Excited QCD 2026 Workshop

Jan 8, 2026, 8:30 AM → Jan 14, 2026, 7:30 PM Europe/Madrid

University of Granada, Carmen de la Victoria

María Gómez-Rocha (Universidad de Granada)

 

This is a five-day workshop with time for winter sports in the Sierra Nevada mountain or historic sightseeing in Granada. 

The workshop will take placce at Carmen de la Victoria.

Attendance is limited to about 50 participants given the size of the conference room which we will be using.

For those going to ski, the meeting point can be found here.

November 3rd 2025:  The attendance limit is now being reached. Overbooking registrations will be routed to the conference chair to see what is possible. We apologize for the inconvenience, but EQCD will also take place in 2027, you may want to attend the next edition.

Organizing committee: 

• Maria Gómez Rocha (chair, Univ. of Granada)
• Pedro de A. Bicudo (Instituto Superior Técnico, Lisbon)
• Juan J. Gálvez Viruet (Univ. Complutense of Madrid)
• Roman Höllwieser (Universität Wien)
• Felipe J. Llanes Estrada (Univ. Complutense of Madrid)
• Alexandre Salas Bernárdez (Univ. Complutense of Madrid)
• Pablo Sánchez Puertas (Univ. of Granada)

Advisory committee:

• Francesco Giovanni Celiberto (Univ. de Alcalá, Madrid)
• Robert Kaminski (Institute of Nuclear Physics, Polish Academy of Sciences) 
• Jelena Jovicevic (KTH Royal Institute of Technology, Stockholm and Institute of Physics Belgrade)
• Marina Krstic Marinkovic (ETH Zurich)
• Raquel Molina Peralta (Institut de Fisica Corpuscular, Univ. de Valencia)
• Alessandro Pilloni (Istituto Nazionale di Fisica Nucleare and Univ. degli Studi di Messina)
• Jorge Segovia (Univ. Pablo de Olavide, Sevilla)

 

Hosted by the Univ. of Granada, coorganized with the IPARCOS Institute at Madrid's Complutense     

                                          

Thu, January 8

10:00 AM → 7:30 PM Arrival Day

7:30 PM → 8:00 PM Registration and welcome

8:00 PM → 9:00 PM Dinner should be included at your residence if you are opting for the university service

Fri, January 9

8:30 AM → 9:00 AM Registration and welcome

8:45 AM Welcome

Speakers: María Gómez-Rocha (Universidad de Granada), Pedro Bicudo (CeFEMA, IST, U. Lisboa)

Excited QCD intro.pdf

9:00 AM → 10:30 AM Talks

9:00 AM Effective field theory of composite nucleons in high density matter

At sufficiently high baryon densities, such as those found in compact star cores, the internal quark-gluon wave functions of neighboring nucleons begin to overlap and delocalize, hinting at a percolation-like transition. Modeling such systems is particularly challenging, as nucleons gradually lose their identities and can no longer be treated as appropriate degrees of freedom. In this talk, I will discuss an effective field theory (EFT) that incorporates the internal structure of nucleons through modified nucleon field operators. Rather than employing complex many-quark composite field operators, this EFT retains nucleon fields whose anticommutation relations deviate only slightly from the canonical fermionic form. These deviations, arising from the internal structure of nucleons, are explicitly dependent on the baryon density. I will also present numerical results for the equation of state of both symmetric nuclear matter and pure neutron matter, obtained within the mean-field approximation of this EFT framework.

Speaker: Gastao Krein (Instituto de Física Teórica, Universidade Estadual Paulista)

1_Krein.pdf

9:30 AM Compatibility of LQCD predictions for the $T_{cc}(3875)^+$ with experiment and a comparative study with the $X_{c1}(3872)$

Recent Lattice QCD (LQCD) simulations have confirmed an attractive interaction in the isoscalar $DD^*$ channel, which is naturally associated with the $T_{cc}(3875)^+$ state observed by LHCb in the $D^0D^0\pi^+$ spectrum. However, the connection between the virtual bound state predicted by LQCD and the experimental signal remains an open question. In this talk, we present an Effective Field Theory (EFT) analysis of LQCD data, showing that a consistent chiral extrapolation leads to a $T_{cc}$ pole compatible with experiment. Additionally, we explore the light and heavy quark mass dependence of the $T_{cc}$ pole and discuss the role of $\rho$ and $\pi$ meson exchanges.

Furthermore, we extend our study to include a comparative analysis between the $T_{cc}(3875)^+$ and the $\chi_{c1}(3872)$, investigating possible universal behaviors and differences in their quark mass dependence. This combined approach provides deeper insights into the nature of near-threshold exotic hadrons and their relation to LQCD predictions.

Speaker: Fernando Gil Domínguez (UESTC)

FGD Granada.pdf

10:00 AM Hadronic form factors in QCD and the incompleteness problem in the time-like region

Hadronic form factors are around since Hofstadter proved the finite proton size in 1955 in electron scattering experiments, identified as matrix elements of the em current. Since then, the nucleon and other hadronic form factors have been measured or computed in lattice QCD using all sorts of currents: electromagnetic, axial or gravitational. In the time-like region analyticity, chiral perturbation theory and perturbative QCD play a key role and imply a set of normalization and superconvergent sum rules which are rigorous conditions. We show several instances where these conditions are flagrantly violated due to a lack of information in the region above the largest known resonances and the below the onset of pQCD. We popose to use radial Regge trajectories to fill the gap and examine the consequences.

Speaker: Prof. Enrique Ruiz Arriola (Universidad de Granada, Spain)

RuizArriola_Excited_QCD-2026.pdf

10:30 AM → 11:00 AM Coffe break

11:00 AM → 12:00 PM Talks

11:00 AM Efficiently simulating quarkonium's evolution beyond the dipole approximation

The open quantum system framework allows one to compute quarkonium's evolution in a medium, keeping track of the needed quantum features. However, computing this evolution is a computationally demanding task. QTRAJ is an efficient code that allows one to simulate the behavior of quarkonium in a medium in the case in which the medium sees quarkonium as a small color dipole $rT\ll 1$. While this limit is accurate for $\Upsilon(1S)$, its applicability to other quarkonium states is unclear. In this talk, wwe present a generalization of this code that incorporates the regime where $rT \sim 1$ in the one-gluon exchange approximation. In its new version, QTRAJ implements new jump operators connecting different states, which are then expanded in plane waves, giving rise to a variation of the algorithm present in QTRAJ 1.0 where jumps with $\Delta \ell > 1$ are allowed. We will show a review of this approach comparing the $rT\ll 1$ and $rT\sim 1$ cases, and we present preliminary phenomenological results.

