Exotic Hadron Spectroscopy 2026

30 Mar 2026, 09:00 → 1 Apr 2026, 12:30 Europe/London

Centre for Mathematical Sciences, University of Cambridge

The workshop, to be held at the Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, brings together the nuclear and particle physics communities to discuss the latest developments (experimental and theoretical) in exotic and conventional hadron spectroscopy.

The spectrum of hadrons has become increasingly rich in recent years, owing to ongoing experimental discoveries at both particle and nuclear physics experiments. The properties of known states have been measured with improved precision, and many new states (both conventional and exotic) have been discovered. Often similar states and search methods are discussed separately in the particle and nuclear physics communities, with little interaction between them. This workshop facilitates communication between these communities, with the ultimate aim of improving our understanding of the spectrum of hadrons. A particular focus is new analysis methods and search strategies for current and future experimental facilities (CERN, JLab, Mainz, BESIII, BelleII, PANDA).

This is the sixth in a series of workshops on this topic, following previous events:

•    2016, University of Edinburgh
•    2017, University of Edinburgh
•    2019, University of York
•    2023, IPPP, Durham University 
•    2024, Swansea University

Thanks to financial support from the IPPP, the IoP HEPP and NP Groups and UKLFT, there is no registration fee and we expect to be able to provide tea/coffee breaks and lunches at no cost to participants. We also hope to have a workshop dinner (to be confirmed).

We expect to have a limited amount of funding to support early-stage researchers. This can be used to cover costs associated with accommodation or travel. If you want to apply for this funding, please email the organisers (exotichadrons@jiscmail.ac.uk) after you have registered with: your CV, details of your current position, and a brief summary (1 paragraph) of why you would like to attend and how you would contribute to the workshop. Full consideration will be given to those who apply by 1st February 2026.

The deadline for abstracts is 1st February 2026 and the deadline for registration is 26th February 2026.

Information about travel and accommodation can be found on this page. Please note that several participants have received phishing messages offering to book accommodation. We have not sent such messages and participants need to make their own accommodation arrangements.

Organising Committee: Bryan McKinnon (Glasgow), Christopher Thomas (Cambridge), Dan Watts (York), David Wilson (Cambridge), Mark Whitehead (Glasgow), Mikhail Bashkanov (York), Muhammad Naeem Anwar (Swansea), Timothy Burns (Swansea)

Sponsors: UKRI-STFC,  IPPP Durham University, IoP HEPP Group, IoP NP Group, Virtual Centre for UK Lattice Field Theory (UKLFT)

       

     

WorkshopPhoto.jpg

Monday 30 March

09:00 → 09:15 Registration

09:15 → 11:00 Talks

Convener: Christopher Thomas (University of Cambridge)

09:15 Welcome

Speaker: Christopher Thomas (University of Cambridge)

ExoticHadrons_Welcome.pdf

09:30 Latest results from Belle II on exotic hadron spectroscopy

The Belle and Belle II experiments have collected a 1.6 ab sample of e+
e- collision data at centre-of-mass energies near the Y(nS) resonances.
This provides a unique opportunity to study conventional and exotic
hadrons that cannot be described by the standard q\bar{q} or qqq
valence quark configurations.
In this talk, we present recent studies of exotic hadrons from Belle
and Belle II experiments. In particular, we show recent results and
prospects from Belle II concerning the properties of Υ⁡(10753), which
might be interpreted as exotic. In addition, we present evidence for an
excess of events near the mass of a charmed pentaquark state
𝑃𝑐⁢𝑠⁢(4459)0
and search for pentaquark states in Υ⁡(1,2⁢𝑆) inclusive decays, both
at Belle.

