840. Wilhelm and Else Heraeus Seminar on Real-Time and Non-Equilibrium Quantum Field Theory

31 Aug 2025, 08:45 → 5 Sept 2025, 23:00 Europe/Vienna

Oberwölz, Austria

Gernot Eichmann, Reinhard Alkofer, Markus Huber, Willibald Plessas (Institute of Physics, University of Graz), Dénes Sexty

Quantum Field Theory has proven to be a powerful tool in many areas of physics. In the last decades, advancements in QFT techniques, especially those beyond perturbation theory, have enabled significant progress in addressing questions related to the real-time and non-equilibrium dynamics of quantum fields. Nevertheless, substantial work remains to be done to fully grasp the fundamental aspects of these complex phenomena. Given their importance for many areas of physics such as astrophysics, cosmology, heavy-ion physics, and quantum simulators, it is essential to bring together experts who employ diverse methods to investigate the time evolution of quantum fields.

One prevalent approach to study the real-time behavior of (strongly) interacting quantum fields involves the analytic continuation of correlation functions determined in Euclidean space using various non-perturbative methods. Alternatively, Poincaré-covariant phase space formalisms, such as the Dirac-Heisenberg-Wigner formalism, offer a more direct method for understanding the time evolution of quantum fields far from equilibrium. Furthermore, recent advances in quantum computing have enabled direct calculations, thereby opening up fascinating possibilities for exploring QFT predictions in a wide range of non-equilibrium systems.

The aim of this meeting is to bring together leading experts and early-stage researchers working on these topics. The traditional Symposium in Oberwölz, taking place amidst the scenic Styrian Alps, provides the ideal setting for such a workshop. The critical comparison of different approaches and the diverse backgrounds of the participants will foster cross-fertilization among the various existing techniques in real-time and non-equilibrium quantum field theory, identify potential synergies, and decisively advance them further.

 

This event is supported by the Wilhelm and Else Heraeus Stiftung, the University of Graz, the City of Oberwölz and the Province of Styria.

 

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Programmheft Konzert ENGLISCH.pdf

Sunday 31 August

Registration

19:00 Dinner

Monday 1 September

Registration

Talks

Convener: Gernot Eichmann

1 Opening

Speaker: Gernot Eichmann

welcome.pdf

2 Quantum fields out-of-equilibrium, fluid dynamics and response theory

The dynamics of strongly interacting quantum fields can to a large extent be described with relativistic fluid dynamics. This is based on an expansion around thermal equilibrium states and their extension to local equilibrium. The connection between the fluid description and the underlying quantum field theoretic description can be formulated in terms of linear and non-linear response theory. I will review essential elements of this construction and discuss how it can be developed further.

Speaker: Stefan Floerchinger (University of Jena)

FloerchingerOberwölz2025 Stefan Floerchinger.pdf

10:30 Coffee break

Talks

Convener: Gernot Eichmann

3 Exploring exclusive proton-proton reactions with CBM at FAIR

The study of hadronic matter and its interactions is important for understanding Quantum Chromodynamics (QCD) in the context of hadron formation and structure. This talk will introduce briefly the physics program of the upcoming Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt in nucleus-nucleus collisions and focus on its hadron physics program. Here, the goal is to study hadron properties in proton-proton (pp) reactions with exclusively reconstructed final states.
Using the proton beams at energies up to 29 GeV ($\sqrt{s}$ = 7.6 GeV) delivered by the SIS100 accelerator of FAIR, and the CBM experiment, we aim to explore the production of multi-strange and charm baryons, and to search for exotic resonances over a wide energy range.
Preliminary feasibility studies on hadron production, spectroscopy, and hadron structure using exclusive final states in pp collisions with CBM will be presented.

Speaker: Shreya Roy (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))

SRoy_talk_Oberwolz2025-exclusive_pp_version_presented.pdf

4 QCD with an infrared fixed point and a dilaton

In a first part I will deduce scaling dimensions by matching
the chirally broken gauge theory to the pion effective theory.
Consistency with soft theorems, the lattice and N=1 supersymmetric gauge theories will be discussed.
In a second part, I will consider how the interpretation extends to include a dilaton, the Goldstone due to spontaneous scale symmetry breaking. Gravitational form factors offer a way to assess the sigma-meson as a dilaton and infrared conformality. I will confront these signatures with recent lattice data.

