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FAKT Workshop 2024: Particle Physics Retreat
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Europe/Vienna
Description
This workshop serves as a platform to get to know the nuclear and particle physics community in Austria, to connect the participating institutes, to network, and to strengthen the existing collaborations.
The workshop takes place in the JUFA hotel in Bruck an der Mur: https://www.jufahotels.com/hotel/bruck-an-der-mur/
The meeting starts on Thursday with Lunch at 12:30 and ends on Friday after Lunch.
For booking a room, please send an email to r.bruck@jufahotels.com with the subject "Zimmerreservierung 'Österreichische Akademie der Wissenschaften"'22.2.-23.2." and provide name, address, and date of birth.
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12:30
Lunch
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Talks: Afternoon session
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1
WelcomeSpeaker: Massimiliano Procura (University of Vienna (AT))
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2
HEP Instrumentation: From ECFA Detector roadmap to DRD Collaborations
The 2020 update of the European Strategy for Particle Physics included the mission to the European Committee for Future Accelerators (ECFA), to develop a global Detector R&D Roadmap defining the backbone of detector R&D required to deploy the community’s vision for the future HEP experiments reaching up to the FCC-hh. Based on this 200-pages document, CERN was ask to host Detector R&D (DRD) Collaborations, driving these developments forward, so that Instrumentation is not the limiting factor to meet the needs of the long-term European particle physics program.
In this presentation, I review the content of the ECFA Detector R&D Roadmap and show how the new DRD collaborations have been implemented.Speaker: Thomas Bergauer (Austrian Academy of Sciences (AT)) -
3
Exploring long-lived particles decaying into displaced dimuons at $\sqrt s = 13.6$ TeV : Innovative Triggers for Enhanced Sensitivity at the CMS Experiment
This talk presents an inclusive search for long-lived exotic particles decaying to a pair of muons. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex that is displaced from the proton-proton interaction point by distances ranging between several hundred micrometers to several meters. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}=13.6$ TeV in 2022, corresponding to an integrated luminosity of 36.6 $\text{fb}^{-1}$, using new trigger algorithms designed to maximize sensitivity to such events. The results of the search are interpreted in the framework of the hidden Abelian Higgs model and an R-parity violating supersymmetry model, and show substantial improvements from the analysis performed using data taken at $\sqrt{s}=13$ TeV in 2016 and 2018.
Speaker: Mangesh Sonawane (Austrian Academy of Sciences (AT)) -
4
Global LHC constraints on electroweakinos with SModelS v2.3
The lack of experimental evidence for new physics in the LHC data puts stringent constraints on supersymmetric theories. However, supersymmetric particles at the LHC are searched for in a channel-by-channel fashion, in specific final states, and the results are typically presented in the context of simplified models. It is therefore important to attempt at a more global reinterpretation of the results of these searches in the context of realistic theoretical scenarios. The SModelS tool allows for a fast reinterpretation of LHC searches for new physics on the basis of simplified model results. So far, such reinterpretation has also mostly been conducted in a channel-by-channel approach, considering the results from each experimental search separately. In this presentation, we go a step further and discuss how combining LHC search allows us to formulate a global likelihood which results in better and statistically more robust constraints on the tested models. We further focus on the electroweakino sector of the MSSM, for which we derive global constraints based on the ~15 publicly available and reusable ATLAS and CMS searches for signals in this sector through the SModelS package.
Speaker: Ms Sahana Narasimha (HEPHY, Vienna) -
5
From colour evolution to hadronization and electroweak final states
Predictions for exclusive final states from first principles are constrained to low multiplicity. Otherwise they are intractable and phenomenological models are used. This applies, first and foremost, to hadrons due to the strong interaction. However, electroweak objects at high energies are not too dissimilar and require an accurate treatment across these two regimes. In this contribution I will outline some recent work on (colour) evolution in QCD and the idealistic quest for such an extrapolation. I will then sketch how these ideas generalize to the electroweak sector, with emphasis on the definition of external states.
Speaker: Simon Plätzer (University of Graz (AT)) -
6
Reshaping BSM model building & news from Graz
Gauge invariance beyond perturbation theory has been found to substantially and qualitatively alter even basic spectroscopy. This has been confirmed in lattice simulations. The mechanism by Fröhlich, Morchio, and Stroccchi allows an analytical description of these findings.
