonances at present and future collider experiments. https://arxiv.org/abs/2606.09458

Speakers: Mr Linrui Chen (Peking University), Qiang Li (Peking University (CN)), Youpeng Wu (Peking University (CN))

WtoPia_QCDatLHC2026.pdf

35 (YSF) Advances in Hadronic Tau Reconstruction and Identification in ATLAS Using Graph Neural Networks

Hadronically decaying tau leptons are essential signatures in many ATLAS measurements and searches, including studies of the Higgs boson and potential new physics. Their identification is particularly challenging due to the large background from quark and gluon initiated jets in proton-proton collisions. This poster presents an overview of hadronic tau reconstruction and identification in the ATLAS experiment, with a focus on the newly developed GNTau algorithm, a transformer-based neural network that combines information from charged-particle tracks, calorimeter energy deposits, and high-level observables. Public Run-3 performance studies demonstrate that GNTau significantly improves the rejection of misidentified jets compared to the previous recurrent neural network (RNN) based approach while maintaining the same signal efficiency across a wide range of transverse momentum, pseudorapidity, and pileup conditions. These advances enhance the sensitivity of ATLAS analyses involving tau leptons and represent an important step toward precision measurements and future discoveries at the High-Luminosity LHC.

Speaker: Pim Bijl (University of Freiburg (DE))

Tau_ID_28_9_2026.pdf

36 Scaling Neural Simulation Based Inference to Large Datasets

Neural simulation-based inference (NSBI) in HEP predominantly relies on event-level likelihood or likelihood-ratio estimators. In non-trivial settings, these require expensive post-hoc profiling or marginalization over nuisance parameters to perform dataset-wide inference. We introduce PAIRS, a two-stage procedure that learns an event representation from small datasets ($N \le 2$). Under mild regularity assumptions, this results in an observable that is information-preserving and has a simple, fast composition rule, with the potential to resolve a fundamental scaling bottleneck for NSBI at the LHC. Validated on several benchmarks, including a resonance search inspired by LHC bump hunts, PAIRS empirically matches or outperforms dataset-wide training at a fraction of the compute for a variety of problems and offers a practical path to enable amortized inference over large datasets.

Speaker: Chris Pollard (University of Warwick (GB))

POLLARD-QCDLHC20260928.pdf

37 DIS-secting the universe with high-energy neutrinos

We revisit the impact of electroweak (EW) radiative corrections on the kinematic distributions of charged leptons in neutrino-induced Charged-Current (CC) Deep Inelastic Scattering (DIS). We implement full Next-to-Leading Order (NLO) EW corrections to CC DIS in a flexible Monte Carlo framework, supplemented with higher-order logarithmically enhanced final-state QED radiation. We compare our results to exclusive NLO QCD plus Parton Shower (PS) predictions obtained with an existing POWHEG-BOX-RES event generator, examining different PS models and settings. Based on this comparison, we provide recommendations for the use of the POWHEG-BOX event generator in experimental analyses. We further assess the impact of radiative corrections on the correlation between the observed muon energy and the incoming neutrino energy for a realistic astrophysical neutrino flux.
These corrections can exceed 10%, yet they are reliably described across several orders of magnitude in energy.

Speaker: Lorenzo Guerra (Max Planck Institute for Physics)

QCD@LHC_2026_Guerra.pdf

18:00 Reception

Tuesday 29 September

Plenary

Convener: Guilherme Milhano (LIP-Lisbon & CERN TH)

38 QCD measurements at high scales

Speaker: Matt LeBlanc (Brown University (US))

2026_MLB_QCDatLHC.pdf

39 Recent developments in QCD predictions for collider physics

Speaker: Chiara Signorile-Signorile (CERN)

qcd@lhc_signorile.pdf

40 EEC, Track functions and related topics

Speaker: Wouter Waalewijn (University of Amsterdam)

EEC_QCD_at_LHC2026.pdf

10:30 Tea and coffee

Plenary

Convener: Amanda Cooper-Sarkar (University of Oxford (GB))

41 Recent lattice developments and results

Speakers: Marina Krstic Marinkovic (ETH Zurich), Marina Krstic Marinkovic (ETH Zurich)

Marinkovic_QCDatLHC_092926_v2.pdf

42 Panel discussion on alpha_s

Speakers: Alberto Ramos Martinez (Univ. of Valencia and CSIC (ES)), David d'Enterria (CERN), Giulia Zanderighi (Max Planck Institut für Physik)

alphas_roundtable_qcd_at_lhc_oct2026.pdf

12:30 Lunch

Heavy Quarks

43 ATLAS results on top properties and threshold region

In this contribution, the top quark mass measurements by the ATLAS experiment are reviewed. In addition, new ATLAS results on top-quark properties are shown. Finally, results of the measurements around the top pair production threshold are summarised.

Speaker: Lucas Cremer (Technische Universitaet Dortmund (DE))

QCD@LHC_2026.pdf

44 Top quark pair in the threshold at the LHC: NRQCD and key-uncertainties

We present predictions for top quark pair production at the LHC in the threshold region, including quasi-bound-state effects associated with Coulomb interactions within the framework of NRQCD. We focus on the invariant mass distribution of the produced top quark pair, incorporating NLL soft-gluon threshold resummation.
A detailed study of the theoretical uncertainties affecting these predictions is presented. We consider variations in the top quark mass and width, the strong coupling $\alpha_s$, renormalization and factorization scales, and parton distribution functions, as well as uncertainties associated with the color-singlet and color-octet Green’s functions describing quasi-bound state formation. These uncertainties are compared with those from standard fixed-order QCD predictions, and implications for analyses by ATLAS and CMS are discussed.

Speaker: Giovanni Limatola (II. Institute for Theoretical Physics University of Hamburg)

limatola_QCD@LHC.pdf

45 ATLAS results on top quark cross section measurements and recent progress on modelling

The exceptionally large dataset collected by the ATLAS detector at the highest proton-proton collision energies provided by the LHC enables precision testing of theoretical predictions using an extensive sample of top quark events. Measurements of the inclusive top quark production rates at the LHC have reached a precision of several percent and test advanced Next-to-Next-to-Leading Order predictions in QCD. Differential measurements in several observables are important to test SM predictions and improve Monte Carlo generator predictions. In this contribution. several cross-section measurements will be presented as well as the studies on the state-of-the art Monte Carlo generators.

Speakers: Daniel Ernani Martins Neto, Daniel Ernani Martins Neto (Polish Academy of Sciences (PL))

ttbar_results_QCD@LHC2026_DANIEL_ERNANI_vfinal.pdf

46 Complete NLO corrections to off-shell $t \bar{t}$ production in the $\ell+j$ decay channel

We present the calculation of the complete NLO corrections to the off-shell top-quark pair production in the $\ell+j$ decay channel, denoted as $pp \to \ell^- \bar{\nu}_{\ell}\, j_b j_b \,jj + X$, where $\ell^- = e^-,\, \mu^-$. The calculation consistently preserves the finite-width effects of the top quarks and massive gauge bosons, as well as takes into account all doubly-, singly-, and non-resonant contributions along with their interference effects. All Born-level contributions, at the perturbative orders from ${\cal O}(\alpha_s^4\alpha^2)$ to ${\cal O}(\alpha_s^0\alpha^6)$, are included and corrected by both NLO QCD and NLO EW effects. Furthermore, all possible partonic initial states are taken into account. Particular attention is paid to the infrared safety in the presence of photons and jets. This requires the use of the so-called parton-to-photon fragmentation function and the photon-to-jet conversion function, which makes the democratic photon–parton clustering and the $\gamma \to q\bar{q}$ splittings finite. We present our findings at the integrated and differential fiducial cross-section levels for the LHC Run III centre-of-mass energy of $\sqrt{s}= 13.6$ TeV. In addition, we quantify the impact of subleading NLO effects, in particular, electroweak Sudakov logarithms and non-resonant QCD backgrounds. Two analysis strategies are employed and compared, namely with and without the resonance-enhancing requirement on the invariant mass of the two light jets, $|M_{jj}-m_W|<{\cal Q}_{\text{cut}} = 20$ GeV, illustrating the relationship between QCD background suppression, off-shell effects, interferences, and complete NLO corrections.

Speaker: Leon Mans (RWTH Aachen University)

QCD_LHC_2026_Mans.pdf

47 Top Quark Pair Production and Decay: The 1-Higgs-Singlet Model and Pseudoscalar Decay

The process of top quark pair production through the decay of the scalars in the 1 Higgs Singlet extension of the Standard Model is associated with large interference effects between the loop-induced 'SM-like' Higgs and the heavy Higgs amplitudes, and the QCD continuum background. We attach leptonic decays to the di-top final state at NLO and study the effects of spin correlation in the process. We also make phenomenological predictions for the leptonic decays of the top quark pair produced by the decaying of a CP-odd pseudoscalar at the LHC at NLO accuracy, with the full spin correlation effects preserved in the decayed products. We attach Parton Showers and perform analyses of differential cross sections as functions of various parameters to study the significance of the results in searches for new scalars and pseudoscalars beyond the Standard Model.

Speaker: Vishakha Lingadahally

QCD@LHC_Top-Quark-Pair_Decay_2HDM_Lingadahally.pdf

Higgs, EW, and BSM

Conveners: Dr Alexander Karlberg (CERN), Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Daniel Winterbottom (Imperial College (GB)), Mika Anton Vesterinen (University of Warwick (GB))

48 Higgs-Pair Production via Gluon Fusion: Top-Yukawa- and light-quark-induced electroweak Corrections

Gluon fusion, gg → HH, is the dominant Higgs-pair production process at the Large Hadron Collider (LHC) and provides the first direct access to the trilinear Higgs self-coupling. The process is loop-induced, with the leading contribution arising from top-quark loops within the Standard Model. QCD corrections for this process have been calculated up to NNLO and are known to substantially enhance the cross section. With the anticipated accuracies achievable at the high-luminosity LHC (HL–LHC), the theoretical uncertainties will be of increased relevance to compete with the experimental precision at the level of less than 30%. In this work, we take the next steps towards the complete NLO EW corrections by calculating the full top-Yukawa and light-quark induced contributions. These corrections are found to modify the cross section moderately in the kinematic regimes of interest. I will present the results of these calculations, discuss their impact on the total and differential cross sections, and outline the status of the remaining contributions required to build the complete NLO EW result.