Speaker: Umberto Tamponi

tamponi_exotic_hadrons_cambridge_2026.pdf

10:00 Recent Advances in the Study of Charmonium-like States at BESIII

The BESIII experiment, operating in the τ-charm energy region, has conducted extensive studies of exotic hadronic states using the world’s largest data samples of electron-positron collisions at center-of-mass energies from 4.0 to 4.95 GeV. These studies systematically probe candidates beyond the conventional quark model, such as multiquark or hybrid configurations, by analyzing a diverse set of final states with high precision. Key results include stringent constraints on the decay properties of the prototypical exotic state X(3872), precise measurements of the cross-sections of electron-positron annihilation into hidden- or open-charm final states, detailed investigations of near-threshold states, and partial wave analyses involving the charged charmonium-like $Z_c$ states. With the upgraded luminosity and energy scan capabilities of BEPCII, these studies are poised to significantly advance our understanding of non-perturbative QCD and the spectrum of exotic matter in the charm sector. An overview of recent results and an outlook on future possibilities will be presented.

Speaker: Weimin Song (Jilin University College of Physics (CN))

besiii.pdf

10:30 Bayesian Inference as Discovery

Traditional methods of fitting data involves hypothesis testing, with "discovery" declared if the null hypothesis is rejected. This approach often assumes that the data is generated by the model, under-estimates systematic errors, and leads to overfitting. Common methods for overcoming the last issue, such as LASSO, AIC, and BIC do not perform well. In addition, the entire methodology relies on the dubious prospect of finding the global minimum of a complex multidimensional objective function. I propose to address these issues by reframing discovery as "predictiveness" -- namely does a postulated effect (eg, a new particle) assist in predicting new measurements. The method obviates many of the traditional problems and leads to more robust results. The implementation of the scheme and applications to simple problems will be presented.

Speaker: Eric Swanson

SwansonCambridge.pdf

11:00 → 11:30 Tea/coffee break

11:30 → 13:00 Talks

Convener: David Wilson (University of Cambridge)

11:30 Predicting three-hadron amplitudes from first-principles QCD

I will review recent advances in studying three-particle interactions directly from lattice QCD. By employing mathematical relations that connect finite-volume energies and matrix elements to physical scattering and decay amplitudes, it is now possible to calculate observables that go beyond the single-hadron regime. While the application to two-particle channels is well established, three-hadron amplitudes represents the current frontier. In addition to outlining the key formalism, I will highlight recent theoretical developments (e.g. for D D pi and N pi pi amplitudes) as well as recent applications (e.g. rho pi to pi pi pi scattering with a rigorously resonant rho). I will also discuss future prospects and open challenges.

Speaker: Max Hansen

Exotic-Hansen.pdf

12:00 Understanding isospin violation in the $X(3872)$ through molecular isotriplet mixing

Since its observation in 2003, the $X(3872)$ has stood out as one of the most puzzling exotic states in QCD, displaying properties that continue to challenge standard theoretical interpretations. In this presentation, I will address a particularly striking aspect of this state: the sizable isospin violation exhibited in its decays to $J/\psi\rho^0$ and $J/\psi\omega$. Despite being predominantly an isosinglet, the $X(3872)$ decays into these two final states with comparable branching fractions, of order $\mathcal{O}(1)$. I will show that this pattern can be understood in a simple and natural way by postulating the existence of a neutral isotriplet partner, $X_T^0$, and allowing for mixing between the two states through $D^0\bar{D}^{0}$ and $D^+\bar{D}^{-}$ meson loops. To reconcile this scenario with the absence of experimental signals for charged isotriplet partners, we assume that the isotriplet states have a molecular structure. While this makes them difficult to observe directly, their effects remain visible through their role in isospin-violating decay processes. In the molecular hypothesis, the couplings of the $X_T^0$ to the $DD^*$ channels and to $J/\psi\rho^0$ are not free parameters, but are instead linked to the binding energy of the molecular state. The resulting prediction for the ratio of isospin-conserving to isospin-violating decay modes is found to be fully consistent with the latest experimental data.