These features are introduced, and especially their implications for grand-unified theories/leptoquarks and supersymmetry are elucidated, where experimental searches need to be substantially altered.
Speaker: Axel Torsten Maas -
7
Defining the Monte Carlo top quark mass parameter
The currently most precise top quark mass determinations, called direct measurements, represent determinations of the Monte-Carlo top quark mass parameter from observables which can only be simulated and for which no first principles QCD computations exist. This leads to an overall ambiguity of the interpretation of these measurements (in terms of a well-defined top mass renomalization scheme) of around 500 MeV. I show what it needed to address this problem in a systematic way in the context of Monte-Carlo-based top mass measurements. I demonstrate the approach explicitly for the case of the 2-jettiness distribution for top pair production at electron-positron collisions.
Speaker: Andre Hoang (Austrian Academy of Sciences (AT)) -
8
Beyond the Narrow-Width Limit for Off-Shell and Boosted Differential Top Quark Decays
The two canonical approaches to describing top quark decay are on the one hand calculations in the narrow-width (NW) limit and on the other hand full off-shell fixed-order computations. The NW limit allows one to factorise the production and the decay process and thus to treat the top quark as an on-shell particle such that the spin-density formalism can be applied. Full off-shell fixed-order calculations take into account both resonant and non-resonant effects as well as non-factorisable contributions, as a result the computations are more involved, in particular when including QCD corrections.
In our work we pursue a factorised approach that includes the spin-density formalism and allows for the description of off-shell effects of the top quark within the effective field theory treatment of soft-collinear effective theory (SCET), which thus can also be used for resummation. Our approach relies on boosted top quark production, where the decay products are in the top quark resonance region. In this talk I will introduce the theoretical ingredients to describe top quark decay in SCET. I will then illustrate at tree-level the calculation of two differential observables using this framework.
When including QCD corrections we pursue a semi-analytic approach, where effects related to the top quark decay can be treated numerically, while the resummation can still be performed in an analytic setting.
Speaker: Ines Ruffa -
9
Factorization of Inclusive Semileptonic Off-Shell and Boosted Top Quark Decays in the Endpoint Region
Due to its large mass the top quark plays an important role in consistency checks of the Standard Model and new-physics searches. Studies concerning precise theoretical predictions of the top production and its decay are commonly based on the narrow-width (NW) limit of the top quark propagator or on full off-shell computations. Starting with a short introduction to effective field theories, I will present our recent progress concerning a novel approach that allows to combine the factorization property of the NW limit and off-shell effects. Our approach is based on QCD factorization theorems for boosted top quarks in the resonance region and applies effective field theoretical methods known from SCET to the electroweak theory. The approach allows to incorporate resummed QCD corrections for differential top decay observables using boosted HQET generalizing results known from semileptonic $B$ decays in the endpoint region.
Speaker: Christoph Regner
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1
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16:00
Coffe break
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Talks: Afternoon session
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10
Deep Generative Models in Particle Physics
LHC run 3 has just started and in the years leading up to 2040, we will see a 20-fold increase in available data. This forthcoming dataset will have enormous potential for a deeper understanding of the Standard Model and possible physics beyond it. At the same time, the endless possibilities of new physics hiding in this dataset pose a challenge, both for our analyses and also our simulation algorithms.
In the past months, deep generative models (DGMs) like Midjourney, Dall-E, Stable Diffusion, or ChatGPT have attracted a lot of attention. Such models are not only able to generate images or text, but also help us in our understanding of the fundamental building blocks of nature. I will show how DGMs have become a standard tool in our numerical tool box, not only boosting the performance of existing algorithms, but also allowing for new analysis or simulation strategies. My talk not only considers the use of DGMs, but also addresses questions on how to control and evaluate such models against the precision requirements we have at the LHC.Speaker: Dr Claudius Krause (HEPHY Vienna (ÖAW)) -
11
Symplectic Singularities in Physics: Their Origins and Significance
Symplectic singularities, also known as hyper-Kahler singularities, encompass well-known geometric spaces such as the Kleinian surface singularities or the moduli space of instantons. Recently, a new class of symplectic singularities has emerged through the construction based on a physics model known as the 3d N=4 Coulomb branch.