Speaker: Miguel Ángel Escobedo Espinosa (Universitat de Barcelona)

4_Escobedo.pdf

11:30 AM Overview of PHENIX experiment at RHIC

The Relativistic Heavy Ion Collider (RHIC) has been in operation since 2001, contributing significantly to the study of strong interactions described with QCD, and nuclear matter under extreme conditions. The PHENIX experiment, operated from 2001 to 2016, has collected a comprehensive dataset and continues to publish scientific papers to yield impactful results from initial to final stages of nucleus collisions.

These measurements have provided critical insights into the properties of the quark-gluon plasma (QGP), cold nuclear matter (CNM) effects also in small collision systems, and the structure and dynamics of quarks and gluons within polarized protons. And there have been systematic measurements of the EM probes (direct photons), Jets (or high pT hadrons), and heavy flavor probes. The direct photon yields showed interesting dN/dy dependence from the small systems to the large systems. The identified particle productions would shed light on particle production in both soft and hard sectors, which would cross-check and understand results primarily coming from hard and EM processes.

In this presentation, identified charged-hadron invariant pT and mT spectra, nuclear-modification factors and particle ratios, in p + Al, 3He +Au, and Cu + Au collisions at sqrt(s_NN) = 200 GeV and in U+U collisions at sqrt(s_NN) = 193 GeV measured by PHENIX are shown. And the physics interpretations including collective flow aspects for those measurement are presented. The values of freeze-out temperatures and average collective velocities have been obtained. It should also be noted that v2 flow values and pi0 productions in those various collision systems, have been measured by the PHENIX. The direct photon enhancement in various collision systems are also discussed. These findings highlight the ongoing contributions of PHENIX experiment at RHIC to advancing our understanding of strong interactions described with QCD and the nuclear matter.

Speaker: Sato Susumu (JAEA)

0101_2026_ExcitedQCD2026_Phenix_v009.pdf

12:00 PM → 12:30 PM Bus

12:30 PM → 6:00 PM Ski/Monuments and Lunch

Sat, January 10

9:00 AM → 10:30 AM Talks

9:00 AM Obtaining bounds on the cold nuclear matter equation of state while evading the sign problem

QCD Euclidean space path integrals of have a sign problem when a chemical potential is included; this inhibits our ability to calculate the equation of state (EOS) of nuclear matter. This sign problem goes away if the if the chemical potential is imaginary. Unfortunately imaginary chemical potentials are not physical; traditionally they have been used as the starting point for an analytic continuation to real chemical potentials, but this method fails at low temperatures. This talk proposes a novel way to get upper and lower bounds on the EOS of cold matter $\epsilon(n)$ (where $\epsilon$ is the energy density and $n$ is the baryon number density) directly from calculations using imaginary chemical potentials. The method exploits special relativity and the fact that calculations of the partional function for an imaginary chemical potentials are equivalent to caculations with real Lagrange multipliers enforcing a baryon current density rather than number density.

Speaker: Thomas Cohen (University of Maryland)

1_Cohen.pdf

9:30 AM Three-body decays with Khuri-Treiman equations

One of the main issues posed by the presence of hadrons in any reaction is their final-state interactions, which are formally expressed in terms of the unitarity of the amplitude. In two-body scattering, unitarity is usually imposed in the direct channel only, as one is not sensitive to the details of the crossed channels. This is certainly not the case for a three-body decay, where the three possible two-hadron channels are physical, and one ideally wants to impose unitarity in all channels at once. The Khuri-Treiman formalism is a dispersive approach which indeed allows one to do so. In this talk, I will review the contributions made by the JPAC Collaboration to this field with focus on various important applications, e.g. $V\to3\pi$ $(V=\omega,\phi,J/\psi)$ or the exotic $\pi_{1}(1600)\to3\pi$ decay.

Speaker: Sergi Gonzalez-Solis (Universitat de Barcelona)

ExcitedQCD26_Sergi.pdf

10:00 AM A precision test of First Row CKM Unitarity from Lattice QCD

Current precision tests of the Standard Model show a deficit in the first row unitarity of the CKM matrix. At the current level of precision, the only relevant CKM matrix elements that contribute to first row unitarity are $V_{ud}$ and $V_{us}$. Without resorting on nuclear inputs, they can be extracted from the combination of the experimental decay width of kaon and pion leptonic decays along with the theoretical calculation of their decay constants, combined with the decay width of semileptonic kaon decays with the computation of the corresponding form factor at zero momentum transfer. In this talk we will discuss progress towards a correlated analysis of the lattice inputs needed for this test using highly improved staggered quarks (HISQ) on the MILC $N_f=2+1+1$ configurations along with Staggered Chiral Perturbation Theory (SChPT) as a functional form for the chiral-continuum limit.

Speaker: Ramón Merino Rojas (Universidad de Granada)

RamonExcitedQCD.pdf

10:30 AM → 11:00 AM Coffe break

11:00 AM → 1:00 PM Talks

11:00 AM Heavy quark thermodynamics with anisotropic lattices

We present recent results from the FASTSUM collaboration, using anisotropic lattice QCD to study spectral properties of heavy quarkonia and open heavy flavour systems at high temperature. For heavy quarkonium, our results using a number of different suggest a small but significant and robust negative mass shift as well as an increasing thermal width. We present the first lattice results for masses and spectral functions of B mesons at high temperature, and preliminary results for a high-precision calculation of the static quark potential.

Speaker: Jon-Ivar Skullerud (Maynooth University)

HeavyQuarks.pdf

11:30 AM Heavy QCD bound states at Belle and Belle II

The Belle and Belle II experiments have collected a 1.6 ab$^{-1}$ sample of $e^+e^-$ collision data at centre-of-mass energies near the $\Upsilon(nS)$ resonances. This provides a unique opportunity to study conventional hadronic states, such as charmed meson and baryons, charmonium and bottomonium. However, it also opens a window to the study of exotic hadron states, such as tetraquarks, pentaquarks, glueballs, hybrid states, etc.

In this talk, we provide a review of recent results obtained with the Belle and Belle II datasets.