Speaker: Davide Germani (Sapienza Università di Roma & Istituto Nazionale di Fisica Nucleare)

Davide Germani isospin violation.pdf

Davide Germani isospin violation.pptx

12:30 Probing the spectroscopy and electromagnetic structure of light and heavy mesons within the light-front quark model

The inner structure of hadrons nowadays remains elusive due to both experimental limitations and the complexity of analytical approaches. In this talk, I would like to share my previous research work about the spectroscopy and hadron structure, especially in light and heavy mesons in the light-front quark model (LFQM). Starting from heavy mesons, where mass spectra, decay constant, and M1 radiative transition are computed by considering the QCD-effective Hamiltonian such as screening effect and the harmonic oscillator basis as the trial wave function in the $1S$ - $3S$. As for light mesons, with similar parameters, M1 radiative transition as well as distribution amplitude are quite interested to explore due to the nature of the chiral symmetry breaking. These results show good agreement with both experimental data and other theoretical predictions.

Speaker: Muhammad Ridwan (University of Plymouth)

Ridwan_slides_(2).pdf

13:00 → 14:00 Lunch

14:00 → 15:30 Talks

Convener: Mark Peter Whitehead (University of Glasgow (GB))

14:00 Latest results on exotic spectroscopy from LHCb

Exotic hadrons and precision studies of their properties offer important constraints on models of hadron structure and strong-interaction dynamics. In recent years a large number of exotic states have been discovered and studied by the LHCb experiment at CERN. This talk presents a summary of the latest results in the field of exotic hadron spectroscopy from LHCb.

Speaker: Aleksandrina Docheva (University of Glasgow (GB))

lhcb_exotic_spectroscopy_29_03_26.pdf

14:30 Electromagnetic form factors and structure of the $T_{bb}$ tetraquark from lattice QCD

We present the first lattice QCD determination of the electromagnetic form factors of the exotic tetraquark $T_{bb} \ (bb \bar u \bar d)$ with quantum numbers $I( J^P ) = 0( 1^+ )$. The extracted form factors encode information about its internal structure, including the charge distribution and the magnetic dipole moments, determined separately for the light and heavy quarks. Our results provide evidence in favor of it being a bound state consisting of a compact heavy diquark $[bb]$ in a color-antitriplet with spin one, and a light antidiquark $[\bar u \bar d]$ in a color-triplet with spin zero. The charge radius of $T_{bb}$ is found to be significantly smaller than the combined charge radii of $B$ and $B^*$ mesons. These two comprise the lowest-lying threshold $BB^*$ in the channel we are considering, and their electric charge form factors are also determined. The computations were performed on a single CLS ensemble with $N_f = 2+1$ dynamical quarks and a lattice spacing of approximately $a \approx0.064 \ \mathrm{fm}$ at the pion mass $m_\pi \approx 290 \ \mathrm{MeV}$.

Speaker: Ivan Vujmilovic

vujmilovic_exotichadrons.pdf

15:00 Application of chiral EFT to near-threshold exotics from finite-volume energy levels

Chiral effective field theory (EFT) provides a natural framework to explore the properties of near-threshold exotics with reliable error estimates at both physical and unphysical pion masses, and to connect these regimes via chiral extrapolations once the low-energy constants are fixed. We present a chiral EFT approach for extracting two-body scattering information from finite-volume energy levels obtained in lattice QCD. This framework allows for an explicit incorporation of long-range physics governed by one-pion exchange (OPE) and a model-independent treatment of coupled channels, serving as an alternative to Lüscher's method. We apply the chiral EFT approach to coupled-channel $B^{(*)}\bar D^{(*)}$ scattering to analyse the recent lattice QCD results by Alexandrou et al. [Phys. Rev. Lett. 132, 151902 (2024)] and obtain shallow bound states in both channels, in agreement with the lattice findings [arXiv:2602.02176]. The finite-volume spectra and extracted pole positions show a near-degeneracy in $J=0$ and $J=1$ channels, consistent with heavy-quark spin symmetry (HQSS). Using HQSS, we predict additional shallow bound states near the $B \bar D^*$ and $B^* \bar D^*$ thresholds, which are accessible to future lattice simulations. The corresponding effective range parameters support a molecular interpretation of the $T_{bc}$ state. In contrast to our findings in similar studies of the $T_{cc}^+$, the effect of OPE on the finite volume-spectra is found to be small for $T_{bc}$, with only moderate impact on HQSS partners.