In this presentation, I aim to provide an introduction and overview of symplectic singularities in general, with a particular focus on the 3d N=4 Coulomb branches. I will place special emphasis on the symplectic singularities that manifest as moduli spaces of vacua within supersymmetric field theories containing 8 supercharges in space-time dimensions ranging from 3 to 6. These instances showcase how geometric features offer elegant descriptions of strongly coupled phenomena.Speaker: Marcus Sperling (University of Vienna) -
12
Holographic Odderon at TOTEM?
In the Regge limit, diffractive $pp$ and $p\bar p$ scattering at large $\sqrt{s}$ is dominated by the Pomeron, with a smaller admixture from the Odderon, a tower of C-odd soft gluons. The Odderon is believed to be the C-odd partner of the C-even Pomeron. While the latter in its soft version dominates the diffractive $pp$ cross section at high energy, the manifestation of the former is still being debated, although recent results from the TOTEM collaboration have claimed it. In this talk I will present a holographic bottom-up model that captures all the necessary features required for Regge theory, and try to answer the question whether the currently available data supports the claimed discovery of the Odderon in the context of holography.
Speaker: Florian Hechenberger (TU Wien) -
13
Identified particle analysis with ALICE at the LHC
A long-standing topic in high-energy physics is how matter behaves in regimes of very high energy density. While ordinarily quarks and gluons are confined to hadrons, it is expected that, given sufficiently large energy densities, a deconfined state of matter called the Quark-Gluon Plasma (QGP) is formed. Conditions for the QGP to be formed can be achieved in the laboratory when heavy nuclei collide at ultra-relativistic speeds in accelerators such as the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), and signatures of QGP formation have been measured systematically over the past decades. In this talk, I will discuss the importance of identified particle observables and will elaborate on the next generation of measurements to be performed during the LHC Run 3 with the ALICE Experiment.
Speaker: David Dobrigkeit Chinellato (Austrian Academy of Sciences (AT)) -
14
Addressing the Initial Stages in heavy-ion collisions using jet quenching
Relativistic heavy-ion collision experiments are used to investigate the high-temperature properties of the strong interaction at large particle colliders (LHC, RHIC). In particular, they allow us to probe the non-equilibrium properties of the Quark-Gluon Plasma (QGP) created therein. Experimental evidence points towards a fast thermalization of this medium, but the initial stages before thermalization are still associated with large experimental and theoretical uncertainties. Experimentally accessible probes are jets, a large number of collimated highly energetic hadrons measured in the detectors. These jets stem from a very energetic quark or gluon created in the initial collision and are therefore sensitive to all stages of the QGP evolution. When traversing the QGP medium, they radiate soft gluons and deposit energy, typically modeled by the dependence on only a single medium parameter, the jet quenching parameter $\hat q$. In this talk, I will describe how we extracted this parameter during the initial stages using QCD kinetic theory and obtain its evolution throughout the whole collision process.
Based on arXiv:2303.12595, arXiv:2312.0047 and arXiv:2312.11252
Speaker: Florian Lindenbauer (TU Wien) -
15
Neutron puzzles: New perspectives
The pressing tension between different experimental results and theory predictions of neutron properties, such as the lifetime, is taken as motivation to revisit both, experimental uncertainties and novel theoretical hypothesis.
Speaker: Benjamin Koch -
16
Ultracold Neutrons beyond Newton: Remarks on next-to-leading order effects
In the recent years, ultracold neutrons have been used to explore the quantum nature of the gravitational interaction, like in the qBounce experiment. From a theoretical perspective, starting from Dirac equation in a curved spacetime, one can derive the non-relativistic Schr\"odinger equation that governs the evolution of the neutron's wave function in the Earth's gravitional field. This result has been obtained many times in literature, and at the lowest order it simply reproduce a Schrodinger system affected by a Newtonian potential. In this paper, we argue that, when going one step further in the perturbative expansion, one should be very careful, since terms that seems negligible at first glance, end up being of the same order of the other perturbative corrections to the neutron energy spectrum. Nevertheless, the current experiments' precision do not allow to probe for this corrections yet. Finally, we observe that, even if these contributions are negligible for the case of ultracold neutrons in Earth's gravity at the moment, they could still be relevant in other circumstances.