Speaker: Jamie Chang (ETH Zurich / PSI)

QCDatLHC.pdf

QCDatLHC.pptx

49 Recent analytic progress for di-Higgs production

Di-Higgs production is the most promising experimental signature to measure the cubic Higgs self-interaction at the LHC and its high luminosity upgrade. In this talk I will report on recent progress on analytic results for the computation of di-Higgs production in controlled expansions, which cover the whole physical phase space. This encompasses recent results on NNLO virtual corrections, which are needed to reduce the top mass scheme dependence at NLO, as well as NLO EW corrections. I will also cover the implementation of these and related results into the publicly available package ggxy.

Speaker: Kay Schoenwald (CERN)

qcd2026.pdf

50 CMS search for non-resonant HH

Covering SM searches for non-resonant HH and HHH productions

Speaker: Benjamin Lawrence-Sanderson (Northwestern University (US))

QCDatLHC_HHnonresCMS_BenjaminLawrence-Sanderson_v2.pdf

51 HH, HHH searches, Higgs potential at the LHC

In the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. Experimentally, the Higgs boson self-coupling and thereby the shape of the Higgs potential, can be probed through the production of Higgs boson pairs (HH). In this talk, the latest HH searches by the ATLAS experiment using the LHC Run 2 and Run 3 datasets are reported. Non-resonant HH search results are interpreted both in terms of sensitivity to the Standard Model and as limits on the Higgs boson self-coupling and the quartic VVHH coupling.

Speaker: Mirella Dimitrova Vassilev (SLAC National Accelerator Laboratory (US))

QCDLHC_MV.pdf

52 N3LO QCD predictions for boosted Higgs-strahlung off a W boson at the LHC

We consider the production of a boosted Higgs boson in association with a charged weak ($W$) boson from proton-proton collisions at the LHC. Using the $q_T$-slicing formalism, we obtain the first fully differential predictions for this process at next-to-next-to-next-to-leading order (N$^3$LO) in perturbative QCD.
In the boosted regime, the N$^3$LO corrections are about $+2\%$, and remain outside the scale envelope of the previous order. At the same time, the dependence of the N$^3$LO prediction on perturbative scales is reduced to below the percent level.
This result marks an important milestone towards meeting the Higgs precision goals for the LHC and its High-Luminosity phase.

Speaker: Federico Silvetti (IPPP)

QCD_LHC2026_Silvetti.pdf

PDFs and DIS

Convener: Gitanjali Poddar (University of London (GB))

53 Proton structure at the LHC with neural simulation-based inference

The precise determination of the parton distribution functions (PDFs) of the proton is an essential ingredient for LHC analyses, including the upcoming High-Luminosity upgrade. PDFs are determined from a global scattering of hard scattering data taking as input unfolded low-dimensional binned cross- sections. In this work we demonstrate the feasibility of deploying neural simulation-based inference (NSBI) to constrain the proton PDFs from unbinned, high-dimensional, detector level observables taking into account all relevant experimental and theoretical systematic uncertainties. We develop procedures that allows for a detailed account of systematic uncertainties in the unbinned modeling of the high-dimensional data set and how that interplays with the PDF extraction. Adopting as proof-of-concept the determination of the large-x gluon PDFs from top quark pair production, preliminary results with our pipeline demonstrate significant sensitivity improvements as compared for traditional low-dimensional binned analyses.

Speaker: Robert Schoefbeck (Austrian Academy of Sciences (AT))

26-09-29 PDF NSBI QCDatLHC.pdf

26-09-29 PDF NSBI QCDatLHC.pptx

54 Drell-Yan measurements with CMS for PDF determinations

Differential measurements of the Drell-Yan cross section play a central role in constraining the proton parton distribution functions (PDFs) while simultaneously enabling precision tests of perturbative QCD. Measurements spanning inclusive Drell-Yan production and final states in association with jets explore complementary regions of the parton momentum fractions and momentum-transfer scales.

In particular, Z+jet production allows the boost and scattering dynamics of the hard interaction to be disentangled. The average rapidity of the Z boson and the jet is sensitive to the longitudinal boost of the underlying partonic system, while their rapidity difference characterizes the scattering kinematics in the partonic center-of-mass frame. Combined with the transverse momentum of the Z boson, these observables offer increased sensitivity to the proton PDFs.

Comparisons with state-of-the-art NNLO QCD predictions, supplemented by NLO electroweak and nonperturbative corrections, demonstrate the sensitivity of these measurements to the proton PDFs and their potential impact on future global PDF determinations.

Speaker: Cedric Verstege (KIT - Karlsruhe Institute of Technology (DE))

DY for PDFs (QCD@LHC 26).pdf

55 Simultaneous PDF fits and parameter extractions (including weak mixing angle and alpha_s) at CMS

Simultaneous PDF fits and parameter extractions (including weak mixing angle and alpha_s) at CMS

Speaker: Klaus Rabbertz (KIT - Karlsruhe Institute of Technology (DE))

Fitting-PDFs-as-sin2tw_CMS_QCDatLHC_20260929.pdf

56 ATLAS measurements of alphaS

This talk will cover recent ATLAS determinations of the strong coupling constant, $\alpha_s$, highlighting the increasingly important role of parton distribution functions in precision measurements.

Speaker: Laura Fabbri (Universita e INFN, Bologna (IT))

AlphaS_QCDatLHC2026.pdf

57 Electroweak measurements at LHCb and their interplay with proton PDFs

The forward acceptance of the LHCb detector provides unique sensitivity to parton distribution functions in kinematic regions complementary to those probed by other LHC experiments. This talk reviews electroweak measurements at LHCb and their role in constraining proton structure. Particular attention is given to the interplay between PDF uncertainties and precision electroweak observables: quantities such as the W boson mass and the effective leptonic weak mixing angle are increasingly limited by knowledge of the proton's partonic content, while LHCb production measurements offer constraining power on the same distributions. Recent results are presented alongside prospects for forthcoming measurements with Run 3 data, and the potential for dedicated forward measurements to reduce PDF uncertainties in future precision tests of the Standard Model is discussed.

Speaker: William Barter (University of Edinburgh)

qcdlhc_Barter.pdf

15:40 Tea and coffee

High-scale QCD

Conveners: Federico Buccioni (CERN), Dr Federico Sforza (University and INFN Genoa), Jennifer Roloff (Brown University (US))

58 New Opportunities for Precision Hadronic Measurements at the LHC with Energy Correlators

With exciting future collider programs, such as the FCCee, on the horizon, interpretation of precision measurements at these facilities requires us to have already constrained the Standard Model parameters to a high degree of precision. Collider measurements impacted by strong interactions such as the strong coupling constant and the top quark mass remain bottlenecks in this program. In this talk, we report on recent progress in overcoming these challenges using energy energy correlators (EECs).

In EECs measured on heavy unstable resonances such as the $Z$, $W$, $H$ and the top, the resonance mass $M$ introduces an additional scale, generating a sharp peak at angles $\sim M/p_T^{\rm jet}$. For heavy bosons exhibiting a two-body decay, such as the $Z$, this feature can be computed directly by boosting the EEC spectrum measured in $e^+e^- \rightarrow {\rm hadrons}$ at the $Z$ pole, where the peak arises from boosting the well-studied Sudakov factorization governing the back-to-back limit of the two-point correlator. Beyond just a theoretical excericse, this can be pushed even further to devise a new competitive collider measurement of the bottom quark mass by exploiting the dead-cone feature of inclusive bottom decays in boosted $Z$ jets, while at the same time laying the theoretical foundation for the top mass determination using EECs.

Speaker: Zhen Xu (DESY)

QCD@LHC_2026_ZhenXu.pdf

59 Accounting for the Effect of Fiducial Cuts on Energy-Energy Correlators

We study the impact of fiducial acceptance cuts on Energy-Energy Correlators (EECs) in $e^+e^-$ annihilation into hadrons. Experimental measurements of EECs typically impose an angular acceptance defined with respect to oriented event-shape axes, such as thrust or sphericity, and correct the resulting phase-space loss using Monte Carlo efficiency factors.
We instead adopt a fully analytic approach and compute the fiducial EEC to $O(\alpha_s)$ using thrust and sphericity axes. We find that the impact of finite angular acceptance on measured EECs can reach up to 3$\%$ for both axes and induce nontrivial shape distortions that are uncontrolled in MC. We further use symmetry arguments to decompose the all-order EEC in terms of scalar structure functions, and propose a data-driven defiducialization strategy (inspired by similar techniques at the Tevatron and the LHC) to rigorously reconstruct the full phase-space EEC directly from differential measurements, eliminating the need for MC efficiency corrections.

Speaker: Alessio Vorona (Nikhef/UvA)

talk.pdf

60 Recent Highlights from the Electron–Positron Alliance

Recent advances in data preservation and modern analysis techniques have enabled a new generation of precision measurements using archived electron-positron collision data collected at the Large Electron-Positron Collider (LEP). The Electron-Positron Alliance is developing a broad physics program that applies contemporary experimental and theoretical tools to these unique datasets, establishing them as a precision laboratory for studies of Quantum Chromodynamics and jet physics. In this talk, we present an overview of recent results based on archived ALEPH and DELPHI data, including measurements of event-shape observables, jet spectra and substructure, energy-energy correlators, identified-particle production, and other precision QCD observables. These measurements probe perturbative radiation, hadronization, and the transition from partons to hadrons in a clean experimental environment, while providing stringent tests of modern event generators and theoretical calculations. We also discuss ongoing efforts to preserve, modernize, and extend the scientific reach of legacy collider datasets using new analysis methodologies. Together, these results demonstrate the continuing scientific value of archived LEP data, providing precision benchmarks for present and future collider experiments and illustrating the broader potential of the “recycling frontier” in particle physics.

Speaker: Ms Yi Chen (Vanderbilt University (US))

20260929_EEAllianceRecentResults_YiChen_v23.pdf

61 Event isotropy in perturbative QCD

It has recently been proposed that collider events can be equipped with a metric, the Energy Mover's Distance (EMD), which allows one to rephrase multiple aspects of collider physics in a geometric language. Further, the EMD can be exploited to define new observables. In this context, event isotropy quantifies the resemblance of an event to a uniform energy distribution. We present the first theoretical study of event isotropy within the framework of perturbative QCD. In particular, we first obtain the isotropy distribution in e+e− collisions semi-analytically at O(αs) (leading-order) and numerically at O(αs^2) (next-to-leading order, NLO). Furthermore, we obtain all-order theoretical predictions by resumming the contributions of soft and collinear emissions, at next-to-leading logarithmic (NLL) accuracy. By matching resummed and fixed-order predictions we reach NLL+NLO accuracy.