Speaker: Christoph Schwanda (Marietta Blau Institute for Particle Physics)

eqcd2026_schwanda.pdf

12:00 PM Kaon-deuteron correlation function from an effective field theory approach

We consider kaon-deuteron femtoscopy correlation functions using elementary kaon–nucleon scattering amplitudes within unitarized chiral effective field theory. The amplitudes are obtained through the impulse approximation, accounting for single kaon–nucleon scatterings, and through the fixed-center approximation to the Faddeev equations, which includes multiple re-scattering effects. The resulting correlation functions are highly sensitive to source size and relative momentum, showing strong deviations from the Coulomb baseline driven by the presence of the $\Lambda (1405)$ resonance below threshold and inelastic channels. Our calculations agree well with ALICE data, demonstrating the potential of femtoscopy in probing strange hadronic interactions.

https://arxiv.org/abs/2507.22593

Speaker: Dr Juan Torres-Rincon (Universitat de Barcelona)

EQCD2026_TorresRincon.pdf

12:30 PM Charmonium(-like) states production at LHCb

Charmonium production measurements are powerful tests of QCD. The models of charmonium production separate the quark pair production, well understood, and the hadronisation, which is non perturbative. The most successful model so far, non-relativistic QCD, requires input from experimental results to constrain the non-perturbative component. With its precise vertex reconstruction, powerful charged hadron identification and a flexible trigger, the LHCb experiment at the LHC is well-suited for charmonium measurements. In this talk, a summary of recent charmonium(-like) states production measurements will be given, including prompt and non-prompt measurement, associated production and production in $p Pb$ collisions.

Speaker: Raoul Henderson (Université Paris-Saclay)

Excited_QCD_Granada_2026_pres.pdf

Henderson.pdf

1:00 PM → 3:00 PM Lunch

3:00 PM → 4:30 PM Talks

3:00 PM Precise dispersive description of pion-pion interactions and model-independent determination of resonances

A precise description of low-energy pion-pion interactions is essential for many problems in hadronic physics. We present new global fits that satisfy dispersive constraints within uncertainties up to 1.6 GeV, while describing all available experimental data up to 1.8 GeV. Using continued-fraction expansions, we extract resonance pole parameters in a model-independent way from forward dispersion relations.

Speaker: Pablo Rabán Mondéjar (Universidad Complutense de Madrid)

Raban_ExcitedQCD2026.pdf

3:30 PM Jet propagation in the Glasma phase in a Light-Front Hamiltonian formalism

We study the momentum broadening of a high energy quark jet in the high-density gluon medium created right after the collision of two ultrarrelativistic heavy nuclei, the Glasma. Previous Glasma studies consider the jet as a classical probe particle, for which position and momentum are simultaneously determined. In this talk, we use the light-front QCD Hamiltonian formalism [1,2] to treat the jet as a fully quantum state and compute its real-time evolution while propagating through the Glasma classical background fields, that appear as an interaction potential in the quantum evolution of the jet. We present results for the momentum broadening experienced by a jet at mid-rapidity, paying special attention to the anisotropies in the momentum broadening between the longitudinal and transverse directions with respect to the collision axis. We also carry out an analysis of the differences between the canonical momentum, conjugated to the position in the Lagrangian and the kinetic momentum which corresponds to the physical observable. For all our results we perform a comparison with the classical calculations that have been carried out so far [3].

[1] M. Li, X. Zhao, P. Maris, G. Chen, Y. Li, K. Tuchin, J. P. Vary, Ultrarelativistic quark-nucleus scattering in a light-front Hamiltonian approach. Phys. Rev. D 101, 076016 (2020). https://doi.org/10.1103/PhysRevD.101.076016

[2] M. Li, T. Lappi, X. Zhao, Scattering and gluon emission in a color field: A light-
front Hamiltonian approach. Phys. Rev. D 104, 056014 (2021). https://doi.org/10.1103/PhysRevD.104.056014

[3] . Ipp, D.I. Müller, D. Schuh, Jet momentum broadening in the 2 + 1D Glasma: Analytic weak field approximation and lattice simulations. Phys. Rev. D 102, 074001 (2020). https://doi.org/10.1103/PhysRevD.102.074001

Speaker: Carlos Lamas Rodriguez (IGFAE-USC)

Slides_Granada_v2.pdf

4:00 PM An improved unitarization method and a search for molecular-type hidden charm pentaquarks

The existence of the nucleonic pentaquark resonances $P_{c\bar{c}}(4312)^+$, $P_{c\bar{c}}(4380)^+$, $P_{c\bar{c}}(4440)^+$, $P_{c\bar{c}}(4457)^+$, $P_{c\bar{c}s}(4338)^0$ and $P_{c\bar{c}s}(4459)^0$, established by the LHCb collaboration, has been one of the major discoveries in hadron physics in the latest years. Most of these states (5 out of 6) can be understood as meson-baryon bound states.

By unitarizing the scattering amplitude in the $t$-channel vector-meson exchange interaction model one can investigate the dynamically generated resonances. In the recent works [1,2] we revisited the procedure of the unitarized coupled-channel hidden gauge formalism, which has been a very successful approach in explaining many exotic hadrons in the charm and hidden charm sectors. Employing realistic regularization parameters, we predicted two double strangeness pentaquarks of molecular nature.

Now we go one step further and propose an improved unitarization method. The unitarization procedure requires the regularization of the meson-baryon loop function, commonly done using either a cut-off ($G^{\text{CO}}$) or dimensional regularization ($G^{\text{DR}}$). Although both schemes should yield similar results, some unphysical structures in the T-matrix were found that could not be associated to any resonance or bound state. Now we introduce a novel hybrid loop function ($G^{\text{HY}}$), which combines both dimensional and cut-off regularizations. This approach avoids the generation of unphysical poles and, thus, enables a much cleaner analysis of the scattering amplitude. We shall show that with the use of hybrid loop function the basic properties of the dynamically generated states remain unaltered. Such an improved procedure allowed us to predict two new pentaquark states in the $S = -1$, $I = 1$ sector.

These recently predicted molecular-type pentaquarks (two in $S = -2$, $I = 1/2$ and two in $S = -1$, $I = 1$) are dynamically generated in a very specific way via a strong non-diagonal attraction between the two heaviest meson-baryon channels [1,2]. This effect was overlooked before, because other research groups were discouraged by the repulsive character of the diagonal kernel coefficients, and because the complex structure of the scattering amplitudes obtained with both $G^{\text{DR}}$ and $G^{\text{CO}}$, with unphysical structures, has obscured these physical states.

We hope that our work would stimulate experiments looking for these new pentaquark states, the discovery of which would enrich the family of observed exotic baryons.

References
[1]. J.A. Marsé-Valera, V.K. Magas and A. Ramos, Phys. Rev. Lett. 130 (2023) no.9, 9.
[2]. J.A. Marsé-Valera, V.K. Magas and A. Ramos, Phys. Rev. D 111 (2025) no.5, 5.