Speaker: alessandro santoni -
17
Free neutron decay experiment PERC
The Neutron and Quantum Physics Group at TU Wien pursues various research approaches in the field of particles and cosmology. In this talk, I will present a new neutron decay facility PERC; a precise determination of the weak axial vector coupling gA from a measurement of the b-asymmetry in the decay of free neutrons and the relationship to the unitarity of the CKM matrix. New symmetry tests of various kinds are coming within reach with the neutron decay facility PERC at Munich research reactor FRM2 or at ESS, the European Spallation Source.
Speaker: Alberto José Saavedra García (Technische Universität Wien - Atominstitut) - 18
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10
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19:05
Dinner
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12:30
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Talks: Morning session
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19
COSINUS and CRESST status update
The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) and COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiments are state-of-the-art initiatives in the field of dark matter direct detection research. Operating at millikelvin temperatures, both experiments employ a two-channel readout system utilizing transition edge sensors (TESs), allowing for effective particle discrimination. CRESST employs cryogenic detectors to search for WIMPs in the sub-GeV mass range, aiming to uncover the elusive nature of dark matter. On the other hand, COSINUS utilizes ultrapure NaI detectors to independently verify the DAMA/LIBRA dark matter signal. Both experiments, conducted at the Laboratori Nazionali del Gran Sasso in Italy, contribute crucial insights in the global pursuit of understanding dark matter's unknown properties.This talk will provide insights into the latest results, updates on ongoing efforts, and perspectives for the future.
Speaker: Mariano Cababie (Institut für Hochenergiephysik der Österreichischen Akademie der Wissenschaften) -
20
Coherent elastic neutrino-nucleus scattering and the NUCLEUS experiment
The coherent elastic neutrino-nucleus scattering (CEvNS) is a unique process to study neutrino properties and to search for new physics beyond the Standard Model, from Weinberg angle at low momentum transfer to sterile neutrinos. The NUCLEUS Collaboration aims to detect the coherent elastic scattering of neutrinos on nuclei using reactor (anti)neutrinos, in the fully coherent regime - no other experiment succeeded yet to measure CEvNS with reactor (anti)neutrino. This talk will review the physics potential of CEvNS and will present the status of the NUCLEUS experiment and its synergy with the dark matter research program at HEPHY.
Speaker: Dr Vasile Mihai Ghete (Austrian Academy of Sciences (AT)) -
21
Calibration of ~100 eV Nuclear Recoil with the CRAB Method
The aim of the CRAB method is to calibrate the response of low-background and very low threshold bolometric crystals, with direct impact on the study of coherent elastic neutrino-nucleus scattering and dark matter searches. It consists of a neutron capture on a nucleus of the crystal followed by a gamma-deexcitation, producing a nuclear recoil with a well-known energy. This provides a Thus calibration peaks associated to various isotopes of the target can be induced in the spectrum of nuclear recoils.
After presenting the principle of the CRAB method and its first experimental validations with CaWO4 crystals, we will discuss the underlying rich program of physics accessible by more accurate measurements, crossing particule, nuclear and solid state physics. The implementation of such accurate measurements in the coming year at the Atominstitut in Vienna is discussed in another talk.Speaker: Romain Martin -
22
Scattering of Dark Pions in an Sp(4) gauge theory
We consider strongly interacting dark matter candidates as composite states of Nf=2 fermions charged under a dark Sp(4) gauge group in the fundamental representation. We give expressions that allow the calculation of correlation functions of two pseudo-Nambu-Goldstone-bosons with lattice field theory and present first results on the scattering phase shift in the isospin-2 channel in the theory from first principles. We give a lower limit on the dark matter particle mass by comparing our results with astrophysical constraints on the cross-section.