Speaker: Matteo Cacciari (LPTHE Paris)

isotropy.pdf

Low-scale QCD, including heavy-ion physics

62 Measurement of the jet quenching effect with Z+jet events in PbPb and pp collisions at 5.36 TeV with Run 3 data

The production of jets in association with Z bosons offers a uniquely clean probe of the quark-gluon plasma (QGP), as the Z boson's decay products bypass strong medium interactions, preserving the initial hard-scattering kinematics. We present the latest measurement of Z+jet correlations in the dimuon channel using the new 5.36 TeV Run 3 data collected by the CMS experiment in 2023 and 2024. The study focuses on the momentum imbalance between the Z boson and the recoiling jet, providing a direct and sensitive look at medium-induced energy loss and the in-medium evolution of partons. The unfolded $x_{Zj}$ distribution, compared with state-of-the-art theoretical calculations, offers crucial tests of the microscopic structure of the QGP. By leveraging the high statistics and increased energy of Run 3, this measurement provides new experimental leverage to constrain theoretical models of parton energy loss and the transport properties of the QGP. Furthermore, the unprecedented statistical precision of the anticipated full Run 3 dataset will pave the way for detailed studies of jet substructure in this clean Z+jet channel.

Speaker: Raffaele Delli Gatti (Universita e INFN Trieste (IT))

DelliGatti_QCDatLHC_2026_v3.pdf

63 How to actually measure jet quenching in heavy-ion collisions

The scattering of a well-controlled probe particle is a time-honored method to explore the structure and dynamics of matter. In heavy-ion collisions, the interaction of jets with the Quark-Gluon Plasma (“jet quenching”) promises such a probe. However, well-controlled jet reconstruction in the complex environment of nuclear collisions is extraordinarily difficult – the thousands of particles generated in a head-on collision of lead ions at the LHC do not come labeled “jet” or “background.” The HEP jet toolkit for mitigating underlying event and pileup effects in p+p collisions is helpful for very energetic jets in this environment, where the signal/background is large. However, such jet-wise correction approaches fail badly for by far the largest part of jet production phase space, where jet quenching effects are expected to be sizable, and where we need to measure to track the dissolution of jets in the plasma. Machine Learning is useless in this region, because its training requires accurate background modeling (which is what the problem is). The solution, unsurprisingly, is to think about the problem statistically, carrying out data-driven background corrections at the level of ensemble-averaged distributions. This approach has been successfully applied in a wide variety of heavy-ion jet measurements at both the LHC and RHIC, enabling jet quenching measurements over the full jet production phase space at both colliders, and mapping experimentally how moderate-energy jets get blown apart by the QGP and how the QGP responds to that excitation. I will outline the statistical approach to heavy-ion jet measurements, and discuss notable recent results employing it from both the ALICE and STAR experiments.

Speaker: Peter Martin Jacobs (Lawrence Berkeley National Lab. (US))

Jacobs_QCDLHC26.pdf

Jacobs_QCDLHC26.pptx

64 Measurement of hyperon spin correlation in pp and pPb collisions at CMS

Spin correlations between hyperons provide a novel probe of spin-dependent particle production and hadronization in quantum chromodynamics (QCD). Using the high-statistics data collected by the CMS experiment, we present the first measurements of spin correlations for $\Lambda\Lambda$, $\Lambda\bar{\Lambda}$, and $\bar{\Lambda}\bar{\Lambda}$ pairs in pp collisions at $\sqrt{s}=13$ TeV and pPb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV. The correlations are measured as a function of the pair separation, $\Delta R=\sqrt{\Delta\eta^{2}+\Delta\phi^{2}}$. At small $\Delta R$, $\Lambda\Lambda$ and $\bar{\Lambda}\bar{\Lambda}$ pairs exhibit negative short-range spin correlations. No significant positive short-range spin correlation is observed for $\Lambda\bar{\Lambda}$ pairs, in qualitative contrast to previous observations at lower collision energies. These measurements provide new constraints on models of hyperon-pair production and on the origin of spin correlations in hadronic collisions.

Speaker: Jieke Wang (Shandong University (CN))

QCD@LHC-JiekeWang-v1.pdf

65 Collective flow measurements in OO and NeNe collisions with CMS

Measurements of collective flow in intermediate-size collision systems such as OO and NeNe are crucial for understanding the origin of collectivity in small systems and its evolution with collision system size. Using data collected by the CMS experiment at the LHC, flow coefficients of charged particles ($n=2,3$) are measured in OO and NeNe collisions using two- and multi-particle correlation techniques as functions of centrality. In addition, collective flow measurements of strange hadrons are presented to investigate the particle-species dependence. The results are compared with pp, pPb, and PbPb collisions, as well as with theoretical calculations, providing new insights into the origin of collectivity in small systems and information on the nuclear structure of oxygen and neon nuclei.

Speaker: Jiateng Peng (Fudan University)

QCD@LHC2026_Jiateng.pdf

New techniques, tools and generators

66 Status of the Alaric Parton Shower

In this talk I will present the status of the Alaric parton shower. I will discuss new results including matching to NLO, spin correlations and resonance and width aware matching strategies for $t\bar{t}$ production.

Speaker: Daniel Reichelt

QCDatLHC_2026_DReichelt.pdf

67 Double-real corrections to color singlet decay in a parton-shower inspired scheme

We introduce a local infrared subtraction method for next-to-next-to-leading order QCD calculations in color singlet decays, with counterterms based on scalar radiators and pure splitting functions. Overlapping singularities in the multipole radiation pattern are disentangled by partial fractioning, and the kinematics mapping corresponds to iterated next-to-leading order kinematics. We verify that the double-real remainder to $e^+ e^-\to q\bar{q}$ is rendered finite in the single and double unresolved limits and investigate the numerical convergence of the Monte-Carlo integral. We compute the phase-space integrals of the scalar counterterms in the back-to-back configuration, both analytically and with the help of numerical techniques based on sector decomposition.

Speaker: Max Knobbe (Fermilab)

knobbe_oxford.pdf

68 A first glimpse of matching beyond NLO with logarithmically accurate showers

The increasing precision at collider experiments calls for theoretical predictions that combine fixed-order accuracy with the fully exclusive description of final states provided by parton showers. Achieving this combination beyond next-to-leading-order remains a major challenge, in particular while preserving the logarithmic accuracy of the shower.
In this talk, we present first results towards higher-order matching using the PanScales framework. Focusing on $e^+e^-$ collisions, we construct a matching procedure that incorporates the full set of (double-)real leading colour $\mathcal{O}(\alpha_s^2)$ contributions, while retaining the logarithmic structure of the showers.
Beyond its immediate application to event-shape observables, our work establishes an important stepping stone towards higher-order matching in lepton collisions and provides a foundation for matching logarithmically accurate showers to higher-order calculations in hadron collisions.

Speaker: Nicolas Francois Schalch (University of Oxford (GB))

oxford-qcd-at-lhc-sep-2026.pdf

69 Resummed Distribution Functions: Making Perturbation Theory Normalized and Positive

Fixed-order perturbative calculations for differential cross sections can suffer from non-physical artifacts: they can be non-positive, non-normalizable, and non-finite, none of which occur in experimental measurements. We propose a framework, the Resummed Distribution Function (RDF), that, given a perturbative calculation for an observable to some finite order in αs, will ``resum'' the expression in a way that is guaranteed to match the original expression order-by-order and be positive, normalized, and finite. Moreover, our ansatz parameterizes all possible finite, positive, and normalized completions consistent with the original fixed-order expression, which can include NnLL resummed expressions. The RDF also enables a more direct notion of perturbative uncertainties, as we can directly vary higher-order parameters and treat them as nuisance parameters. We demonstrate the power of the RDF ansatz by matching to thrust to O(α3s) and extracting αs with perturbative uncertainties by fitting the RDF to ALEPH data

Speaker: Rikab Gambhir (University of Cincinnati)

[Oxford 2026] RDFs.pdf

70 Quarkonium parton shower in Herwig 7 (REMOTE)

I will present the implementation of a fully automated quarkonium parton shower in Herwig 7 based on non-relativistic QCD factorisation with explicit spin and colour projections. The framework incorporates both colour-singlet and colour-octet production channels, including gluon fragmentation and diquark production, and combines perturbative short-distance coefficients with non-perturbative NRQCD matrix elements to describe heavy-quark bound-state formation. Splitting functions for S-, P- and D-wave quarkonium states are derived and embedded in the angular-ordered shower evolution, with spin correlations, polarisation effects and feed-down contributions retained throughout. I will discuss the structure of the implementation and its phenomenological performance, including comparisons with LHC data.

Speaker: Aidin Masouminia (IPPP, Durham University)

OniumPS-Ox-AM.pdf

Wednesday 30 September

Plenary

Convener: Giulia Zanderighi (Max Planck Institut für Physik)

71 Generators and Tools in the experiments

Speaker: Dr Francesco Giuli (INFN e Universita Roma Tor Vergata (IT))

FGiuli_QCD@LHC26.pdf

72 Recent developments in shower matching

Speaker: James Whitehead (Jagiellonian University, Kraków)

Matching_JW.pdf

73 Recent spectroscopy measurements

Speaker: Jibo He (University of Chinese Academy of Sciences (CN))

20260930_Spectroscopy.pdf

10:30 Tea and coffee

Plenary

Convener: James Ferrando (Lancaster University (GB))

74 Results on CP Violation and B anomalies

Speaker: Christoph Michael Langenbruch (Heidelberg University (DE))

qcdatlhc_langenbruch.pdf

75 Heavy-flavour/Top precision predictions at colliders

Speaker: Simon Badger (University of Turin)

SB_QCDatLHC_2026.pdf

76 Top measurements at the LHC

Speaker: Andreas Werner Jung (Purdue University (US))

QCDatLHC2026_ajung.pdf

77 Introducing QCD@LHC27

Speakers: Rene Poncelet (IFJ PAN Krakow), Rene Poncelet (IFJ PAN Krakow)

QCD@LHC27.pdf

13:00 Lunch

78 OPMD Lab Tours

1/2-hour blocks, sign up at registration

PP_OPMD_DB.pdf

PP_OPMD_DB.pptx

Thursday 1 October

Higgs, EW, and BSM

Conveners: Dr Alexander Karlberg (CERN), Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Daniel Winterbottom (Imperial College (GB)), Mika Anton Vesterinen (University of Warwick (GB))

79 Multiboson measurements in ATLAS

The measurement of multiboson processes including diboson and triboson offers a stringent test of the SM electroweak structure, and provides complementary ways to constrain the high precision QCD and electroweak calculations. This talk presents recent results in this sector from the ATLAS experiment.