Speaker: Volodymyr Magas (Universidad de Barcelona)

Magas_Granada_2026.pdf

4:30 PM → 5:00 PM Coffe

5:00 PM → 6:30 PM Talks

5:00 PM Magnetically induced Kondo effect in QCD via the 3-flavor PNJL model

Various physical phenomena arise in QCD in the presence of strong magnetic fields. Some of them, such as magnetic catalysis and inverse magnetic catalysis, have already been well studied on the lattice, in QCD-like models, effective field theories, etc. Moreover, it has been proposed that an analog of the Kondo effect, which emerges in dense QCD, may also be present in magnetized QCD at zero density. This phenomenon is sometimes dubbed the Magnetically Induced Kondo Effect (MIKE). In this work, we study the properties of this effect in the 3-flavor Polyakov-Nambu-Jona-Lasinio (PNJL) model, as a toy model for QCD at finite temperature, with two mass-degenerate light quarks and one heavy quark. In particular, we search for the region in the phase diagram where this effect occurs. Our primary observable is the Kondo condensate, a flavor-non-singlet fermion bilinear involving a mixture of light- and heavy-quark fields. We investigate the temperature and magnetic-field dependence of the Kondo condensate and compare this quantity with the familiar chiral condensate. Finally, we discuss possible avenues to compute the Kondo condensate in lattice QCD.

Speaker: Adeilton Dean Marques Valois (University of Granada)

Excited_QCD_2026_deanvalois.pdf

5:30 PM The analytic structure of the QCD propagators, confinement, and deconfinement

Confinement and deconfinement of quarks and gluons can be understood in terms of the absence or presence of corresponding asymptotic states and/or quasi-particle-like excitations in the physical spectrum of QCD. In this talk, I will discuss our current knowledge of said spectrum, as encoded in the analytic structure of the QCD propagators, and I will report on recent results concerning the gluon spectrum at low and intermediate temperatures. I will then discuss the role non-perturbative contributions play in shaping the analytic structure of the QCD propagators, and possible developments in our understanding of confinement and deconfinement stemming from taking such contributions into account.

Speaker: Giorgio Comitini (Università degli Studi di Catania)

Analytic structure QCD propagators - ExcitedQCD 2026.pdf

Sun, January 11

9:00 AM → 10:30 AM Talks

9:00 AM Chiral-scale effective field theory for dense and thermal systems

The behavior of scale symmetry in dense and thermal systems is an interesting topic in nuclear physics as it relates to the stiffness of equation of state. In this talk, I will discuss the nuclear matter properties by using an effective field theory with respect to the trace anomaly of QCD---chiral scale effective field theory. Explicitly, the pseudoconformal structure, the behavior of sound velocity, and a new power counting scheme convenient for study the meson fluctuation effects.

Speaker: Yong-Liang MA

20260111_ChiralScale_Spain.pdf

20260111_ChiralScale_Spain.pptx

9:30 AM Hadro- and Photo-production of Exotic Mesons

I will present a theoretical and experimental overview of the production of eta-pi and eta’-pi with pion beam (COMPASS) and photon beam (GlueX).
These two-meson systems are known to have odd angular waves with exotic quantum numbers.
The JPAC collaboration has been analyzing the COMPASS and GlueX data in order to extract the properties of the lightest exotic meson, the pi_1(1600). In this talk, I will review the main features and present the plan for future work.
This talk will be based on the following publications:

A.~Jackura et al. [JPAC and COMPASS],
``New analysis of eta pi tensor resonances measured at the COMPASS experiment,'' Phys. Lett. B 779 (2018), 464-472

A.~Rodas et al. [JPAC],
``Determination of the pole position of the lightest hybrid meson candidate,''
Phys. Rev. Lett. 122 (2019) 042002

L.~Bibrzycki et al. [JPAC],
``pi^-p --> eta', pi^- p in the double-Regge region''
Eur. Phys. J. C 81 (2021), 647
[erratum: Eur. Phys. J. C 81 (2021) 915]

G.~Montaña et al.
``High-energy $η^{(\prime)}π$ photoproduction and the nature of exotic waves,''
preprint [arXiv:2510.14549 [hep-ph]].

Speaker: Vincent Mathieu (University of Barcelona)

ExcitedQCD.pptx

Mathieu.pdf

10:00 AM A continuum Schwinger method to study the pion’s generalized parton distribution

The formalism of Dyson-Schwinger equations is a powerful tool to study correlation functions in quantum field theory, but has also proved to yield an outstanding framework for the evaluation of hadron properties. Starting from state of the art continuum Schwinger calculations of pion's parton distribution function, we describe its extension to off-forward hadron kinematics, yielding the pion's generalized parton distribution. From that point on, we evaluate the amplitude for deeply virtual Compton scattering (DVCS) in the kinematic regime covered at the foreseen Electron-Ion Collider. Predictions for the event-rates and beam spin asymmetries to be observed are presented, revealing the dominance of gluon content within the pion in driving its response to DVCS at future electron-ion collider energies.

Speaker: Jorge Segovia (U. Pablo de Olavide, Seville)

Slides_CSMPionGPDs_JS.pdf

10:30 AM → 11:00 AM Coffe break

11:00 AM → 1:00 PM Talks

11:00 AM Chiral and U(1) axial restoration in Effective Field Theories

In this talk, I will report on recent results concerning chiral and U(1)_A restoration, both from an analysis based on Ward identities, which are formally derived from QCD, and from effective field theories, which are provided by U(3) chiral perturbation theory.
These results lead to relevant conclusions about the behavior of chiral partners (in terms of susceptibilities) in the limit of exact restoration and explain the current tension between Nf=2 and Nf=2+1 lattice simulations regarding U(1)_A restoration.

Speaker: Jacobo Ruiz de Elvira Carrascal (Complutense University of Madrid)

Ruiz-de-Elvira.pdf

11:30 AM Recent jet measurements with ALICE at the LHC

The ALICE experiment at the LHC is focused on the investigation of the Quark-Gluon Plasma (QGP), a fundamental state of matter at high temperature in which quarks and gluons are deconfined, and which is generated in heavy-ion collisions at ultra-relativistic energies. One of the key experimental signatures to explore the structure and dynamics of the QGP is ‘jet quenching’, the modification of the jet structure resulting from the interaction of high-energy quarks and gluons with the plasma. In this talk I will discuss recent ALICE measurements of jet quenching which utilise excellent particle tracking down to low momentum in high-density environments. These capabilities enable jet-quenching measurements over a very broad phase space, including low-energy and large-radius jets that are seen to be strongly modified, providing a window into the response of the QGP to excitations. ALICE particle-identification capabilities also provide the unique opportunity to use jet hadrochemistry as a differential probe of jet-medium interactions at the LHC.