Speaker: Yannick Dengler -
23
SIMPle thoughtsSpeaker: Josef Pradler (University of Vienna & Austrian Academy of Sciences (AT))
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24
CPT and Lorentz invariance tests by hydrogen and deuterium hyperfine spectroscopy and implications for ASACUSA's antihydrogen programme
Hyperfine structure measurements on antihydrogen can provide sensitive tests of CPT invariance. The ASACUSA collaboration proposed such a measurement on a beam of antihydrogen at the antiproton decelerator of CERN. Supporting matter experiments are of high relevance in antihydrogen research to benchmark spectroscopy equipment and methods. In addition, dedicated measurements on hydrogen and deuterium can put new or improved constraints on coefficients of the so-called standard model extension even without comparison to antihydrogen.
We have constructed an atom beam setup for Rabi spectroscopy and performed such measurements for hydrogen at CERN and for deuterium at the Laboratoire Aimé Cotton, Université Paris-Saclay. The analyses of which have been concluded recently and we can give a preview on the results we are about to publish. Finally, the relevance for antihydrogen spectroscopy will be discussed.Speaker: Martin Simon (Austrian Academy of Sciences (AT))
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19
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10:45
Coffe break
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Talks: Morning session
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25
R-matrix calculations for Nuclear Data Evaluation with GECCCOS
A new versatile module to perform R-matrix based multi-channel reaction calculations within GECCCOS (GEneral Coupled-Channel COde System) has been developed by the nuclear data group at TU-Wien especially for light nuclear systems. At present light nuclear systems bear challenges for nuclear data evaluation, especially at low energies. The sharp resonances in cross sections at low energies can only be described in a phenomenological way via R-matrix theory by fitting the corresponding resonance parameters to reproduce available experimental data. These R-matrix analyses of experimental data yield consistent reaction cross sections. However, the predictive power as well as the physics interpretation of these analyses are limited.
The GECCCOS R-matrix module aims to provide a development platform for reaction calculations within light nuclear systems to create new methods or improve and extend existing ones. Conventional methods as potential based computational R-matrix calculations using the Lagrange Mesh technique were implemented as well as the phenomenological R-matrix analyses of reaction data. In addition it is used as a development platform for non-standard extensions of R-matrix theory such as Reduced R-matrix theory and the Hybrid R-matrix.
After a successful calculation the complete S-matrix (collision matrix) as well as observables for unpolarized beams, angle-differential cross sections, excitation functions and, if existing, angle-integrated cross sections are returned. In case of phenomenological R-matrix analyses a separate module automatically assembles calculated and available experimental data, performs necessary conversions of units and frames of reference and calculates chi2 values for a fitting process.
This contribution aims to give a brief insight into current code developments of the nuclear data group at TU-Wien as well as present challenges regarding the description of reactions in light nuclear systems.Speaker: Thomas Srdinko -
26
Towards TMDs with contour deformations
Hadrons are strongly interacting particles composed of quarks and gluons and described by Quantum Chromodynamics (QCD). Their internal structure can be described in terms of structure functions that encode, for example, the momentum and spin distributions of their constituents. Parton distribution functions (PDFs) and Transverse Momentum Distributions (TMDs), for example, describe the quark and gluon momentum distributions inside a hadron. These distribution functions are, however, not easy to calculate, because they are defined on the light front, whereas most hadron calculations are performed in a Euclidean metric. The main problem is then to go from Euclidean onto the light front.
We are developing a new method to compute the parton distributions (TMDs and PDFs) from hadronic matrix elements needed contour deformations, which we illustrate for a simple system of two interacting scalar particles of equal mass, using an handbag approximation to the matrix element, that includes the two-body Bethe-Salpeter amplitude as input (calculated from its Bethe-Salpeter Equation). Afterwards, the projection onto the light front is done through a combination of contour deformations and analytic continuation methods. We then explore ways of extending the handbag approximation by adding "quark-quark" interactions via the introduction of the four-point function in the diagram, which, in turn, is calculated self-consistently, from its own scattering equation.
Speaker: Eduardo Ferreira -
27
NuPECC status and long range planSpeaker: Eberhard Widmann (Austrian Academy of Sciences (AT))
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28
General discussionSpeakers: Florian Reindl (Vienna University of Technology (AT)), Massimiliano Procura (University of Vienna (AT))
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25
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13:00
Lunch
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