Speaker: Roman Zwicky (Edinburgh University)

25_Oberwoelz Roman Zwicky.pdf

12:30 Lunch break

Talks

Convener: Joannis Papavassiliou

5 Probing the Space-Time Structure of Parton Showers with the Quark-Gluon Plasma

Parton showers are a cornerstone of high-energy physics phenomenology, modelling how energetic quarks and gluons radiate and fragment into jets of hadrons. While traditionally formulated in momentum space, a space-time understanding of parton showers remains elusive, even though it is essential to probe the underlying dynamics of QCD in both perturbative and semi-perturbative regimes. In this talk, I will explore the emergent space-time picture of QCD radiation and how ultra-relativistic heavy-ion collisions provide a unique environment to test it.

The formation of a hot and dense QCD medium — the Quark-Gluon Plasma (QGP — in such collisions offers a rare opportunity: not only modifies jet evolution but also serves as a dynamical medium that encodes the temporal unfolding of the parton shower. By studying how jets interact with this evolving QCD medium, we gain access to the time ordering of emissions, the coherence properties of radiation, and the possible interplay between vacuum-like and medium-induced structures.

I will present a proof-of-principle study demonstrating that the space-time structure of parton showers has observable consequences, using a controlled toy Monte Carlo framework to isolate and quantify formation-time effects. Building on this, I introduce a novel reclustering technique—the τ-algorithm—that uses parton formation time as an ordering variable. This tool enables the dynamical selection of jets based on their in-medium propagation history, opening the way for time-resolved studies of jet-medium interactions and offering a new lever arm to connect jet observables with the evolving QCD background.

Speaker: Liliana Apolinario (LIP (PT))

LilianaApolinario.pdf

6 Simulating scattering amplitudes

The description of complex phenomena in large multiplicity final states of high energy collisions require a detailed understanding of scattering amplitudes with many external legs, and how such amplitudes are ultimately projected onto the asymptotic final states observed in experiments. I will introduce how we develop theoretical frameworks and simulation methods which go beyond the phenomenological reasoning and probabilistic algorithms underpinning the commonly used event generators, by introducing novel methods of simulating the evolution of density operators and scattering amplitudes for collider reactions and beyond.

Speaker: Dr Simon Plätzer (Universität Graz & Universität Wien)

slides-reduced.pdf

16:30 Coffee break

Talks

Convener: Joannis Papavassiliou

7 Progress in describing effective Interactions within the Hamiltonian formalism

We present results obtained in recent years using the renormalization group procedure for effective particles. An effective Hamiltonian is derived from the canonical QCD Hamiltonian and used to solve the corresponding renormalization group equation. Focusing on an effective theory involving only heavy quarks, we obtain an effective potential that resembles proposed phenomenological models and reproduces experimental spectra. A similar renormalization group method is applied to separate energy scales in pion–pion scattering processes. Several new computational tools are introduced: one for handling perturbative expansions via diagrammatic techniques, and another that enables the formulation of quark and gluon states on a quantum computer.

Speaker: Maria Gomez Rocha

Oberwoelz_2025 Maria Gomez Rocha.pdf

8 Temporal and spatial structures in the Sauter-Schwinger effect

M. Diez1, R. Alkofer1, and C. Kohlfürst2
1 Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
2 Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany

Pair creation in ultra-strong background fields, particularly the Sauter-Schwinger effect, has been a long-standing theoretical prediction. Despite extensive studies, one aspect, the formation times of particles, has remained elusive. In this poster, I present our recent work on time scales in Sauter-Schwinger pair production. To this end, we study the time evolution of observables in spatially and temporally structured electric fields within a (1+1)-dimensional Dirac-Heisenberg-Wigner approach. In order to interpret these extracted observables at intermediate times we use a hypothetical shutoff procedure [1]. The switching off of the field at intermediate times allows us to study pair and charge densities at non-asymptotic times. From this, we are able to identify different time scales in both, the spatial and momentum domains. We perform a detailed analysis of multiple parameters to obtain power laws for the parameter dependence of the time scales for pair production in the case of a single Sauter pulse [2,3]. This work therefore allows us interesting insights into non-equilibrium quantum systems.