Speaker: Michael Abolnikov (Ruhr University Bochum)

HadSpec26_talk_Abolnikov.pdf

15:30 → 16:00 Tea/coffee break

16:00 → 17:00 Talks

Convener: Mikhail Bashkanov

16:00 H-Dibaryon Search near the Lambda Lambda Threshold using a Kaon Beam

This presentation will provide an overview of experimental efforts to search for the H-dibaryon, focusing on the most recent findings from the J-PARC E42 experiment. The E42 experiment explores the existence of the H-dibaryon near the $\Lambda\Lambda$ and $\Xi^-p$ mass thresholds, having collected thousands of $\Lambda\Lambda$ production events through $(K^-, K^+)$ reactions on a $^{12}$C target at 1.8 GeV$/c$. Additionally, the talk will address the significance of the H-dibaryon in exotic baryon spectroscopy and its implications for advancing our understanding of multiquark states.

Speaker: Jung Keun ‍Ahn

2026ExoticBaryonSpectroscopy_JungKeunAhn_upload.pdf

16:30 The H-dibaryon at $m_\pi \simeq 200~\mathrm{MeV}$ from lattice QCD

We present a preliminary lattice QCD study of the H-dibaryon at a close-to-physical pion mass through the spectroscopic analysis of the strangeness $S=-2$, iso-singlet baryon-baryon system on the CLS D200 ensemble. This ensemble is at $m_\pi \simeq 200~\mathrm{MeV}$ and $m_K \simeq 480~\mathrm{MeV}$, using a $64^3 \times 128$ lattice with spacing $a \simeq 0.065~\mathrm{fm}$ and open boundary conditions in the temporal direction.

In this study, we determined the finite-volume spectrum using a GEVP on the $\Lambda\Lambda$, $N\Xi$, and $\Sigma\Sigma$ channels. Based on these results, a preliminary multi-channel Lüscher analysis of the extracted energy levels was performed. Firstly, with simple parametrisations of the inverse $K$ matrix, with the aim of extending the analysis to more flexible models. Particular attention is paid to left-hand cuts arising from one-particle exchanges, entering at $t=m_{\pi}^2$ in the $N\Xi$ and $\Sigma\Sigma$ channels in the relevant energy region.

Speaker: Juan Antonio Fernandez de la Garza (Universität Bern (AEC + ITP))

H_dibaryon_Exotic_Hadrons_2026_v3.pdf

19:00 → 22:00 Workshop dinner

Tuesday 31 March

09:30 → 10:30 Talks

Convener: Muhammad Naeem Anwar (Department of Physics, Swansea University)

09:30 BOEFT for XYZ state

We will present a QCD derived effective field theory description based on
scales separation and symmetries and show how this description can reproduce and predict the properties of the XYZ as well give us an understand of their nature.

Speaker: Nora Brambilla

Brambillacambridge2026.pdf

10:00 Measurement of exclusive J/$\psi$ photo-production with the CLAS12 experiment: unpolarized cross section and perspectives for polarization observables

The photo-production of vector mesons off the nucleon has long been established as an important tool to access the gluon content of the nucleon. In particular, the photo-production of J/$\psi$ near the threshold energy has been related to the Gluons Gravitational Form Factors of the nucleon. However, the validity of this interpretation must be tested and additional contributions such as open charm loop diagrams or possible pentaquarks have to be fully understood. In this talk, I will present results on the unpolarized cross-section of the near-threshold photoproduction of J/$\psi$, using data taken by the CLAS12 detector at Jefferson Lab, on proton and deuterium targets. Perspectives to measure beam and target polarization observables will also be discussed.