Speaker: Prof. Marielle Chartier (University of Liverpool)

Marielle Chartier ExQCD26.pdf

12:00 PM Femptoscopy correlation functions applied to hadron phenomenology

We present recent theoretical advances in the study of femtoscopic correlation functions (CFs) as tools to probe hadron interactions and the nature of hadronic resonances. We show the relation between femtoscopy and invariant mass distributions, and discuss modified both Koonin-Pratt and Lednicky-Lyuboshits formalisms. We also present the incorporation of Coulomb interactions into CF calculations through a practical formalism combining strong and electromagnetic potentials, avoiding the numerical solution of Schrodinger equation, and allowing a direct comparison with Effective Field Theory amplitudes. We will also show some recent results and predictions in meson-meson and meson-baryon femtoscopy.

Speaker: Miguel Albaladejo Serrano (IFIC (CSIC & UV))

Albaladejo_eQCD2026_finalcompilation(1).pdf

12:30 PM Pions reloaded

In a recent work, a novel approach to the physics of mesons has been put forth, which permits one to go beyond the traditional rainbow-ladder approach in a symmetry-preserving way. In this talk we review the salient features of the framework, and show in detail its applicability for the physics of massless pions.

Speaker: Joannis Papavassiliou (Department of Theoretical Physics, University of Valencia)

Joannis-pions.pdf

1:00 PM → 3:00 PM Lunch

3:00 PM → 4:30 PM Talks

3:00 PM Quantum Simulations of QCD within a particle-based encoding

One of the most anticipated applications of quantum information science is the simulation of complex systems. Those involving quarks and gluons are particularly compelling, as their real-time phenomenology remains elusive to computational techniques such as traditional Monte Carlo methods. Overcoming these challenges could provide unprecedented insights into the dynamics of partons.

In this context, we discuss the calculation of fragmentation functions, key to describe how quarks and gluons transform into observable hadrons. As we move along we introduce a series of strategies to face the problem using quantum computers, all grounded in a codification paradigm where particles and their internal degrees of freedom are the central objects.

Speaker: Juan José Gálvez Viruet (Univ. Complutense de Madrid)

JJGV_110126.pdf

3:30 PM Advancing our understand of in-medium QCD splittings

In-medium parton splitting functions (PSFs) are a central ingredient in the description of the propagation of jets inside the quark-gluon plasma. Despite their critical importance, these objects have only been computed under a set of strong approximations concerning both the kinematics and the medium. In this talk, we present a novel approach so as to obtain the medium-induced modification factor on the PSFs for all QCD splittings channels in finite-$N_c$, with full kinematics and flexibility on the medium model. In our method, we formulate the problem as a set of time-evolution equations as done in [1], where we then employ advanced numerical methods (such as the Faber polynomial expansion of evolution operators [2]) in order to obtain fast, precise and stable results in all the phase space. This calculation goes significantly beyond the state-of-the-art by delivering the first complete leading-order calculation of the medium-induced spectrum. Furthermore, we assess the size of the corrections with respect to the usual approximations, where significant impacts are found both on the PSF description and on the observable level, such as the energy-energy correlators, which are also shown and confronted with experimental results.

[1] JHEP 09 (2023) 049
[2] arXiv:physics/0512074v1 [physics.comp-ph]

Speaker: Marco Leitão (IPhT - Saclay)

presentation.pdf

4:00 PM Antistatic-antistatic-light-light potentials and disentanglement of excited states

We report on our ongoing lattice QCD computation of antistatic-antistatic-light-light potentials using the CLS $N_f=2$ gauge configurations and the OpenQ*D codebase. We improve on previous work by calculating the correlation matrices for all three attractive ground state potentials previously characterized, to mitigate excited state contributions and further probe the vague indication of one-pion exchange at static quark separations $r\geq0.5$fm. Furthermore, we attempt to implement Wilson flow smearing at the source and sink, and we bolster our statistical analysis by taking into account autocorrelations using the pyerrors package.

Speaker: Bernardo Picão (Instituto Superior Técnico)

B_Picao_eQCD2026.pdf

4:30 PM → 5:00 PM Coffe

5:00 PM → 6:30 PM Talks

5:00 PM The role of thermal photons in a magnetized plasma and their significance in heavy ion collisions

Strong magnetic fields have a profound impact on the behavior of hot plasma, resulting in distinct correlations among charged particles in observed data. However, the corresponding theoretical prediction is complicated by a large uncertainty in the magnetic field. This presentation will delve into recent progress in deriving closed-form expressions for the one-loop photon polarization and photon emissions from hot magnetized plasma. Furthermore, we will discuss strategies derived from our theoretical insights that can assist in measuring magnetic fields in real-world physics applications, including heavy ion collisions.

Speaker: xinyang wang (Anhui University of Science & Technology)

Excited QCD 2026_Xinyang.pptx

5:30 PM Unquenched Radially Excited $P$-wave Charmonia

The ground-state positive-parity charmonia $\chi_{c0}(1P)$, $\chi_{c1}(1P)$, $h_c(1P)$, and $\chi_{c2}(1P)$ [1] are generally well described in static (``quenched'') quark models [2], in which dynamical effects of actual or virtual strong decay are neglected. Since these states lie below their lowest OZI-allowed decay thresholds of pairs of open-charm mesons, the resulting real, negative mass shifts can largely be accounted for by redefining the parameters of the confining interaction only, leaving e.g. the typical ratio $\left\{M({}^{3\!}P_2)-M({}^{3\!}P_1)\right\}/\!\left\{M({}^{3\!}P_1)-M({}^{3\!}P_0)\right\}$ almost unchanged [3].

In contrast, the five observed [1] candidates for $P$-wave charmonia around roughly 3.9 GeV, probably including the first radial excitations of the above ones, display a totally different pattern of masses. For instance, the $\chi_{c1}(3872)$ (formerly called $X(3872)$ [4]) is even lighter than the $\chi_{c0}(3915)$. Moreover, alongside the latter scalar meson, the additional $\chi_{c0}(3860)$ further complicates the picture. Note, however, that all these five charmonia have been seen to decay to one or more final states of two open-charm mesons, thus turning them into resonances of wildly varying widths, depending on the precise location of their lowest decay thresholds. The estimates of real mass splittings
given in Ref. [3] are no longer valid for these resonances, subject to complex mass shifts upon unquenching, owing to strong decay.