References

[1] A. Ilderton, Phys. Rev. D 105, 016021 (2022)
[2] M.Diez, R.Alkofer, C.Kohlfürst, Phys. Lett. B 844, 138063 (2023)
[3] M.Diez, R.Alkofer, C.Kohlfürst, „Temporal and Spatial Scales in Particle production from Ultra-Strong Fields”, in preparation

Speaker: Matthias Diez (Universität Graz)

Diez Matthias.pdf

19:30 Reception dinner

Tuesday 2 September

Talks

Convener: Peter Lowdon

9 Kernels in complex Langevin simulations

Lattice simulations of real-time quantum field theory, as well as of various other systems, suffer from the infamous sign problem preventing the straightforward application of usual lattice approaches based on importance sampling. The complex Langevin method aims at bypassing the sign problem and is based on a stochastic evolution of complexified degrees of freedom in an artificial time dimension. However, the method is known to sometimes give incorrect results despite its apparent correct convergence. In this talk, I discuss possible origins of this wrong convergence as well as potential cures via the introduction of a so-called kernel into the complex Langevin equation.

Speaker: Michael Mandl (University of Graz)

mandl_handout.pdf

mandl_presentation.pdf

10 Machine Learning Kernels for Real-Time Complex Langevin

Real time evolution in QFT poses a severe sign problem, which may be alleviated via a complex Langevin approach.
However, so far simulation results consistently fail to converge with a large real-time extent. A kernel in a complex Langevin equation is known to influence the appearance of the boundary terms and integration cycles, and thus kernel choice can improve the range of real-time extents with correct results. For multi-dimensional models the optimal kernel is searched for using machine learning methods. We test this approach by simulating the simplest possible case, a 0+1-dimensional scalar field theory in Minkowski space.

Speaker: Enno Carstensen (University of Graz)

main.pdf

10:30 Coffee break

Talks

Convener: Peter Lowdon

11 The end of the rainbow

I present a new formalism for meson physics,
which permits to venture beyond the traditional
rainbow-ladded approximation in a systematic way

Speaker: Joannis Papavassiliou

oberwolz Joannis.pdf

12 Spacelike and Timelike electromagnetic structure of pseudoscalar mesons.

We present a computation of electromagnetic form factors for pseudoscalar mesons within the Bethe–Salpeter framework. For the spacelike region, we employ a flavor-dependent interaction kernel that accounts for dynamical quark mass effects through the quark-gluon vertex structure. This allows for a treatment of the electromagnetic current and accommodates mass asymmetries between quarks. In addition, we explore the pion's timelike electromagnetic form factor using an alternative Bethe–Salpeter truncation adapted to capture resonant and analytic structure in this kinematic regime.

Speaker: Angel Miramontes (University of Valencia)

Miramontes.pdf

12:30 Lunch break

14:00 Guided City Tour

Talks

Convener: Maria Gomez Rocha

13 Minkowski-Space Techniques to Study Light Hadrons

We present a description of the pion and nucleon based on solutions of the Bethe-Salpeter equation (BSE) constructed with phenomenological kernels in Minkowski space. The Nakanishi integral representation is employed to solve the pion BSE in Minkowski space, and various observables are computed. These include the charge form factor, which incorporates higher Fock-state contributions alongside the valence component; in particular, the charge radius associated with the higher Fock states is found to be approximately half a femtometer. We also show the projection of the pion valence state onto the null-plane and present its parton distribution functions and transverse momentum distributions, including an estimated gluonic contribution. The proton structure is described via the light-front projection of the Faddeev–Bethe-Salpeter equation, focusing on the valence parton distribution and its projection onto the null-plane. Finally, future research directions are briefly outlined.