Speaker: Zihan Zhao (University of Science and Technology of China (CN))

Multiboson_ZihanZhao_v2.pdf

80 Multiboson Measurements at CMS

Measurements of processes involving multiboson final states constitute a precision test of the Standard Model. Moreover, discrepancies between theoretical predictions and experimental measurements could hint to new physics through the presence of anomalous gauge couplings. These processes are also dominant backgrounds for Higgs boson measurements, and searches for new particles with diboson final states. The most relevant and recent CMS measurements at 13 and 13.6 TeV will be presented.

Speaker: Cristiano Tarricone (Torino University and INFN (IT))

QCD@LHC2026_MultibosonProduction_CMS-8.pdf

81 Vector boson fusion and scattering measurements in ATLAS

The vector boson fusion and scattering processes offer an important avenue to test the Standard Model electroweak theory, the electroweak symmetry breaking mechanism, and also QCD modelling in the relevant topologies. This talk presents recent measurements in this sector from the ATLAS experiment.

Speaker: Josu Cantero (IFIC/UV-CSIC (ES))

QCD@LHC26_Josu.pdf

82 Vector boson scattering results in CMS

Vector boson scattering is a key production process to probe the electroweak symmetry breaking of the standard model, since it involves both self-couplings of vector bosons and coupling with the Higgs boson. If the Higgs mechanism is not the sole source of electroweak symmetry breaking, the scattering amplitude deviates from the standard model prediction at high scattering energy. Moreover, deviations may be detectable even if a new physics scale is higher than the reach of direct searches. Latest measurements of production cross sections of vector boson pairs in association with two jets in proton-proton collisions at the LHC are reported using a data set recorded by the CMS detector.

Speaker: Ruobing Jiang (Peking University (CN))

QCD@LHC_ruobing_final.pdf

83 Diboson polarisation measurements in ATLAS

The measurement of diboson polarisation states in multiboson production or vector boson scattering processes offer a new opportunity to study electroweak symmetry breaking mechanism and evolution of interaction structures over energy growth, and in particular offer connections to study predictions concerning goldstone bosons. This talk presents recent measurements in this sector from the ATLAS experiment.

Speaker: Luka Selem (IN2P3/LPNHE - Université Paris Cité)

DibosonPola_2026.pdf

Joint: New techniques & High-scale QCD

84 Monte Carlo Event Generator Modelling and Validation with Jet Measurements in CMS

The large data set collected by the CMS experiment during Run 3 enables studies of proton-proton collisions with unprecedented precision. Achieving comparable accuracy in simulation therefore requires a detailed understanding and careful validation of Monte Carlo (MC) event generators. In CMS, the hard-scattering process is typically simulated using generators such as MadGraph5_aMC@NLO and POWHEG, while the parton shower and non-perturbative evolution are modeled with generators such as Pythia and Herwig. These simulations rely on phenomenological descriptions of the underlying event, including multiparton interactions, color reconnection, hadronization, and other non-perturbative QCD effects, whose parameters are constrained through comparisons with data. This talk presents an overview of MC generator modelling in CMS, discussing recent jet physics measurements that probe different aspects of QCD modelling and provide constraints for the tuning and validation of event generators.

Speaker: Jennifer Roloff (Brown University (US))

qcdAtLHC2026.pdf

85 Gauge-Invariant Longitudinal Modes in the Herwig 7 Electroweak Parton Shower (REMOTE)

I will present a gauge-invariant treatment of longitudinal electroweak radiation in the Herwig 7 angular-ordered electroweak parton shower. In the broken Standard Model, the gauge component of a longitudinal polarisation is related by Ward identities to the corresponding would-be Goldstone mode, so a consistent shower description requires more than a purely subtraction-based prescription. Building on the existing Herwig 7 implementation, we construct a scheme in which the subtraction remainder is completed by the appropriate Goldstone contribution, yielding helicity-resolved quasi-collinear splitting kernels for fermion and vector-boson branchings while leaving the transverse sector unchanged. I will discuss the implementation and its phenomenological consequences in single- and multi-emission studies, highlighting the agreement with the default treatment at high evolution scales and the controlled differences that emerge at lower scales in channels sensitive to electroweak symmetry breaking and fermion masses.

Speaker: Aidin Masouminia (IPPP, Durham University)

GI-Modes-EWPS-Ox-AM.pdf

86 Recent progress on logarithmic accuracy in PanScales

This talk will present recent progress on demonstrable logarithmic accuracy in the PanScales parton shower project. It will discuss NNLL showers for colour-singlet processes with initial-state hadrons, and the extension of NNLL accuracy for event-shape-like and non-global observables to both PanGlobal and PanLocal showers, in a framework that consistently includes spin correlations. Finally, it will discuss how NLL accuracy is achieved for processes with heavy quarks in the final state.

Speaker: Keith Hamilton (University College London (GB))

Hamilton-QCDLHC-II.pdf

87 Recent jet substructure measurements in CMS

Measurements of jet substructure in proton-proton collisions at theLHC provide stringent tests of QCD, improve our understanding of parton showering and hadronization, and offer important tools for searches for physics beyond the Standard Model. We present recent jet substructure measurements performed by the CMS Collaboration and compare the results with a range of theoretical predictions and Monte Carlo event-generator models.

Speaker: Attila Jozsef Radl (HUN-REN Wigner Research Centre for Physics (HU))

cms_recent_jet_substructure_measurements_qcdatlhc2026.pdf

PDFs and DIS

Convener: Gitanjali Poddar (University of London (GB))

88 Interpreting Parton Distributions with Shapley Values

We present a new method to interpret PDFs using the game theoretical method of Shapley values. We use it to assess the impact of data on PDFs when determining them, and the impact of individual PDFs on collider observables. In general we recover the expected pattern of PDF sensitivity to data for modern global PDF sets. We also uncover pronounced localised losses of sensitivity that are not reflected in the uncertainty bands of the PDFs, which is potentially relevant for BSM searches. In particular we find a loss of sensitivity of the gluon PDF in the region of momentum fraction of Higgs production.

Speaker: Eva Groenendijk (University of Milan)

Shapley_talk_oxford_EG.pdf

89 MORPH: Multimodal Observables and Representations for the Physics of Hadrons

Determining high-fidelity, flexible parameterizations of hadronic parton distribution functions from experimental data remains a long-standing goal in precision phenomenology. Traditionally, this problem is addressed through dedicated, large-scale global analyses spanning hundreds of experimental datasets and conditioned on underlying theory choices such as perturbative order, potential beyond Standard Model contributions, and many other fitting assumptions. This has produced an ecosystem of PDF determinations that are connected through the underlying QCD theory, but difficult to interpolate between directly. It is within this ecosystem that we present MORPH, a foundation-model framework for learning reusable, uncertainty-aware representations of hadron structure, designed to provide a universal backbone for PDF inference across theory choices and observable modalities. MORPH currently uses self-supervised representation learning to encode ensembles of fitted PDF replicas into a structured latent space that captures the full flavor and x-dependence with calibrated uncertainty reconstruction. We benchmark this representation using a suite of machine-learning and physics-based scaling studies to determine whether it preserves the QCD information carried by the original ensembles. A central aim of MORPH is to condition this latent space on theory metadata inputs, enabling interpolation across PDF phenomenological extractions as a fast-evaluation complement to dedicated global fits. I will present progress in building this foundation-model for PDF ensembles, discuss the physics diagnostics needed to validate such representations, and outline a path toward fast, generative inverse mapping of the non-perturbative structure of the proton relevant for the next generation of particle physics experiments.

Speaker: Brandon Kriesten (Argonne National Laboratory)

Kriesten_QCDLHC26.pdf

90 Designing Precision-Oriented PDF Sets for Electroweak Measurements at Hadron Colliders

Uncertainties associated with parton distribution functions (PDFs) remain among the dominant systematic uncertainties in precision measurements of the W boson mass. A robust assessment of PDF-related uncertainties is therefore essential for future combinations of $m_W$ measurements. Drell-Yan (DY) observables, including the Z boson rapidity $y_Z$ distribution, the W boson charge asymmetry $A_W$, and the charged lepton asymmetry $A_{\ell}$, provide constraints on the parton distributions that govern the W boson rapidity $y_W$ and the lepton kinematics used in the determination of $m_W$.

In this work, the performance of several modern PDF sets for precision electroweak (EW) measurements is evaluated through a compatibility study with the aforementioned DY datasets from the ATLAS, CMS, LHCb, CDF and D0 experiments. Theory predictions are computed at NNLO in QCD with NNLL resummation using DYTurbo, and compared with the measurements through a $\chi^2$ statistic that incorporates experimental correlations and PDF uncertainties. This study will identify the PDF sets that provide the best overall description of the DY data and are therefore the most suitable candidates for future global combinations of $m_W$ measurements. In addition, PDF profiling will be performed to quantify the constraints imposed by the individual DY measurements on the parton distributions relevant for precision EW observables.

In this talk, results from the compatibility and profiling studies will be shown, demonstrating how these studies can inform the development of PDF sets tailored to high-precision EW measurements at hadron colliders.

Speaker: Baris Tuncay (University of Oxford (GB))

BarisTuncay_QCDatLHC2026.pdf

91 Analaysis of the impact on data uncertanties with the MSHT framework

We investigate the impact of modifications to the standard approach to data uncertainties in PDF fits in the context of the MSHT framework. We consider the potential for ``errors on errors'' and the consequence of this in data distributions and in fitting procedures. We also consider the degree of correlation in the treatment of correlated systematic uncertainties, and introduce a novel technique for relaxing the correlations on uncertainties determined by modelling in a physically motivated manner. We look at the impact on LHC data, with a particular emphasis on recent jet and dijet data from ATLAS and CMS.