In this talk I shall present results for the first radial excitations of $P$-wave charmonia obtained with the Resonance-Spectrum Expansion [5], including all OZI-allowed decay channels of ground-state charm-meson pairs. Employing the generalised scheme of computing coupling constants for decays based on the ${}^{3\!}P_0$ model as developed in Ref. [6] ensures that no distortion of the spectra will occur due to the different classes of permitted decay channels for the various positive-parity charmonia.

[1] S. Navas et al. [Particle Data Group], Phys. Rev. D 110 (2024) 030001.
[2] S. Godfrey and N. Isgur, Phys. Rev. D 32 (1985) 189.
[3] T. J. Burns, Acta Phys. Polon. Supp. 8 (2015) 31 [arXiv:1411.2485].
[4] S. Coito, G. Rupp, and E. van Beveren, Eur. Phys. J. C 71 (2011) 1762 [arXiv:1008.5100]; 73 (2013) 2351 [arXiv:1212.0648]; M. Cardoso, G. Rupp, and E. van Beveren, Eur. Phys. J. C 75 (2015) 26 [arXiv:1411.1654].
[5] E. van Beveren and G. Rupp, Annals Phys. 324 (2009) 1620 [arXiv:0809.1149].
[6] E. van Beveren, Z. Phys. C 17 (1983) 135 [arXiv:hep-ph/0602248].

Speaker: George Rupp

Rupp.pdf

Mon, January 12

9:00 AM → 10:30 AM Talks

9:00 AM Bulk viscous dense quark matter

The transport properties of the high-density matter found in neutron stars affect the gravitational wave signals observed from colliding neutron stars. In particular, the effects of bulk viscosity differ from quark and nuclear matter. I will discuss the general hydrodynamic evolution of relativistic and dense matter near equilibrium. Focussing on the case of unpaired quark matter, I address how recent advances have made it possible to compute the equation of state with sufficient generality---at finite densities, temperatures, and with finite quark mass(es)---within perturbation theory. Lastly, I will display recent results showing how bulk viscous quark matter can be modelled as a two-component viscoelastic fluid, with one of the components dominating the dynamics depending on the temperature regime.

Speaker: Saga Aurora Säppi (Institute of Space Sciences (ICE-CSIC))

granada-v2.pdf

9:30 AM Exotic multistrange-anticharm baryon systems

We study exotic baryon systems composed of anticharmed mesons and strange baryons using the extended local hidden gauge approach. By solving the coupled-channel Bethe-Salpeter equation with interaction kernels from vector meson exchange, we explore the formation of hadronic molecular states in sectors with strangeness S = −1, −2, −3 and −4.
We systematically consider all possible isospin configurations and include both octet and decuplet baryons in the coupled-channel systems. Our results indicate that attractive interactions in S = −1, −2 can dynamically generate bound states, while systems with S = −3, −4 have repulsive interactions and do not support molecular formation. We also investigate vector-baryon systems with D¯ ∗ and D¯ ∗s mesons, finding similar but more deeply bound states. The results show that bound exotic states are more likely when one or two strange quarks are present. To assess the robustness of our predictions, we perform an uncertainty analysis by varying the cutoff parameter qmax, which affects the loop function regularization. The variations lead to moderate shifts in the pole positions, confirming the qualitative stability of the molecular states. These results highlight the strangeness dependence of the molecular formation mechanism and provide theoretical predictions
that can guide future experimental searches for exotic multistrange-anticharm baryon systems.

Based on the works

L.~Roca, J.~Song and E.~Oset,
``Molecular pentaquarks with hidden charm and double strangeness,''
Phys. Rev. D 109, 094005 (2024)

J.~Song and E.~Oset,
``Exotic multistrange-anticharm baryon systems,''
Phys. Rev. D 112, 074026 (2025)

Speaker: Eulogio Oset (IFIC, CSIC-University of Valencia)

hyp25.pdf

10:00 AM Electromagnetic properties of heavy-light mesons

Within the Bethe-Salpeter framework, we present a computation of space like electromagnetic form factors for pseudoscalar mesons, including light and heavy-light systems. Our approach employs a flavour-dependent variation of the standard Taylor effective charge, which contains key contributions from the quark-gluon vertices. This effective interaction is a common ingredient of all relevant dynamical equations, and accommodates the crucial mass differences between the various quark flavours. Particular attention is paid to the nonperturbative determination of the quark-photon vertex.

Speaker: Angel Miramontes (University of Valencia)

Miramontes_EQCD2026.pdf

10:30 AM → 11:00 AM Coffe break

11:00 AM → 12:00 PM Talks

11:00 AM Chirally and chiral spin symmetric hot matter in a model with manifest confinement

We present properties of the quark–antiquark mesons at zero and finite temperature in the framework of a solvable chirally symmetric quark model with an interquark linearly rising interaction where the string tension is the only model parameter. We demonstrate that while the confining interaction induces spontaneous breaking of chiral symmetry at T = 0, it gets restored at a chiral restoration temperature T_ch ​≃ 90 MeV. The physical mechanism responsible for chiral symmetry restoration in the confining regime is Pauli blocking of the quark levels, required for the existence of a nonvanishing quark condensate, by thermal excitations of the quarks and antiquarks. Thus, above T_ch, meson-like states are chirally symmetric and approximately chiral spin symmetric. A crucial property of the confined meson-like light-light states above T_ch​ is their size that exceeds drastically that in the chirally broken phase below T_ch​. Heavy-heavy mesons nearly preserve their size irrespective of the temperature. Furthermore, the root-mean-square radii of the states with J = 0 and J = 1 diverge in the chiral limit. This unexpected property must be a key to understanding unusual features of the hot QCD matter as observed at RHIC and LHC.

Speaker: Robert Wagenbrunn

wagenbrunn.pdf

11:30 AM New measurement of $K^{+} \rightarrow \pi^{+}\nu\bar{\nu}$ branching ratio at the NA62 experiment

The $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay is a golden mode for flavour physics. Its branching ratio is predicted with high precision by the Standard Model to be less than $10^{-10}$, and this decay mode is highly sensitive to indirect effects of new physics up to the highest mass scales. A new measurement of the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This new dataset was collected after modifications to the beamline and detectors and at a higher instantaneous beam intensity with respect to the previous 2016--2018 data taking. Using the NA62 datasets from 2016--2022, a new measurement of $\mathcal{B} (K^{+}\rightarrow\pi^{+}\nu\bar{\nu}) = \left(13.0^{+ 3.3}_{- 2.9} \right)\times 10^{-11} $ is reported, and for the first time the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay is observed with a significance exceeding $5\sigma$.