Speaker: tobias frederico (Instituto Tecnologico de Aeronautica)

Frederico_Oberwolz_2025 Tobias Frederico.pdf

14 Properties of hidden- and open-flavour four-quark states from functional methods

The measurement of the $\chi_{c1}(3872)$ as the first heavy-light
four-quark candidate in 2003 was the start to exotic hadron
spectroscopy as we know it today. Over the following decades
many more exotic hadrons were measured and classified. In our work we
use the functional framework of Dyson-Schwinger and Bethe-Salpeter
equations to study the properties of these four-quark states like the mass
and the internal structure. We present novel results for
hidden- and open-flavour four-quark states in the charm and
bottom region.

Speaker: Joshua Hoffer (University Graz)

Oberwölz_Hoffer.pdf

16:30 Coffee break

Talks

Convener: Maria Gomez Rocha

15 Hadronic Structure and Contour Deformations

The internal structure of hadrons 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. We are developing a new method to compute the parton distributions (TMDs and PDFs) from hadronic matrix elements using contour deformations. We will illustrate the method 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) and the four-scalar scattering amplitudes. We finally consider the application of our method to QCD, which includes mesonic Bethe-Salpeter amplitudes and quark four-point functions.

Speaker: Eduardo Ferreira

presentation.pdf

16 Influence of the quark-gluon vertex on the analytic structure of the quark propagator in Landau gauge

The transverse part of the quark-gluon vertex in quenched QCD in Landau gauge is determined by solving a system of Dyson-Schwinger equations. We observe that the angular dependence of the calculated form factors appears to be relatively weak. However, we argue that this does not imply a planar degeneracy for this vertex, as even this slight dependence can significantly alter derived quantities, such as the mass function of the quark propagator. For a self-consistently coupled system of 3PI Dyson-Schwinger equations for the quark propagator and the quark-gluon vertex, we find that the propagator is identical within numerical errors when obtained either from a decoupling or scaling solution input. Furthermore, our results show that the quark propagator is consistent with possessing poles only on the real time-like half-axis.

Speaker: Georg Wieland (University of Graz)

wieland_oberwoelz_25.pdf

18:30 Dinner

20:00 Concert

Wednesday 3 September

Talks

Convener: Jana N. Guenther (University of Wuppertal)

17 Confinement,symmetry, Nc scaling and QCD phase diagram

Confinement,symmetry, Nc scaling and QCD phase diagram

Speaker: Prof. Leonid Glozman

Glozman.pdf

18 Confined but chirally and chiral spin symmetric hot matter

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 Wagenbrunn Robert.pdf

10:30 Coffee break

Talks

Convener: Jana N. Guenther (University of Wuppertal)

19 Goldstone bosons at finite temperature

Temperature has a significant effect on the properties of QFTs with spontaneously broken symmetries, in particular for the massless Goldstone bosons that exist in the vacuum state. In this talk I will discuss recent results which indicate that Goldstone modes persist at high temperatures, even if the symmetry is restored, and that they have the properties of screened massless excitations, so-called thermoparticles. This has important implications for the phase structure of QFTs at finite temperature.

Speaker: Peter Lowdon

Oberwolz_Lowdon.pdf

20 Machine Learning Fixed-Point Actions for Lattice Gauge Theory

Fixed-point actions offer a powerful way to reduce discretization artifacts in lattice gauge theory, but their practical use has long been limited by the difficulty of finding accurate parametrizations. We address this challenge using machine learning with gauge-equivariant convolutional neural networks, which can represent general gauge-invariant structures on the lattice. This allows us to construct classically perfect actions for 4D SU(3) gauge theory that suppress lattice artifacts even on coarse lattices. The learned actions are suitable for both gradient flow and Hybrid Monte Carlo simulations, opening new possibilities for efficient and systematically improved lattice studies.