Speaker: Dr Matthew Reader (University College London)

Matt Reader QCD4LHC2026.pdf

92 Studies of N3LO corrections and resummation scale uncertainties in fits to DIS data using xFitter

We investigate the impact of recently computed N3LO corrections to QCD splitting and deep-inelastic scattering (DIS) coefficient functions on fits of parton distribution functions (PDFs) using the xFitter framework. By comparing fits performed at different perturbative orders, we analyze the resulting modifications to the PDFs and their associated uncertainties, incorporating correlated experimental errors. The results demonstrate the importance of N3LO corrections and highlight the need for further theoretical refinement in the low-x regime. Furthermore, we study the impact of resummation-scale variations on the splitting functions and on the strong coupling constant $\alpha_{s}$. These variations introduce a significant additional uncertainty in the PDFs that has not been considered previously. We study the impact of this uncertainty on fits of HERA DIS data and its implications for predictions of top quark pair production at the LHC.

Speaker: Dr Francesco Giuli (INFN e Universita Roma Tor Vergata (IT))

FGiuli_xFitter_QCD@LHC26.pdf

10:40 Tea and coffee

Heavy Quarks

93 ATLAS results on associated top quark production (Top+X) and EFT interpretations

The high center-of-mass energy of proton-proton collisions and the large available datasets at the CERN Large Hadron Collider allow the study of rare processes of the Standard Model with unprecedented precision. Measurements of rare SM processes provide new tests of the SM predictions with the potential to unveil discrepancies with the SM predictions or provide important input for the improvement of theoretical calculations. In this contribution, total and differential measurements of associated top-quark production are shown using data taken with the ATLAS Experiment at a center-of-mass-energy of 13 TeV. These measurements provide important bounds on the electroweak couplings of the top quark, often with Effective Field Theory interpretations and constrain backgrounds that are important in searches for Higgs production and for new phenomena beyond the SM

Speaker: Oliver Rieger (Nikhef National institute for subatomic physics (NL))

011026_ATLAS_TopX_QCDLHC.pdf

94 NNLO QCD corrections to $t\bar{t}W$ production at the LHC

In this talk I will present the numerical calculation of two-loop QCD amplitude
for the associated production of a top-anti-top pair and a $W$ boson in the
leading-colour approximation.

The amplitude is expressed as linear combinations of special transcendental
functions with rational function coefficients, evaluated using differential
equations and finite-field techniques, respectively. I will highlight the main
challenges of the computation, which arise from the analytic structure of the
differential equations and the high dimensionality of the phase space.

We evaluate the finite two-loop remainder on a phase-space grid, and use it to
obtain the NNLO QCD corrections to the inclusive cross section for $t\bar{t}W$
production at the LHC.

Speaker: Vsevolod Chestnov (University of Oxford)

Chestnov_QCDLHC26.pdf

95 State-of-the-art predictions for four-top production with invariant-mass threshold resummation.

Four-top production is one of the rarest Standard Model processes observable at the Large Hadron Collider, offering sensitivity to the top-Yukawa coupling, Higgs width, and beyond-Standard-Model physics. We present precise predictions for the invariant-mass distribution and total cross section using threshold resummation at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to NLO in QCD+EW, including an assessment of theoretical uncertainties.

Speaker: Tommaso Saracco (Nikhef)

4top-QCD@LHC2026.pdf

96 Top quark mass interpretation from simulation of top-flavoured mesons

The interpretation of the top quark mass measurements in terms of well-known field theory definitions has been the topic of a long-standing discussion. In this work we reconsider this issue and simulate fictitious top-flavoured mesons, whose mass can be related to any top mass definition, such as the pole mass, by means of Heavy Quark Effective Theory. We explore final-state observables for top-pair production in $e^{+}e^{-}$ and hadron collisions, and relate the top mass in standard $t\bar{t}$ events to the pole mass extracted from top-meson samples simulated with Pythia 8.3. Our results are in agreement with the expectation of an uncertainty about $200$-$300$ MeV, hence of the order of $\Lambda_{\rm QCD}$.

Speaker: Alexander Lind (INFN Laboratori Nazionali di Frascati (LNF))

Lind_QCDatLHC2026.pdf

97 Matching flavour schemes via isolation of heavy-quark mass power corrections

Higgs production in association with quarks (QQH) offers an interesting setting to study heavy-quark mass effects and the interplay between factorisation schemes in precision QCD. We present a strategy to combine the massive- (4FS in bbH) and massless schemes (5FS in bbH) consistently at the fully differential level for fixed-order QQH predictions in a general-mass variable-flavour-number scheme (GM-VFNS).

We discuss a method to isolate power corrections in the 4FS in a gauge-invariant and fully differential manner, providing the complementary ingredient to the 5FS calculation needed for a complete description of mass effects in Higgs observables. The logarithmic contributions of the massive scheme are captured through space-like Operator Matrix Elements (OMEs), while a slicing in the heavy-quark mass isolates the constant terms and validates the matching. Subtracting these from the 4FS result leaves the genuine power corrections, which are then added to the 5FS differential predictions.

We show fixed-order results for Higgs observables at second and third order in the strong coupling constant. We conclude by discussing an alternative GM-VFNS scheme based on the ACOT formalism, which provides a different organisation of mass contributions in QQH predictions.

Speaker: Christian Biello (ETHZ)

Oxford-QQH.pdf

High-scale QCD

Conveners: Federico Buccioni (CERN), Dr Federico Sforza (University and INFN Genoa), Jennifer Roloff (Brown University (US))

98 Charm and bottom quark pair production cross sections at hadron colliders at next-to-next-to-leading-order accuracy

The inclusive cross sections for charm ($c\bar c$) and bottom ($b\bar b$) quark-antiquark pair production in proton-proton, proton-antiproton, and proton-nucleus collisions are studied over a wide range of center-of-mass energies, $\sqrt{s} = 10$ GeV--400 TeV. All existing data over $\sqrt{s} = 10$ GeV--14 TeV are collected and compared to calculations at next-to-next-to-leading-order (NNLO) accuracy using the new fixed-order MaunaKea open-source code for varying sets of parton distribution functions (PDFs). Relative to next-to-leading-order (NLO) predictions, the NNLO cross sections are enhanced by up to a factor of two, with the associated theoretical scale uncertainties reduced by the same amount, leading to agreement with experimental data over the full range of collision energies. The NNLO results are also compared with NLO predictions obtained within the SACOT-$m_T$ general-mass variable-flavour-number scheme. Despite still sizable theoretical and experimental uncertainties, $c\bar c$ cross section at multi-TeV energies can provide extra constraints on the gluon density at very small-x in global PDF analyses. In the bottom sector, more precise cross section measurements at low energies, $\sqrt{s} = 10$--100 GeV, can help constraint the bottom-quark pole mass.

Biblio: arXiv:2605.16019 [hep-ph]

Speaker: David d'Enterria (CERN)

dde_ccbar_bbbar_nnlo_qcd_at_lhc_oct2026.pdf

99 Observation of W, Z, and jet production with a tagged forward proton in proton-proton collisions at √s = 13.6 TeV

We report the first observation of the production of high-transverse-momentum jets and electroweak bosons in association with a tagged forward proton in proton–proton collisions at a center-of-mass energy of 13.6 TeV. The analysis uses 2.0 fb(^{-1}) of data collected by the CMS experiment during dedicated low-pileup LHC operation in 2026. Forward protons carrying 85–97% of the beam energy are reconstructed with the CMS Precision Proton Spectrometer and associated with centrally produced W bosons, Z bosons, or multijet systems. The signal is established through the observation of significant forward–backward asymmetries of the central system with respect to the tagged-proton direction, providing direct evidence that the proton originates from the same hard interaction. The production of W and jet events with a tagged forward proton is observed with significances exceeding five standard deviations, while the Z-boson channel is observed with a significance above three standard deviations. Fiducial tagged-proton fractions are measured inclusively and differentially as functions of jet multiplicity, W-boson charge, and multijet invariant mass, extending to central-system masses above 2 TeV. The measured rates are found to be significantly larger than predictions from current hard-diffractive models, providing new constraints on the description of diffraction and color-singlet exchange at the highest momentum transfers accessible at the LHC.

Speaker: Elisabetta Manca (CERN)

SoftQCD_QCDatLHC2026_EManca.pdf

100 Uncharted Logarithmic Structures in QCD Transverse-Energy Flow

I will discuss a new class of non-global observables defined by a veto on transverse-energy ($E_T$) flow inside an azimuthal interval $\Delta\phi$ about a chosen reference axis. Such vetoes are widely used in LHC measurements involving missing transverse momentum, yet they probe a kinematic regime whose logarithmic structure has not been explored before. We show that these observables exhibit logarithms more singular than any previously reported: both non-global logarithms (NGLs) and coherence-violating logarithms (CVLs) acquire an extra power of the large logarithm relative to standard non-global observables. I will focus on the CVL sector---computing the leading coherence-violating contribution and showing that it is enhanced from NDL to NNDL accuracy---which makes this observable an unusually sensitive probe of collinear-factorization breaking at hadron colliders. Capturing these enhanced CVLs requires resummation techniques beyond the standard non-global toolkit, which I will discuss. I will also summarize the all-orders analysis for $pp$ collisions, including analytical resummation at next-to-double-logarithmic accuracy and numerical leading-logarithmic resummation in the Veneziano limit.

Speaker: Alexander Fraley (University of Manchester)

AF.pdf

101 High-precision QCD physics at FCC-ee

The electron-positron stage of the Future Circular Collider (FCC-ee) is aiming at direct and indirect searches for physics beyond the SM in a new 91-km tunnel at CERN. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean environment provided by ee collisions, thanks to its broad span of center-of-mass energies, ranging from the Z pole to the top-pair threshold, and its huge integrated luminosities yielding jets from Z and W bosons decays respectively, pure gluon jets from Higgs boson decays, as well as O(2\times10^6) top quarks. In this contribution, we will summarize the impact that the FCC-ee will have on our improved knowledge of the strong force including: (i) QCD coupling determinations with permil uncertainties, (ii) ultraprecise studies of parton radiation and jet properties (ligh-quark/heavy-quark/gluon discrimination, jet substructure, etc.); and (iii) accurate scrutiny of nonperturbative QCD phenomena (color reconnection, hadronization, final-state hadron interactions,...).