Speaker: Pierre Chatagnon (CEA Saclay)

ExHaSpec26.pdf

10:30 → 11:00 Tea/coffee break

11:00 → 12:30 Talks

Convener: Mikhail Bashkanov

11:00 Elucidating Strangeness with Electromagnetic Probes

Currently, there are only six cascade states (out of 44 predicted) that have at least a three-star rating in the PDG, with the production mechanism of these states still remaining mostly elusive. Cascade studies are promising as a tool to differentiate genuine quark states from hadronic molecules, since we have the ability to measure the line shape in various decay branches with unprecedented precision. Because we have ss in the final state, the number of diquark configurations we can have is constrained. As a doubly strange final state, it also gives us access to various exotic channels which might be viable for analysis.

This work focuses on the analysis of CLAS12 data collected at Jefferson Lab to study the production mechanisms and decays of excited cascade baryon states that are not well established or missing, with the aim of determining
their branching ratios and quantum numbers. Additionally, the possibility of exploring doubly strange exotics, an analogue of double charm exotics recently observed at LHCb, in the same dataset will be discussed.

Speaker: Aslı Acar

ExoticHadrons 3.pdf

11:30 Quark mass dependence of exotic resonances

In this talk I will discuss the quark mass dependence of several exotic
resonance states. On the one hand, I will talk about the exotic charmed mesons, the light and heavy pion mass dependence, and discuss about the effect of the possible mechanisms of attraction. On the other hand, I will discuss two-pole structures, and, in particular, I will review a recent work of analysis of LQCD data related to the Lambda(1405) in the baryon sector, where the quark mass dependence was extracted as the pole positions in the SU(3) limit.

Speaker: Raquel Molina Peralta

quarkmassexohad.pdf

12:00 Negative parity strange baryons in meson-baryon scattering

We present a lattice QCD investigation of baryon resonances with strangeness, focusing on their possible exotic nature, associated with their dynamical origin in meson–baryon interactions. In particular, the $\Lambda(1405)$ and its long-standing two-pole structure are studied, as well as the poorly understood $\Xi(1620)$ and $\Xi(1690)$. We discuss published coupled-channel results for the $\Lambda(1405)$ obtained at $m_{\pi}\approx 200$ MeV, together with preliminary finite-volume spectra from an additional ensemble at heavier pion mass. The analysis employs temporal correlation functions constructed from both single- and multi-hadron interpolating operators, enabling access to the meson-baryon components of these states. Using the Lüscher formalism, we have extracted scattering amplitudes for one ensemble in the $\Lambda(1405)$ sector, which suggest a virtual bound state below the $\pi\Sigma$ threshold and a resonance pole near the $\bar{K}N$ threshold, in qualitative agreement with phenomenological approaches.

Speaker: Barbara Alexandra Cid Mora (GSI Helmholtzzentrum für Schwerionenforschung)

ExoticHad-CidMora.pdf

12:30 → 13:30 Lunch

13:30 → 15:00 Talks

Convener: Dan Watts

13:30 Recent results from CMS on exotic hadron spectroscopy

The CMS experiment reports the observation of three structures in the J/ψJ/ψ→μ+μ−μ+μ− channel—X(6600), X(6900), X(7100)—each with a statistical significance well above 5σ, confirming and extending earlier Run 2 results. Strong interference effects among these states, also exceeding 5σ, indicate that they share the same quantum numbers. A complementary search in the J/ψ ψ(2S) channel reveals two structures consistent with the X(6900) and X(7100) resonances. A spin–parity analysis favors a JPC=2++ assignment, a rare quantum number among known hadrons. Taken together, these findings strongly support the interpretation of these states as a family of all-charm tetraquarks, offering new insights into the dynamics of exotic resonances. The ATLAS experiment has also studied the J/ψ ψ(2S) decay mode, including ψ(2S)→J/ψπ+π− with J/ψ→μ+μ−. In this analysis, the X(6900) state is observed with a significance above 5σ, while the X(7100) state is not confirmed. The latter was previously reported at the 3σ level in an earlier ATLAS search based solely on ψ(2S)→μ+μ− decays.