Speaker: Andreas Ipp (TU Wien)

oberwoelz_ipp_2025.pdf

12:30 Lunch

14:00 Excursion

Hike and dinner ("Brettljause")

Thursday 4 September

Talks

Convener: Liliana Apolinario (LIP (PT))

21 Non-Equilibrium Dynamics in the Early Universe

I will first briefly review the current state-of-the-art in calculating non-equilibrium processes in the early Universe, particularly in the context of baryogenesis and dark matter production. I will then focus on dark matter freeze-in, where various semi-classical Boltzmann approaches are employed in the literature and require careful scrutiny. I will present our recent calculation of freeze-in production for a real scalar dark matter candidate, based on the closed time path (CTP) formalism, deriving the non-equilibrium dynamics in the thermal plasma from first principles. I will show that the sensitivity of the freeze-in mechanism to the vacuum mass of the parent particle requires a treatment beyond the Hard-Thermal-Loop (HTL) approximation. To this end, I will present our calculation based on the leading-order contribution in the loop expansion of the 2PI effective action, using 1PI-resummed propagators. To include all leading-order contributions to the interaction rate in the ultra-relativistic regime, I will also present our extended calculation that effectively incorporates the Landau-Pomeranchuk-Migdal (LPM) effect, providing the new state-of-the-art calculation. Finally, I will compare these results with those obtained from the HTL approximation and various semi-classical Boltzmann approaches, quantifying their associated uncertainties.

Speaker: Prof. Julia Harz (Johannes Gutenberg University Mainz)

Oberwoelz2025_Harz.pdf

22 Constraints on the QCD Phase Diagram from Lattice QCD

Lattice QCD provides a unique, non-perturbative framework to map out the QCD phase diagram from first principles. This talk will outline what can—and cannot—currently be determined about the QCD phase diagram using lattice simulations. I will review how precise results for the equation of state and the transition temperature are obtained at vanishing baryon density. The challenges of extending these calculations to finite baryon density, where the sign problem limits straightforward simulations, will be discussed along with methods to constrain the location of a possible critical end point.

Speaker: Jana N. Guenther (University of Wuppertal)

ow_guenther.pdf

10:30 Coffee break

Talks

Convener: Liliana Apolinario (LIP (PT))

23 Spectral properties of QCD

In this talk the spectral properties of QCD are discussed. This includes the existence or non-existence of the Källén-Lehmann (KL) representation for the fundamental fields (gluons, ghosts and quarks) as well as the respective consequences for observables such as scattering amplitudes or transport coefficients. Specifically, the KL representation of the quark and its dependence on the interaction strength in QCD is discussed.

Speaker: Jan M. Pawlowski

talkOberwoelz-2025_pawlowski.pdf

24 Color Superconductivity in Two-Flavor QCD and Its Role in Neutron Stars

We explore the emergence of color superconductivity in two-flavor QCD and its implications for the equation of state of dense matter inside neutron stars. Employing a quark-meson-diquark model truncation within the functional renormalization group framework, we study the interplay between diquark and chiral condensates and the resulting superconducting phase at high baryon density. Our findings provide insights on the QCD phase structure under extreme conditions and point to color-superconducting quark matter as a possible component of neutron star cores and related astrophysical phenomena.

Speaker: Bernd-Jochen Schaefer

schaefer_092025 Bernd Schaefer.pdf

12:30 Lunch

Talks

Convener: Markus Huber

25 Quantum Computing – better and faster or just more hype?

Quantum Computing – better and faster or just more hype?

Speaker: Prof. Gerhard Hellstern (DHBW Stuttgart)

Talk_Hellstern Gerhard Hellstern.pdf

15:30 Coffee break

Colloquium

Convener: Markus Huber

26 Chiral Quark Dynamics

Speaker: Prof. Hugo Reinhardt (Tübingen University)

Reinhardt.pdf

27 Functional excursions: from quark models for nucleons to classical liquid state physics

Functional excursions: from quark models for nucleons to classical liquid state physics

Speaker: Prof. Martin Oettel (Universität Tübingen)

28 Columbia plot, critical point and bound states in dense QCD

Converging results from different approaches locate the critical end point (CEP) of QCD
at large chemical potential, i.e. in the realm of dense QCD. We summarise recent
theoretical results within functional methods on the location of the CEP and its
variation under systematic changes of the light and strange quark masses. We furthermore
discuss the physics at large chemical potential including the properties of bound states
and the possible appearance of interesting new phases.