Speaker: Rene Poncelet (IFJ PAN Krakow)

2026.10.01-Oxford-FCCee-poncelet.pdf

Joint: New techniques & Higgs, EW, and BSM

Convener: Daniel Winterbottom (Imperial College (GB))

102 Hunting the unseen: Boosting Semi-Visible Jet via Jet Substructure metrics

In the study of dark matter detection at colliders, novel candidates have emerged to bridge between experimental data and theoretical models. Dark Showers (DS) are being studied as an extension of the Standard Model (SM), containing both invisible and visible particles that allow us to predict scenarios involving collider observables. Among these, Semi-Visible Jets (SVJs), represent a novel promising new signature, particularly those mediated by a massive $Z^{\prime}$ boson that enables the production of heavy dark hadrons. In such a scenario, jets enclose visible SM particles and invisible dark matter components, having more Missing Transverse Energy $E_{T}^{miss}$ (MET). The complexity is further heightened since the poorly constrained nature of the dark sector; factors such as the dark confinement scale, dark meson masses and the fraction of the invisible DM hadrons, our study will review different tools at the jet-substructure level to study Semi-Visible Jets (SVJs), formed by the decay of a resonant heavy gauge boson $Z^\prime$. We characterise the leading jet using substructure metrics such as the Energy-Energy Correlation Functions (EECs), angularities, charged hadrons multiplicity and the Lund Jet Plane (LJP) as kinematical features with modern approaches at the MET including the global MET distribution and the difference on the azimuthal angle of the leading jet and the global MET.

Speaker: Mr Miguel Angel Avendano Bernal (University of Southampton)

QCD@LHC_slides_v1.pdf

QCD@LHC_slides_v1.pptx

103 MiNNLOps for ttH: first NNLO+PS predictions at the LHC

We present the first NNLO+PS simulation of Higgs-boson production in association with a top-quark pair ($t \bar t H$) at the LHC.
The calculation is performed within the MiNNLOps framework and combines NNLO QCD corrections with parton-shower effects in a fully differential Monte Carlo event generator (publicly available).
Since the exact two-loop amplitude is not yet known, we employ two complementary approximations based on the soft-Higgs and high-energy limits, respectively. The latter is constructed in full colour for the first time, and both approximations are combined pointwise across phase space.
After thorough validation, we present event simulations for inclusive and fiducial observables, including LO effects from Higgs decays into photons and off-shell top-quark decays. We discuss the impact of NNLO corrections and parton-shower effects on a selection of relevant observables.

Speaker: Chiara Savoini (Technical University of Munich (TUM))

Savoini_QCD@LHC26.pdf

104 NNLO+PS Higgs-pair production in MiNNLOPS

While many of the Higgs couplings have already been measured with remarkable precision, the structure of the Higgs potential is still largely unconstrained. In this context, Higgs-boson pair production plays a special role, as it provides direct access to the Higgs self-coupling.
In this talk, I will present results for Higgs-boson pair production in gluon fusion at hadron colliders at next-to-next-to-leading-order (NNLO) QCD matched to parton showers within the MiNNLOPS framework. Since the full top-quark mass dependence at this order is not available, I will show how finite top-quark mass effects can be incorporated through different approximations using the available amplitudes in the full theory and I will discuss their impact on different observables. I will also compare the results with existing NNLO calculations matched to parton showers from GENEVA and present phenomenological results for different Higgs-decay channels and variations of the trilinear Higgs coupling.

Speaker: Francesco Garosi (Max Planck Institut für Physik)

Garosi_QCD@LHC.pdf

105 Resonance aware MC@NLO QCD+EW matched parton showers

Parton showers are an essential feature of event generation that provide a numerical resummation of the large logarithms that enhance soft and collinear radiation. Matching them to higher order calculations requires careful treatment in order to avoid double-counting real radiation and preserve fixed order accuracy through matching algorithms such as MC@NLO. As we approach HL-LHC, there is a need for increasing precision of theoretical predictions so the inclusion of NLO EW alongside QCD corrections and matching to a QED shower becomes necessary. QED parton showers present addition complications, including the potential for negative splitting kernels and many more spectators to each splitting. In a dipole implementation, these spectators absorb the recoil required to satisfy momentum conservation and on-shell conditions in each splitting, however this 'reshuffling' of momenta can lead spurious, and potentially large, higher order effects if it occurs across a resonance. Thus, the need for a resonance-aware implementation is much greater for a QED shower than QCD due to the expanded set of spectators.

I will present the first implementation of automated interleaved QCD+EW matching, using the MC@NLO method in the event generator Sherpa, along with an approach to treat resonances by factorising the parton shower into production and decay for hard emissions, using Drell-Yan to illustrate the cases of both a neutral and charged resonance.

Speaker: Joanne Roper (Durham University)

QCDLHC_Roper.pdf

12:50 Lunch

Higgs, EW, and BSM

Conveners: Dr Alexander Karlberg (CERN), Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Daniel Winterbottom (Imperial College (GB)), Mika Anton Vesterinen (University of Warwick (GB))

106 Gauge Boson Polarization as a Probe of SMEFT Effects in Production

Diboson production at the LHC provides a powerful probe of the electroweak sector and possible deviations from the Standard Model within the Standard Model Effective Field Theory (SMEFT). We present a study of the interplay between dimension-6 SMEFT operators and gauge boson polarization in production at $\sqrt{s}$ = 13 TeV.

The analysis is based on dedicated Monte Carlo event samples generated with MadGraph, enabling a controlled investigation of different polarization configurations and EFT contributions. We perform a systematic comparison between Standard Model and SMEFT predictions using a broad set of kinematic and angular observables, with particular emphasis on polarization-sensitive variables and their discriminatory power.

In addition, we investigate analysis strategies aimed at enhancing sensitivity to EFT effects, including multivariate techniques that exploit correlations among observables. These methods provide complementary information to traditional analyses and offer guidance for optimized polarization measurements.

This work demonstrates the potential of polarization observables as sensitive probes of EFT effects and contributes to the development of analysis frameworks for future precision studies at the LHC.

Speaker: Dr Maryam Bayat Makou (Southern Methodist University)

Polarization_QCD@LHC.pdf

107 Searches for BSM Higgs and Additional Scalars at ATLAS

Searches for BSM Higgs and Additional Scalars at ATLAS The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable of explaining some observations by itself. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs bosons, additional scalars, or beyond-the-Standard-Model couplings to the Higgs boson. In this talk, the latest searches for BSM Higgs and additional scalars are reported.

Speaker: Qichen Dong (University of Oxford (GB))

QCDLHC26_vfin.pdf

108 Searches for New Resonances with CMS

The quest for new physics is a major aspect of the CMS experimental program. This includes models involving resonances that can decay to photons, leptons or jets. This talk presents an overview of such analyses with an emphasis on new results and the novel techniques developed by the CMS collaboration to boost the search sensitivity. The searches are carried out with data of the Run-II and Run-III of the LHC in proton-proton collisions with the CMS detector.

Speaker: Irene Andreou (University of Cyprus (CY))

SearchesforNewPhysics_QCDatLHC_IreneAndreou.pdf

109 Searches for SUSY, Dark Matter, and Heavy Resonances at ATLAS

Many theories beyond the Standard Model predict new phenomena giving rise to observable final states. Examples include Supersymmetry, Z' or W' bosons, KK gravitons, vector-like quarks/leptons or heavy leptons, or Dark Matter. Searches for new physics with such signatures, produced either resonantly or non-resonantly, are performed using the ATLAS experiment at the LHC. This talk will report the most recent ATLAS results.

Speaker: Sukanya Sinha (The University of Manchester (GB))

SSinha_ATLAS_BSMsearches_QCDLHC2026.pdf

110 Searches for dark sector signatures with CMS

Among the intriguing scenarios of new physics that provide explanation to several shortcomings of the Standard Model (SM), hidden valley scenarios include a Dark Sector that extends the SM with a non-Abelian gauge group, similar to quantum chromodynamics with new matter and gauge fields analogous to the SM quark and gluon fields. This may result in a rich phenomenology which we can access through portal interactions. In this talk we present the most recent results from CMS that explore such Dark Sectors by exploiting dedicated data streams and innovative usage of the CMS detector.

Speaker: Jaime Leon Holgado (CERN)

261001_DarkSector_QCD26_JLH.pdf

Joint: Heavy Quarks & Low-scale QCD

111 Recent results in Lambda and Ks production cross sections at LHCb

Recent LHCb measurements of the differential production cross-sections of prompt $K_S^0$ and $\Lambda$ hadrons in proton--proton collisions are presented. The production cross-sections and the $\Lambda/K_S^0$ production ratio are measured at centre-of-mass energies of $\sqrt{s}=13$ and $13.6\,\mathrm{TeV}$ as functions of rapidity and transverse momentum in the forward region. The results are compared with theoretical calculations, event-generator predictions, and previous experimental measurements.

Speaker: Noah Albin Behling (TU Dortmund University (DE))

QCD@LHC_LHCb_V0_NB_01102026.pdf

112 Heavy-flavour production in heavy-ion collisions with ALICE

Heavy-ion collisions at the Large Hadron Collider (LHC) provide a unique environment for probing the properties of the quark-gluon plasma (QGP), a deconfined state of strongly interacting matter in which quarks and gluons are not bound into hadrons. Heavy quarks (charm and beauty), produced predominantly in the initial hard-scattering processes, traverse the full evolution of the medium and act as privileged probes of its characteristics.

This contribution presents the latest ALICE results on heavy-flavour production in heavy-ion collisions. Measurements of open heavy-flavour hadrons constrain the modelling of energy loss and diffusion of heavy quarks in the QGP, probing the mass dependence of parton–medium interactions. Measurements of elliptic and higher-order flow coefficients of heavy-flavour hadrons provide evidence for charm-quark thermalization and participation in the collective expansion of the medium. Quarkonium production, of both ground and excited states, is discussed in terms of colour screening and regeneration mechanisms, which are sensitive to quarkonium binding energies and the temperature of the QGP. Complementary measurements of coherent photoproduction of quarkonia in ultra-peripheral Pb-Pb collisions are also discussed as a tool to access the gluon distribution in nuclei.

These observables combined provide a comprehensive picture of heavy-quark transport, hadronisation, and quarkonium production in the QGP.