Speaker: Yilin Zhou (Fudan University (CN))

20260331ExoHad2026_YilinZhou.pdf

14:00 Tcc tetraquark in SU(3)-flavour-symmetric QCD

An ongoing study of the $T_{cc}$(3875) tetraquark using lattice QCD with degenerate up, down, and strange quarks with a pion mass of roughly 420 MeV will be presented. A comprehensive set of nine ensembles with six different lattice spacings allows full control over lattice systematics and a continuum extrapolation at this unphysical point. I will discuss the challenges in obtaining the correct finite-volume spectrum and the challenges in analyzing the spectrum taking into account the longest-distance part of the $DD^*$ interaction due to pion exchange.

Speaker: Jeremy Green (DESY, Zeuthen)

slides.pdf

14:30 Hypernuclei measurements with the ALICE experiment

Hypernuclei, bound states of nucleons and hyperons, offer a unique probe of the strong interaction with strangeness and provide key constraints on hyperon–nucleon interactions. The ALICE experiment at the CERN Large Hadron Collider, exploiting excellent particle identification at low transverse momentum and precise secondary-vertex reconstruction, has performed systematic measurements of light hypernuclei production in pp, p–Pb, and Pb–Pb collisions. In this contribution, the latest ALICE results on hypernuclei production and properties are presented, together with prospects for extending these studies in future LHC runs.

Speaker: Zhengqing Wang (Fudan University (CN))

Hypernuclei measurements with the ALICE experiment.pdf

15:00 → 15:30 Tea/coffee break

15:30 → 17:00 Talks

Convener: Timothy Burns

15:30 Meson and glueball spectroscopy with improved hadron creation operators

We investigate meson-glueball mixing on the lattice by means of improved interpolating operators. On the meson side, we extend the Hadron Spectrum Collaboration's derivative-based basis with optimal distillation profiles, resulting in a clearer resolution of the spectrum. On the glueball side, we build operators using the chromo-magnetic field and its gauge-covariant derivatives which couple strongly to states with fixed continuum $J^{PC}$, making them a better-conditioned basis compared to spatial Wilson loops generally used in lattice glueball studies. We map the low-lying scalar iso-vector and iso-scalar spectrum in a simulation with 2 degenerate quarks at $m_{\pi} \approx 2.2$ GeV using these meson and glueball operators, as well as quantify how these operators couple to the energy eigenstates to understand the composition of these states.

Speaker: Juan Andres Urrea Nino (Trinity College Dublin)

Exotic2026-Urrea.pdf

16:00 How can femtoscopy help in understanding exotic hadrons

Since 2003, many hadrons that do not fit into the conventional quark model of qqbar mesons and qqq baryons have been discovered experimentally. Because most (if not all) of these states are located at the thresholds of a pair of conventional hadrons, they have been conjectured to be hadronic molecules. There have been extensive theoretical and experimental studies to verify or refute the molecular picture from different perspectives. In the past few years, we have proposed using femtoscopy to directly extract the underlying hadron-hadron interactions, which are key for forming hadronic molecules. In this talk, I will provide a pedagogical introduction to femtoscopy and its recent applications in understanding the nature of a few key candidates for hadronic molecules, such as Ds0*(2317), Pc(4457/4440), and Zc(3900)/Zcs(3985).