Speaker: Prof. Christian Fischer (University of Giessen, Germany)

Fischer_v1.pdf

19:00 Dinner

Friday 5 September

Talks

Convener: Bernd-Jochen Schaefer

29 Quantum Chromodynamics in Dense Media

Speaker: Sonia Kabana (Instituto De Alta Investigación, Universidad de Tarapacá (CL))

SoniaKabana_talk_Oberwoelz2025_v8.pdf

30 Zubarev’s Nonequilibrium Statistical Operator Approach – Applications to Chemical Freeze-out

The exploration of the phase diagram of quantum chromodynamics (QCD) is performed in
ultrarelativistic heavy-ion collision experiments, whereby the LHC and SPS facilities at CERN
Geneva and the RHIC at Brookhaven National Laboratory provide high-quality data on the
production of particles (hadrons and nuclei). While for the interpretation of the data a statistical
equilibrium approach (hadron resonance gas) is generally accepted, a quantum statistical description
of these strong nonequilibrium processes is needed, based on the time-dependent statistical operator
ρ(t).
In this talk, we outline Zubarev’s method of the nonequilibrium statistical operator (NSO) [1,2] as a
fundamental approach to describe nonequilibrium processes and present recent applications to
understand chemical freeze-out in the QCD phase diagram. We trace the origin of the freeze-out
lines to their correlation with the Mott lines for the dissociation of bound states in a hot and dense
medium [3-6].
[1] Zubarev, Morozov, Röpke, Statistical Mechanics of Nonequilibrium Processes II, Wiley (1997)
[2] D. Blaschke et al. (Eds.), Nonequilibrium Phenomena in Strongly Correlated Systems, Particles
(2020)
[3] Dönigus et al., PRC 106 (2022) 044908
[4] Blaschke et al., PLB 860 (2025) 139206
[5] Vitiuk et al., arXiv:2409.09019, PRC (2025)
[6] Röpke et al., arXiv:2411.00535
) supported by NCN under grant number 2021/43/P/ST2/03319
*) supported by a honorary stipend from the Foundation for Polish Science within the Alexander
von Humboldt program under grant No. DPN/JJL/402-4773/2022

Speaker: David Blaschke

10:30 Coffee break

Talks

Convener: Bernd-Jochen Schaefer

31 Study of heavy flavored $B$ meson system in a QCD-inspired model

Recognizing that flavor changing processes can probe new physics at scales beyond the reach of current experiments, we analyze semileptonic heavy meson, $B$, $B_s$ and $B_c$ decays using \emph{Relativistic Independent Quark Model - a QCD inspired model} emphasizing the harmonic potential model-dependent analysis. Our predicted branching fractions and physical observables such as $P_{\tau}(D_{(s)}^{(*)})$, $F_{L}(D_{(s)}^{(*)})$ in the $B$ decays show good agreement with the lattice and experimental measurements. In particular, our predictions for $P_{\tau}(D^{(*)})$ in $B_c$ decays offer valuable information in the absence of lattice data for this observable. We perform a comprehensive analysis of the form factors across the whole accessible kinematic range of $q^2$. Furthermore, we evaluated the clean ratios of $B_s$ to $B_0$ in the semimuonic mode that are in accordance with the LHCb measurements, and support the validity of the SU(3) flavor symmetry. While the lack of clear deviations in high energy collider data challenges the TeV - scale NP paradigm, $B$ meson decays always remain a powerful probe of NP, especially beyond the reach of direct searches. Therefore, while lattice QCD remains the gold standard for theoretical predictions, QCD-inspired models serve as valuable alternatives in regions where lattice results are unavailable.