Speaker: Luigi Dello Stritto (Austrian Academy of Sciences (AT))

QCD2026_ldellost_final.pdf

113 Heavy flavour production with SMOG2

The majority of charm quarks are produced in the initial stages of the collision. In heavy-ion collisions, this makes final-state particles containing charm quarks ideal probes of the formed medium, its effects, and its evolution. Charmonium states are among the most important probes of the deconfined QCD matter. A complete understanding of their production and interaction with the medium created in the collision is necessary to disentangle genuine hot-matter effects from cold nuclear matter effects. Furthermore, the presence of a nuclear environment may affect the hadronisation mechanism of charm
quarks, potentially leading to an asymmetry in the production of open-charm mesons. To quantify these effects, charm-hadron production must be measured in different collision systems over a wide energy range. Fixed-target collisions at LHCb, enabled by the SMOG2 system, complement studies performed in collider mode and provide access to kinematic regions not explored by other fixed-target experiments. In Run 3, the SMOG2 system has allowed for an expanded set of targets, including H2, D2, He, CH4, O2, Ne, Ar, and Xe, the former serving as a proxy for pp collisions at √sNN = 113 GeV. Here we present the first LHCb fixed-target heavy-flavour results from Run 3 and discuss the prospects for upcoming analyses aimed at improving the precision of and extending the Run 2 results. These results highlight the unique opportunities offered by the LHCb fixed-target programme
for studying quarkonium production, open-charm hadronisation, and nuclear matter effects, advancing our understanding of QCD matter under extreme conditions.

Speaker: Aleksandra Petkovic (Laboratoire Leprince-Ringuet, Ecole polytechnique)

QCD@LHC_APetkovic.pdf

114 Isolating Unisolated Upsilons with Anomaly Detection in CMS Open Data

We present the first study of anti-isolated Upsilon decays to two muons (Υ→μ+μ−) in proton-proton collisions at the Large Hadron Collider. Using a machine learning (ML)-based anomaly detection strategy, we "rediscover" the Υ in 13 TeV CMS Open Data from 2016, despite overwhelming anti-isolated backgrounds. We elevate the signal significance to 6.4σ using these methods, starting from 1.6σ using the dimuon mass spectrum alone. Moreover, we demonstrate improved sensitivity from using an ML-based estimate of the multi-feature likelihood compared to traditional "cut-and-count" methods. Our work demonstrates that it is possible and practical to find real signals in experimental collider data using ML-based anomaly detection, and we distill a readily-accessible benchmark dataset from the CMS Open Data to facilitate future anomaly detection developments.

Speaker: Radha Mastandrea

QCD@LHC 2026 (3).pdf

115 The ALADDIN experiment at LHC

ALADDIN (An LHC Apparatus for Direct Dipole moments INvestigation, https://aladdin.web.cern.ch/) is a proposed compact fixed-target experiment at the LHC, designed to enable precise measurements of charm baryon electromagnetic dipole moments. The experiment leverages an innovative storage-ring layout that redirects protons from the beam halo onto a solid target, coupled with a bent crystal. This setup produces forward-boosted charm baryons, which are then channeled through the crystal. By exploiting spin precession induced by the channelling effect in the bent crystal, ALADDIN aims to measure both the magnetic and electric dipole moments through an analysis of the polarization of decaying charm baryons. The experimental apparatus consists of a 4.4 m-long spectrometer and a 20 m-long RICH detector for particle identification. It is designed for installation in the LHC Insertion Region 3 during Long Shutdown 3 (and onwards), requiring no civil engineering and having minimal impact on LHC operations, with data-taking planned for Run 4+5. A proof-of-principle test at the LHC, TWOCRYST (https://twocryst.web.cern.ch/), has concluded several successful dedicated machine development runs in 2025 and 2026 ,before LS3. TWOCRYST demonstrated the feasibility of the concept and detailed data analysis is ongoing. The experiment’s Letter of Intent has been submitted to the LHCC (https://cds.cern.ch/record/2905467), which has approved the collaboration to proceed with a technical proposal in 2026-2027.

Speaker: Paolo Gandini

gandini_ALADDIN.pdf

Joint: New techniques & Amplitudes

116 Three-loop full-color QCD corrections to Higgs-plus-jet amplitudes (REMOTE)

Higgs-plus-jet production provides direct access to Higgs production at nonzero transverse momentum. In this talk, I will present our calculation of the three-loop full-color QCD corrections to the Higgs-plus-jet amplitudes in the heavy-top limit.

Speaker: Xin Guan (SLAC)

20261001 QCD@LHC 2026 Xin Guan.pdf

117 Taking the First Steps Toward Higgs Production at N4LO in QCD

We present recent progress toward the inclusive gluon-fusion Higgs-boson and Drell–Yan cross sections at next-to-next-to-next-to-next-to-leading order (N4LO) in perturbative QCD. Our main results concern the single-real contributions, involving three QCD partons together with a Higgs boson or virtual photon. These comprise the interference of one- and two-loop amplitudes and, in the generalized leading-color limit, the interference of tree-level and three-loop amplitudes. The results are expressed as Laurent expansions in the dimensional regulator (\epsilon), with coefficients given by analytic functions of the ratio of the color-singlet invariant mass to the partonic center-of-mass energy.
We also discuss recent progress on the double-real-emission contributions in the strict threshold limit, providing further ingredients toward a complete N4LO prediction. Beyond their phenomenological relevance, these calculations offer a laboratory for studying analytic complexity that arises at high perturbative order.

Speaker: Adi Suresh (SLAC)

QCD@LHC2026.pdf

118 Two-loop QCD corrections for Higgs plus two-jet production through gluon fusion

We present two-loop scattering amplitudes in QCD for the hadronic production of a Higgs boson in association with two jets mediated by the top-quark Yukawa coupling.
Our results cover the dominant contributions for all partonic channels, which are computed in the heavy top-mass limit in the leading-color approximation.
We obtained analytic expressions of the amplitudes decomposed in an integral basis by reconstructing the integral coefficients from numerical evaluations in finite fields.
To handle the amplitudes' complexity, we exploited their analytic properties, reducing the required number of samples for the reconstruction and leading to compact representations.
Finally, we studied the singularity structure of the amplitudes and find surprising non-analytic behaviour in the bulk of the physical phase space.

Speaker: Viktor Kuschke (Paul Scherrer Institut, Universitaet Zuerich)

QCDLHC_VK.pdf

119 Two-loop Feynman integrals for ttgamma hadron production in the leading colour approximation

We complete the calculation of the two-loop Feynman integrals required to obtain next-to-next-to-leading order (NNLO) QCD predictions for on-shell top-antitop production in association with a photon at hadron colliders in the leading-colour approximation.
The integrals computed here are also relevant to the subleading-colour contributions to top-antitop production in association with a jet.
Due to the complex kinematic structure of the process, involving six independent kinematic invariants, and the appearance of up to three massive propagators in the master integrals, the algebraic complexity of the latter increases dramatically, giving rise to sectors containing nested square roots and elliptic integrals.
To address these challenges and compute the master integrals using the method of differential equations (DEs), we employ finite-field techniques for the reconstruction of the connection matrix entries and construct suitable bases for each family, avoiding the introduction of transcendental functions in their definition. In these bases, the DEs are $\varepsilon$-factorised in the logarithmic sectors, linear in $\varepsilon$ for sectors with nested square roots, and quadratic in $\varepsilon$ for the elliptic sectors.
We perform the Laurent expansion in terms of a potentially overcomplete set of special functions, evaluated through numerical solution of DEs.

Speaker: Federico Ripani

qcd@lhc26.pdf

120 Efficient Calculation of Soft functions

Over the past several years, a collection of techniques have enabled the efficient computation of new soft and beam functions at NNLO. In this talk, I show how we have used some of those techniques to compute new soft functions at NNLO, firstly for generalised event shapes at $e^+e^-$ colliders, and secondly for the measurement of boson transverse momentum along with a rapidity-dependent jet veto at hadron colliders. Our focus is to make the calculation as simple as possible, and to make full use of existing results, in order to pave the way for higher-order calculations, and more differential observables.

Speaker: Jonathan Richard Gaunt (University of Cyprus)

QCD@LHC 2026_Gaunt.pdf

15:40 Tea and coffee

Joint: Heavy Quarks & Low-scale QCD

121 Recent Heavy-Flavor Spectroscopy and Rare Decay Results from ATLAS

This talk presents recent ATLAS results in heavy-flavor spectroscopy and rare decay searches. Highlights include studies of excited Bc meson states and resonance structures in the J/ψψ(2S) system, providing new insight into heavy-quark bound states and exotic hadron spectroscopy. Selected searches for rare decays are also discussed, extending the sensitivity of ATLAS to physics beyond the Standard Model.

Speaker: Yuxuan Zhang (Tsinghua University (CN))

HF_RD_ATLAS_Yuxuan.pdf

122 Recent results of hadron spectroscopy at LHCb

Hadron spectroscopy plays a central role in deepening our understanding of the low-energy and non-perturbative regime of the strong interaction. Excited hadrons can be produced in heavy-hadron decays when kinematically allowed. In such processes, amplitude analysis provides a powerful technique to disentangle contributions from different resonances and to determine their spin-parity quantum numbers by exploiting angular-distribution information. This talk will cover recent results in hadron spectroscopy at LHCb, including but not limited to those obtained with amplitude-analysis techniques.

Speaker: Chen Chen (Cavendish Laboratory, University of Cambridge)

lhcb_hadron_spectroscopy_chenchen.pdf

123 Excited heavy mesons and exotics from lattice QCD

In recent years there has been a lot of progress in studying excited and exotic hadrons, resonances and scattering using first-principles lattice QCD calculations. I will discuss a selection of work on charm and charmonium-like mesons such as results relevant for the exotic $T_{cc}$, $T_{cs}$ and $T_{c\bar{s}}$ observed by LHCb, the $D^{*}_{0}(2300)$ and enigmatic $D^{*}_{s0}(2317)$ charm mesons, and scalar and tensor charmonium resonances.

Speaker: Christopher Thomas (University of Cambridge)

CThomas_QCD_LHC_Sept2026.pdf

124 Recent results in seaches for tetraquark states in CMS

The spectroscopy of exotic hadrons provides a unique opportunity to investigate the dynamics of Quantum Chromodynamics (QCD) in the non-perturbative regime. The large data samples collected by the CMS experiment during LHC Run 2 and Run 3 have enabled high-precision studies of multiquark candidates in several heavy-quark systems.