Speaker: Li-Sheng Geng (Beihang University)

20260331-Geng.pdf

16:30 Time for discussion

18:00 → 19:00 Public talk

Wednesday 1 April

09:30 → 10:30 Talks

Convener: Timothy Burns

09:30 Dalitz-plot decomposition of $e^+ e^- \to J/\psi \pi \pi (K\bar{K})$ process in the 4.13-4.36 GeV range employing dispersive analysis

We analyse the processes $e^+ e^- \to \gamma^* \to J/\psi \pi \pi (K \bar{K})$ and $e^+ e^- \to \gamma^* \to h_c \pi \pi$ using the recently proposed Dalitz-plot decomposition approach, based on the helicity formalism for three-body decays. Within a Lagrangian-based toy model, we validate key aspects of this approach, namely the factorisation of the overall rotation for all decay chains and spin alignments, as well as crossing symmetry between final states. In analysing the experimental data, we describe the subchannel dynamics through a dispersive treatment of $\pi\pi/K\bar{K}$ interactions, reproducing the $f_0(500)$ and $f_0(980)$ pole structures. Using the latest $e^+ e^- \to J/\psi \pi \pi (K \bar{K})$ data in the 4.1271-4.3583 GeV range, we reproduce invariant mass spectra that reveal both $Z_c(3900)$ and $Z_c(4020)$ states and discuss prospects for further constraints on the $Y(4220)$ and $Y(4320)$.

Ermolina, Danilkin, Vanderhaeghen (Phys.Lett.B 864 (2025) 139450)
Ermolina, Danilkin, Vanderhaeghen (in preparation)

Speaker: Viktoriia Ermolina (Johannes Gutenberg University of Mainz)

EHS VE 01.04.pdf

10:00 Recent results from GlueX

The spectrum of hadronic states holds valuable information about the interaction of the strong force. Photoproduction experiments can provide crucial insights due to their ability to produce a wide range of conventional and non-conventional hadrons, such as exotic hybrid mesons with gluonic degrees of freedom.
The GlueX experiment at Jefferson Lab, VA, USA, features a 9 GeV linearly polarized photon beam, incident on a fixed LH2 target. A hermetic detector system with excellent charged and neutral particle identification capabilities surrounds the interaction region and provides coverage for charged and neutral final states. This makes GlueX well suited to study the light meson and baryon spectrum.
This talk will present recent results from GlueX.

Speaker: Peter Hurck (University of Glasgow (GB))

talk_PH.pdf

10:30 → 11:00 Tea/coffee break

11:00 → 12:30 Talks

Convener: Christopher Thomas (University of Cambridge)

11:00 Exploring Photoproduced $\eta^{(}{'^{)}} \pi$ Systems in the Search for Exotic Hadrons at GlueX

Mapping the light meson spectrum in the strongly coupled regime of QCD requires disentangling overlapping resonant and non-resonant contributions in multi-body final states, especially in channels where exotic quantum numbers may appear. This presentation highlights the ongoing amplitude studies of the lightest spin-exotic hybrid candidate, the $\pi_1$, in photoproduced $\eta\pi$ and $\eta'\pi$ systems using high-statistics data from the GlueX experiment at Jefferson Lab. With its linearly polarized photon beam and near-complete charged and neutral final-state coverage, GlueX enables amplitude analyses that exploit polarization, including separation by exchange naturality, to provide additional constraints on the production amplitudes and improve their sensitivity to potential underlying exotic contributions.

Speaker: Zachary Baldwin (Carnegie Mellon University)

11:30 Lattice QCD study of string breaking by light and strange quarks

We study using lattice QCD the phenomenon of string breaking, the flattening of the ground state potential between a static quark and a static anti-quark at large separation distance due to the formation of a pair of static-light mesons. We compute the three lowest energy levels of the static potential in QCD with light (degenerate up and down) and strange dynamical quarks for a set of quark masses and extrapolate to the physical point. We resolve the avoided level crossings due to string breaking. These energy levels can be used as input to investigations of quarkonia above threshold and heavy-light and heavy-strange coupled-channel meson scattering.

Speaker: Francesco Giacomo Knechtli (Bergische Universitaet Wuppertal (DE))

exohad-knechtli.pdf

12:00 Closing

ExoticHadrons_Closing.pdf