Speaker: Vlacheslav Duk (INFN)

duk_excited_qcd_12jan26_v2.pdf

12:00 PM → 12:30 PM Bus

12:30 PM → 6:00 PM Ski/Monuments and Lunch

8:30 PM → 10:30 PM Social Dinner

Tue, January 13

9:30 AM → 11:00 AM Talks

9:30 AM Neutron star structure and nuclear matter properties from a general Walecka-type models with Bayesian analysis

With the increasing richness of neutron star observations and ongoing experiments on nuclear structure, a fertile ground has emerged for exploring QCD across a wide range of densities. In our previous studies of nuclear matter properties based on a baryonic extended linear model—where the delta meson is included in the equation of state—we found that the resulting parameter space differs significantly from that of conventional Walecka-type models, in which interaction operators are often introduced for phenomenological convenience.

This discrepancy arises because the baryonic extended linear model incorporates vacuum physics, such as hadron masses generated via spontaneous chiral symmetry breaking, thereby maintaining a closer connection to QCD. In contrast, traditional approaches, particularly those focused on high-density regimes, typically neglect the underlying QCD symmetry patterns of the effective Lagrangian.

To deepen our understanding of the parameter space, we constructed a generalized Walecka-type Lagrangian that includes rho, omega, sigma, and delta mesons. All dimension-4 effective operators were systematically included without arbitrary selection. We then employed Bayesian analysis to constrain the parameter space using both neutron star observations and nuclear structure data.

Our study examined the interplay between interaction operators, nuclear matter properties, and neutron star characteristics. For example, we analyzed how the mass-radius (M-R) relation depends on key quantities such as incompressibility and the slope of the symmetry energy.

Speaker: Yao Ma (Nanjing University)

Representation-2026Spain.pdf

10:00 AM Scalar and vector-meson SU(3) degeneracy within unitarized Chiral Perturbation Theory

We use NLO unitarized SU(3) Chiral Perturbation Theory (ChPT) to generate the lightest scalar and vector resonances,
in terms of the ChPT renormalized low-energy constants, with no additional parameters. By varying the quark masses, we follow the poles associated with each of these resonances through different Riemann sheets
until we reach the SU(3) and chiral limits. In a regime, resonance poles in the contiguous sheet become degenerate for members of the same multiplet, and we identify them firmly as SU(3) multiplet members.
We also demonstrate that poles in other sheets are not degenerate, even in this limit.

Speaker: Jose Ramon Pelaez sagredo (Universidad Complutense de Madrid)

2026-01-13-ExcitedQCD2026-Granada-JRPelaez.pptx

10:30 AM Heavy and heavy-light tensor and axial-tensor mesons in the Covariant Spectator Theory

We present the first calculations of the masses of heavy and heavy–light tensor and axial-tensor mesons with total angular momentum up to J=3, obtained within the Covariant Spectator Theory (CST). This fully-relativistic Minkowski-space framework describes the quark–antiquark interaction through a covariant generalization of a one-gluon-exchange plus linear-confining potential. The CST formalism—previously applied successfully to heavy and heavy–light mesons with Jπ=0± and 1±—is here extended to arbitrary spin-parity Jπ. Our model involves a small set of parameters, determined from global fits to the measured spectra up to J=3. Our results provide a very good description of the existing experimental data and predict some yet unobserved states. These predictions may guide future experimental searches at facilities such as LHCb and Belle II. Furthermore, the model offers a systematic framework for analyzing the partial-wave compositions, and for assigning quantum numbers to still undetermined quark–antiquark states listed in the PDG. It also contributes to the identification of possible non–quark–antiquark configurations.

Speaker: Elmar Biernat (Instituto Superior Técnico, Universidade de Lisboa)

Biernat_eQCD_2026.pdf

11:00 AM → 11:30 AM Coffe break

11:30 AM → 1:00 PM Talks

11:30 AM Rho mesons and the compressibility of nuclear matter in the Skyrme model.

In this talk I will discuss some recent advances in an effective theory of QCD at low energies, where nuclei and baryons are described by topological soliton solutions known as Skyrmions.

Following the great success of coupling the rho mesons to the Skyrme field (which provided more realistic nuclear binding energies for the model and the triggering of nuclear clustering), we have recently shown the role that the leading $\rho \pi$ interaction term can play in the study of dense nuclear matter. This contribution, motivated by a theoretical construction from a Yang-Mills theory in one higher dimension, astonishingly reduces the compression modulus that the Skyrme model provides from the very large value of $K_0 ≃1080$ MeV to a more physical $K_0 ≃351$ MeV.

Speaker: Carlos Naya (Universidad de Alcalá)

CNaya-Granada-January2026.pdf

12:00 PM Tracing Baryon Number with Heavy Ion Collisions

In quantum chromodynamics (QCD), the baryon number is a conserved quantity. It is traditionally assumed to be evenly distributed among valence quarks in nucleus. However, an alternative framework proposes that this number is carried by a non-perturbative, Y-shaped topology of gluons connecting to three quarks. While neither hypothesis has been conclusively verified experimentally, new observations from the STAR Collaboration provide insights challenging the conventional valence quark picture.

In this talk, we will present STAR’s measurements from Ru+Ru and Zr+Zr collisions of the ratio of net baryon number (B) to the net charge difference (ΔQ = Q(Ru) − Q(Zr)) within mid-rapidity (|y| < 0.5), as well as net-proton yields from photonuclear Au+Au collisions as a function of rapidity. We find that the measured B/ΔQ far exceeds the expectation based on valence quarks. In addition, net-proton yields from photonuclear Au+Au collisions show weaker rapidity dependence than models without junction interactions. These results all favor the baryon junction hypothesis: since the junction composes of low-momentum gluons, it is easily stopped and results in enhanced baryon number being transported to mid-rapidity.
email: ctsang@bnl.gov

Speaker: Chun Yuen Tsang (BNL - On behalf of STAR colaboration)

ExcitedQCD_2026_v4.pdf

12:30 PM Understanding large localized CP violation in \boldmath{$B^\pm\to K^\pm\pi^+\pi^-$} using dispersive methods

We utilize the universality of pion--pion ($\pi\pi$) final-state interactions at small invariant masses to understand the enhanced local CP violation in $B^\pm\to K^\pm\pi^+\pi^-$, using a dispersive approach. From a fit to the integrated CP-asymmetry data, we successfully predict the Dalitz-plot kinematic distribution of the asymmetry in the low-energy $\pi\pi$ region, including the large local CP violation recently observed by LHCb. An essential role is played by the contributions of isospin 2. This formalism, whose parameters have a physical meaning, can be adapted straightforwardly to other systems with CP violation enhanced by final-state interactions.