Recent CMS measurements have established the existence of multiple fully charmed tetraquark candidates in the (J/ψ,J/ψ) invariant-mass spectrum. The analysis reveals three resonant structures, (X(6600)), (X(6900)), and (X(7100)), with significances exceeding the observation threshold, and provides evidence for quantum interference effects among the resonances, offering new insight into the spectroscopy and internal structure of fully heavy multiquark states.

In addition, CMS has recently reported the observation of a resonant structure in the (Υ(1S)φ(1020)) final state, opening new investigations into study exotic states containing both beauty and strangeness. This measurement extends the experimental exploration of tetraquark spectroscopy into a previously unexplored sector and provides valuable input for theoretical descriptions of multiquark dynamics.

Together, these measurements demonstrate the outstanding potential of the CMS experiment for precision spectroscopy and establish a new benchmark for understanding the spectrum of exotic hadrons in high-energy proton--proton collisions.

Speaker: Adriano Di Florio (Centre National de la Recherche Scientifique (FR))

QCD@LHC_CMS_Tetraquarks_Adriano.pdf

125 All-charm tetraquarks at hadron colliders: A high-precision fragmentation perspective

We present a systematic study of all-charm tetraquark fragmentation in high-energy hadronic collisions within a heavy-flavor fragmentation framework in QCD. As part of this program, we construct the TQ4Q2.0 fragmentation functions by consistently incorporating, for the first time, all leading-power partonic fragmentation channels. The calculation combines updated NRQCD-inspired initial-scale inputs with threshold-aware DGLAP evolution implemented through the Heavy-Flavor NonRelativistic evolution (HF-NRevo) scheme. A replica-based uncertainty-quantification strategy incorporating missing-higher-order and long-distance matrix-element uncertainties is implemented, leading to evolved fragmentation-function grids released in LHAPDF6 format. This work promotes a precision-QCD and collider-oriented description of multiquark production dynamics, providing a systematic framework relevant to the interpretation of recent all-charm tetraquark observations at the LHC and to future investigations at next-generation colliders.

Speaker: Dr Francesco Giovanni Celiberto (UAH Madrid)

talk_QCD@LHC_2026_Celiberto_TQ4Q20.pdf

Joint: New techniques & Amplitudes

126 Local Infrared Factorisation: a Road to Numerical Scattering Amplitudes

A detailed picture of the infrared factorisation properties of scattering-amplitude integrands can be exploited to derive finite-remainder representations which are amenable to direct numerical integration. This provides an alternative to the usual analytic approaches. In this talk, I will present a proof-of-concept result: integrand representations for generic two-loop QED amplitudes which exhibit local factorisation in all soft and collinear limits. I will also discuss a corresponding local IR subtraction formula, which enables their direct numerical integration, and elaborate on obstacles and ideas for generalisations to QCD.

Speaker: Dr Giulio Gambuti (ETH Zurich)

slides.pdf

127 Feynman integral relations from infrared singularities

Precision predictions for LHC processes at NNLO and beyond rely on the efficient reduction of multi-loop Feynman integrals to a small set of master integrals, a task that becomes increasingly computationally expensive as the number of loops and external legs grows. We present a new strategy that constructs integration-by-parts relations directly from the soft and collinear singularities of the integral family. We show that these singularities give rise to compact determinantal syzygies with controlled propagator powers, thereby translating the singularity structure directly into efficient reduction identities. We demonstrate the method for the planar two-loop five-point integral families relevant to $pp \to t\bar{t}H$, a benchmark multi-scale $2 \to 3$ process of direct relevance to precision phenomenology at the LHC. The construction can be systematically extended to the increasingly complex integral topologies encountered in scattering amplitudes, offering a practical route to the multi-loop, multi-leg calculations required for future precision studies at the LHC.

Speaker: Federico Coro (Ghent University)

fcoro_qcdlhc.pdf

128 Leading Singularities and Canonical Bases Beyond Polylogarithms

By now, using differential equations rather than direct integration has become a standard method for computing multi-loop Feynman integrals. The notion of canonical bases, where these differential equations take a particularly simple form, is well understood for integrals that evaluate to multiple polylogarithms. In particular, it is well-known that canonical integrals can be understood as integrals with constant leading singularities, where the latter can be computed purely from the integrands. However, there are many known examples of Feynman integrals that do not evaluate to polylogarithms, where these concepts are more subtle, if defined at all. In this talk, I will elaborate on the connection of integrand analysis, leading singularities and canonical bases beyond polylogarithms, and apply these concepts to self-energies in QED and QCD.

Speaker: Felix Forner (TUM)

Forner_QCD@LHC26.pdf

129 QCD–Gravity Duality and Discrete BFKL Evolution in Multi-Regge Kinematics

We present a novel approach to computing duality relations between Quantum Chromodynamics (QCD) and gravity in the Multi-Regge Kinematics (MRK) limit. This framework leverages Mathematica-based tools—FeynArts, FeynCalc, and FeynGrav—with a new implementation that integrates FeynGrav into FeynArts, enabling significantly faster generation of gravity diagrams. We outline the procedure through which duality relations naturally emerge, focusing on the conceptual structure rather than technical detail. Within the same MRK framework, we also present recent results on a discretized formulation of the BFKL equation. By constructing recursion relations, we describe the evolution of the gluon Green function and establish a connection with the Knizhnik–Zamolodchikov equation. This approach reveals the appearance of Harmonic Polylogarithms and leads to a direct link with anomalous dimension coefficients, which we successfully recover within our formalism.

Speaker: Josep Rubi Bort (Instituto de Física Teórica (IFT))

JRB_DCS_BFKL.pdf

130 Tropical Monte Carlo Integration

I will present the method of tropical Monte Carlo integration for scalar Feynman integrals in the software feyntrop. In order to apply this approach in the physical regime, I introduce a parametric representation of Feynman integrals that implements the causal $i\varepsilon$ prescription concretely while retaining projective invariance. feyntrop can efficiently evaluate dimensionally regulated, quasi-finite Feynman integrals, with not too exceptional kinematics in the physical regime, with a relatively large number of propagators and with arbitrarily many kinematic scales. I will review some of the mathematical ingredients for tropical Monte Carlo integration and discuss new upgrades being made to feyntrop.

Speaker: Felix Tellander (Trinity College Dublin)

Talk_Tropical.pdf

PDFs and DIS

Convener: Gitanjali Poddar (University of London (GB))

131 The 3-loop variable flavor number scheme (REMOTE)

We describe the variable flavor number scheme to three-loop order, which modifies
the massless parton densities by single- and two-mass effects and introduces heavy-quark
parton distribution functions for charm and bottom. A renormalization group analysis
shows the validity of this picture at large scales $Q^2$, where it resembles the
non-power-suppressed heavy-flavor corrections completely. We also provide numerical
implementations of a series of charged and neutral current Wilson coefficients

Speaker: Prof. Johannes Bluemlein (DESY)

OXFORD26.pdf

132 On the N3LO evolution of the PDFs from moments

The N3LO evolution of the PDFs is one of the required ingredients for percent-level precision phenomenology at the HL-LHC.
This talks reviews the progress in parameterising the evolution kernels by computing analytically a set of the moments of these quantities and imposing physical constraints.

Speaker: Giulio Falcioni

falcioni.pdf

133 On recent extractions of TMD distributions

In this talk, I will discuss the current status of TMD extractions.I will highlight recent progress, including neural-network parameterisations, applications to precision measurements of the strong coupling and the W boson mass, and the extraction of gluon TMDs from LHC data.

Speaker: Dr Valerio Bertone (C.E.A. Paris-Saclay)

bertone_QCDatLHC_Oxford_01_10_2026.pdf

134 Status of Nuclear PDF Determinations

Nuclear parton distribution functions (nPDFs) are a key ingredient for precision studies of high-energy nuclear collisions. This talk will review the current status of global nPDF analyses, focusing on recent determinations including EPPS21, nNNPDF3.0, and nCTEQ26. We will discuss the impact of new experimental constraints, similarities and differences between the various fitting frameworks, and the resulting uncertainties on parton distributions in nuclei. Special attention will be paid to the strange-quark and gluon distributions, as well as to the nuclear (A) dependence.

Speaker: Prof. Michael Klasen (University of Münster)

135 Constraining proton structure and deuteron effects at large x: the CJ26 global analysis

We present CJ26, the latest CTEQ-JLab global QCD analysis, which simultaneously determines the proton parton distribution functions and nuclear corrections in deuteron targets. The analysis includes, for the first time in a global fit, the full JLab 6 GeV inclusive DIS dataset together with the first published measurements from the 12 GeV era. Focusing on the large-xx region, we examine the interplay between higher-twist contributions and nucleon off-shell effects in low-energy proton and deuteron data, and assess their impact on the extracted quark and gluon distributions. We also demonstrate the importance of a careful treatment of correlated experimental systematic uncertainties for obtaining high-precision PDF determinations, and discuss how future measurements will further improve our understanding of nuclear effects and the partonic structure of light nuclei.

Speaker: Matteo Cerutti (CEA Paris-Saclay)

Cerutti_QCD@LHC.pdf

18:30 Pre-dinner drinks

19:15 Conference dinner

Friday 2 October

Plenary

Convener: Stefano Forte (Università degli Studi e INFN Milano (IT))

136 Higgs, Electoweak, and Beyond at the LHC

Speaker: Chris Pollard (University of Warwick (GB))

QCDLHC20261002.pdf

137 Global fits of the Standard Model and beyond

Speaker: Laura Reina

qcdlhc26.pdf

138 AI and collider physics

Speakers: Tilman Plehn, Tilman Plehn (Heidelberg University)

oxford_26.pdf

10:30 Tea and coffee

Plenary

Convener: Matteo Cacciari (LPTHE Paris)

139 Recent developments in heavy-ion physics

Speakers: Dr Guilherme Milhano (LIP-Lisbon & CERN TH), Guilherme Teixeira De Almeida Milhano

qcdatlhc2026_MILHANO.pdf

140 Heavy ions and fixed-target measurements at LHCb

Speaker: Michael Winn (Université Paris-Saclay (FR))

presentation_QCDatLHC-4.pdf

141 Overview of ALICE results

Speaker: Maximiliano Puccio (CERN)

261002-mpuccio-alice-highlights.pdf

142 Status of the EIC

Speakers: Abhay Deshpande, Abhay Deshpande (Stony Brook University)

EIC.QCD@LHC2026.Oxford.present.pdf