Speaker: Ms Sonali Patnaik (National Institute of Science Education and Research)

Sonali.pdf

32 Challenges of hadron spectroscopy from lattice QCD

I will briefly review the status and challenges of excited and exotic hadron spectroscopy using lattice QCD based on Eucledian-time. Selected results on exotic hadrons will be discussed. The challenges motivate progress for non-perturbative studies based on real-time evolution.

Speaker: Sasa Prelovsek Komelj

prelovsek_oberwolz_25.pdf

12:30 Lunch break

Talks

Convener: Sasa Prelovsek Komelj

33 Simulating scattering amplitudes

Speaker: Simon Platzer (University of Graz (AT))

34 The role of double-heavy tetraquarks (dimesons)

The discovery of the dimeson T_cc^+ at CERN 2021 at the predicted energy supported the successful application of the quark model beyond the 2-body and 3-body hadronic systems. Now, T_bb^- (and possibly T_bc^0) are expected to be strongly bound and decay only weakly. The search for T_bc^0 and T_bb^- continues and should be strongly encouraged. The reconstruction of the plethora of weak decays might test the influence of the c- and b- rich environment on the evolution of tetraquarks.

Speaker: Mitja Rosina (University of Ljubljana)

Rosina Mitja Rosina.pdf

35 Functional Renormalization of QCD in 1+1 dimensions

TBA

Speaker: Eric Oevermann (Friedrich Schiller University Jena)

Oevermann_QCD2d_with_FRG.pdf

36 Charged polarons at finite momentum

In the context of ultracold gases, hybrid ion–atom interaction systems, where charged polarons are formed, have become of significant interest for many fields, including condensed matter physics, solid-state systems, transport phenomena, quantum information, and quantum simulation. In this work, we investigate the properties of a charged polaron formed by an ion with finite momentum immersed in a weakly interacting Bose–Einstein condensate (BEC). In contrast to previous studies, the finite momentum of the ion enables us to go beyond the contact interaction approximation for the ion–atom potential. The polaron is going to have a finite momentum then, employing second-order perturbation theory, we characterize the effective mass, self-energy, bound-state formation and Cherenkov radiation as functions of the tunable interaction parameters. Our results are compared to those obtained in the static polaron scenario, finding notable differences that could be of both theoretical and experimental relevance for ongoing research.

Speaker: Grover David Andrade Sánchez (IF, UNAM)

Andrade Grover Andrade.pdf

Andrade Grover Andrade.pdf

Andrade Grover Andrade.pptx

37 Quantum statistical analysis of thermodynamic relations in relativistic spin hydrodynamics

We demonstrate, by providing two specific examples, that the local differential thermodynamic relations used as educated guesses in relativistic hydrodynamics with spin, do not hold even at global thermodynamic equilibrium. We show, by using a rigorous quantum statistical method, that for massless free fermions and massive free fermions with rotation and acceleration at global thermodynamic equilibrium, the derivative of the pressure function with respect to the spin potential differs from the spin density and acquires a correction of the same order. Such correction cannot be eliminated by any redefinition of the entropy current, a so-called entropy-gauge transformation. Therefore, for an accurate determination of the constitutive relations in relativistic spin hydrodynamics, the traditional method of assuming differential thermodynamic relations is not appropriate.

Speaker: Dr Rajeev Singh (West University of Timisoara, Romania)

ThermodynamicRelations_Rajeev.pdf

16:30 Coffee break

Talks

Convener: Sasa Prelovsek Komelj

38 No black holes from light

General Relativity theoretically allows the formation of black holes through the gravitational collapse of purely electromagnetic radiation. However, this scenario would involve electromagnetic strengths surpassing the critical Schwinger limit, resulting in the generation of electron-positron pairs. This quantum phenomenon counteracts the collapse, with the created particles scattering out of the collapsing region, carrying their energy. Here, we show that this dissipative effect alone is enough to prevent the formation of black holes from light in the non-classical regime.

Speaker: Dr Álvaro Álvarez Domínguez (Universidad Complutense de Madrid & IPARCOS)

No black holes from light (Austria).pdf

39 Closing

19:00 Heraeus Evening