Speaker: Ms Alba Reyes Torrecilla (Departamento de Física Teórica and IPARCOS, Universidad Complutense de Madrid)

ReyTorr_Alba_ExcitedQCD_2026.pdf

1:00 PM → 2:30 PM Lunch

2:00 PM → 4:40 PM Talks

2:30 PM Unveiling femtoscopic correlations of light hadrons

The ALICE collaboration has recently reported $\pi^+K_S$ and $K^+ K_S$ femtoscopic correlations. Here we demonstrate that the data can be well reproduced using realistic interactions, and provide predictions for other light-hadron channels. This approach leads to an accurate description of the $\kappa/K^0(700), \rho(770)$ and $a_0(980)$ resonances. Moreover, we propose a novel framework to interpret femtoscopy from the perspective of Chiral Perturbation Theo lory (ChPT).

Speaker: Alejandro Canoa Monsalve (Universidad Complutense de Madrid)

ExcitedQCD26_Canoa.pdf

3:00 PM Heavy-Flavor Fragmentation: The QCD Portal to Exotic Matter

We investigate the core dynamics behind exotic matter formation via the TQ4Q1.1 set of collinear, variable-flavor-number-scheme fragmentation functions for fully charmed or bottomed tetraquarks in three quantum configurations: scalar ($0^{++}$), axial vector ($1^{+-}$), and tensor ($2^{++}$). We adopt single-parton fragmentation at leading power and implement a nonrelativistic QCD factorization scheme tailored to tetraquark Fock-state configurations. Short-distance inputs at the initial scale are modeled using updated calculations for both gluon- and heavy-quark-initiated channels.vA threshold-consistent DGLAP evolution is then applied via HF-NRevo. We provide the first systematic treatment of uncertainties propagated from the color-composite long-distance matrix elements that govern the nonperturbative hadronization of tetraquarks. Our analysis represents a further step toward bridging the domains of hadronic structure, precision QCD, and exotic matter.

Speaker: Francesco Giovanni Celiberto (UAH Madrid)

talk_Excited_QCD_Celiberto_TQ4Q20.pdf

3:30 PM Bottom-up approach to describe groomed jet data in heavy-ion collisions

The theoretical interpretation of jet observables in heavy-ion collisions is a complex task due to the intricate interplay of perturbative and non-perturbative effects. One way to reduce this complexity is to groom away soft, wide-angle radiation so that perturbative dynamics dominates. Even in this simplified scenario, there are competing explanations for the physical origin of the measured medium-induced modifications.
We present a new approach to compute groomed sub-structure observables. The core idea is to treat medium effects as an effective energy shift of the hard, vacuum-like substructure. We first study a NLO-exact dijet configuration in vacuum and apply radiative energy-loss to the two subjets. The latter includes a gradual onset of colour decoherence depending on the opening angle of the two subjets. We find that this minimal setup already captures the narrowing trend of groomed observables but it’s not able to quantitatively describe the existing data. Next, we match the NLO matrix-element to a leading-logarithm accurate parton shower and perform a clustering algorithm to recover a two-prong system to which we again apply the energy-loss distribution. Despite its simplicity, the model results in a very good theory-to-data agreement (within 10%) for a broad range of observables including both ALICE and ATLAS kinematics.

Speaker: Mr Diogo Costa (FTAE - Universidad de Granada)

9_Costa.pdf

4:00 PM Phenomenological Insights from Dyson–Schwinger Equations: The $^3P_0$ Model and (Hybrid) Meson Decay

Dyson–Schwinger equations (DSEs) provide a non-perturbative framework for computing QCD Green’s functions. When constrained by lattice QCD data, these solutions—originally formulated in Euclidean space—can potentially be analytically continued to Minkowski space. Achieving this continuation enables the extraction of hadronic phenomenology directly from non-perturbative DSE calculations.

Meson decay models frequently invoke the creation of quark–antiquark pairs in a $^3P_0$ state —a scalar configuration that does not arise in perturbative QCD due to chiral symmetry. By employing DSEs constrained by lattice data for the quark propagator and quark–gluon vertex—naively extended into the Minkowski domain—we explore (in https://arxiv.org/abs/2312.14994) how such a scalar vertex may emerge dynamically in tandem with constituent quark mass generation.

Additionally, several established techniques will be discussed for reliably extending Euclidean DSE solutions to Minkowski space. These methods provide a foundation for extracting further phenomenological insights, particularly in the context of hybrid meson decays involving quark–antiquark–gluon (qqg) states, within a fully non-perturbative QCD framework.

Speaker: Dr Alexandre Salas-Bernárdez (Universidad Complutense de Madrid)

eQCDSalas-Bernardez.pdf

4:30 PM → 5:00 PM Coffe

5:00 PM → 6:30 PM Talks

5:00 PM Pion Weak Decay in a Magnetic Field

In this talk, I will discuss how the pattern of chiral symmetry breaking can be utilzied to compute vector and axial-vector pion matrix elements in a uniform magnetic field. The results are constructed within chiral perturbation theory and therefore model independent for a magnetic field, $\sqrt{eB}$, weaker the typical hadronic scale of $4\pi F_{\pi}\sim 1\ \rm{GeV}$. The matrix elements determine the decay rate of both charged and neutral pions. We also compared our results with lattice QCD for which there is some tension.

Speaker: Prabal Adhikari (Saint Olaf College)

PA-Pion Weak Decay.pdf

5:30 PM Machine learning unveils the quark mass dependence of the pseudoscalar meson decay constants in three-flavour NNLO ChPT

The quark mass dependence of the pseudoscalar meson decay consntants, $f_\pi, f_K$ and $f_\eta$, are determined from three-flavor ChPT till pion masses of around $750$ MeV, around the SU(3) limit. This is done by conducting an analysis of recent LQCD data using the LASSO method, a machine-learning technique which allows to pin down the relevant low-energy-constants with high precision. Since the pion decay constant is a fundamental quantity which usually appears in relevant phenomenological lagrangians or Effective Field Theories based on QCD at low energies, this analysis can be used as input to evaluate the quark mass dependence of hadronic states. As an example, we predict the masses of the octect baryons in the SU(3) limit within covariant Baryon Chiral Perturbation Theory.

Speaker: Zejian Zhuang (University of Valencia and IFIC)

ExciteQCD2026_zejian_zhuang.pdf

Wed, January 14

9:00 AM → 10:00 AM Talks: Discussion session (workshop conclusion, proceedings format).

10:00 AM → 7:30 PM Departure Day