# XXXII International (ONLINE) Workshop on High Energy Physics "Hot problems of Strong Interactions"

Europe/Moscow
,
Description

Logunov Institute for High Energy Physics (Protvino, Moscow region, Russia) of  National Research Centre "Kurchatov Institute" (in collaboration with IZMIRAN, JINR and University of Georgia)- is organizing the XXXII International (ONLINE) Workshop on High Energy Physics “Hot problems of Strong Interactions”, November 9-13, 2020.

The purpose of this Workshop is to give participants an opportunity to present results and discuss various aspects of the strong interactions phase diagram as well as of heavy quarks physics.

In this unusual time we consider it important to provide a possibility of live discussions and exchange of ideas on contemporary problems of high-energy physics.

## Topics to be discussed

### QCD under extreme conditions, Phases of Quark/Baryon Matter

• Strong-interacting matter at finite temperature
• QCD phase structure at non-zero baryon density
• Approaches to sign problem at non-zero baryon density
• QCD phase diagram under strong external magnetic field
• Phase diagram in the context of heavy-ion collisions
• QCD phase diagram in astrophysics
• Theoretical ideas and experimental searches of the critical point
• Non-zero isospin density and meson condensation
• QCD phase structure with chiral imbalance
• Effects of rotation in QCD phase diagram
• Anomalous transport phenomena and related issues: CME, CSC CVE, ...
• Inhomogeneous phases in strongly interacting matter
• Experimental results and future facilities

### Physics of heavy quarks

• New findings in heavy-quark spectroscopy
• Heavy quarkonia
• Doubly heavy baryons
• Tetraquarks, pentaquarks
• Heavy-quark production
• Heavy flavours in QGP

G. Aarts (Swansea U.)
D. Blaschke (Wroclaw U.)
V. Braguta (JINR & MISIS)
E. Bratkovskaya (GSI & Frankfurt Univ.)
K. Bugaev, BITP
E. Braaten (Ohio State U.)
Ph. de Forcrand  (CERN)
D. Ebert (Berlin U.)
K. Fukushima (Tokyo U.)
F. Karsch (Bielefeld U.)
K. Klimenko (IHEP)
A. Likhoded (IHEP)
A. Nakamura (FEFU)
R. Pisarski (BNL)
I. Shovkovy (Arizona State U.)
O. Teryaev (JINR, ITEP)
V. Zakharov (ITEP)

Structure of the workshop

Two sessions with 4-5 invited talks of 30 minutes duration will be arranged every day. After each session one hour will be devoted to moderated open discussion.

A distinguishing feature of this workshop is that a 1-hour discussion session after each section of talks will be arranged, where new developments and results presented in the talks as well as long-standing problems and questions will be discussed. It will be moderated by the Discussion Leader.

## IMPORTANT DATES

• November 13, 2020 - end of registration
• November 1, 2020 - end of abstract submission
• November 7, 2020 - end of presentation submission
• November 9, 2020 - start of the Workshop

Please, send us the title of your talk (even if very preliminary) before November 1, 2020 and try to upload your presentation by the web interface (will be open after October 1, 2020) or send it by e-mail to hepft2020-hposi-questions-AT-ihep.ru.

## Participation

Participation with talks is by invitation of the Organizing Committee.
In the case of a proactive request the decision is made by the organizing committee.

The sessions will be online by zoom. The link will be sent to all the participants and posted on the site.

There is no registration fee.

Participants
• Abdel Magied Abdel Aal DIAB
• Abdel Tawfik
• Abhinav Choudhury
• Akio Tomiya
• Akram Ghaffarian
• Alejandro Ayala
• Aleksi Kurkela
• Aleksi Vuorinen
• Alexander Andrianov
• Alexander Nikolaev
• Alexandra Friesen
• Alexey Ermakov
• Alexey Luchinsky
• Alfiia Mukhaeva
• Amal Ait El Djoudi
• Amber Jamal
• Amit Kumar
• Ana Gabriela Grunfeld
• Anastasia Golubtsova
• Anatoly Sidorin
• Andreas Bauswein
• Andreas Wipf
• Andrei Kataev
• Andrey Kotov
• Angel Gómez Nicola
• Angel Sanchez
• Anirban Lahiri
• AnkIta Budhraja
• Anton Trunin
• Antonio Smecca
• Arata Yamamoto
• Arghya Mukherjee
• Aric Hackebill
• Aritra Das
• Artem Roenko
• Artyom Vasiliev
• Arunima Swain
• Arvind Kumar
• Ashwani Saraswat
• Atefeh ostovar
• Atsushi Nakamura
• Bachir Moussaoui
• Bastian Brandt
• Ben Page
• Benjamin Svetitsky
• Bernard Bakker
• Bernd-Jochen Schaefer
• Bhoomika Pandya
• Biagio Lucini
• BingJun Zuo
• Bithika Karmakar
• Bo Feng
• Bochra Mezigheche
• Bruno Rocha
• Carolin Riehl
• Chihiro Sasaki
• Chowdhury Aminul Islam
• Christian Fischer
• Christian Rohrhofer
• Christof Gattringer
• Daria Prokhorova
• David Alvarez-Castillo
• David Anthony Clarke
• David Blaschke
• David FUSEAU
• Debashree Sen
• Debasish Das
• Debjani Banerjee
• DEEPTAK BISWAS
• Defu Hou
• Denis Kuznedelev
• Denis Shohonov
• Diana Crihan
• Dimitrios Bachtis
• Dmitri Peresunko
• Dmytro Oliinychenko
• Dyana Duarte
• Edgar Dominguez Rosas
• Efrain J Ferrer
• Eleazar Cuautle
• Elena Bratkovskaya
• Eliel Seke
• Elizaveta Nazarova
• Eric Ballabene
• Eric Braaten
• Essma Redouane salah
• Etsuko Itou
• Fabian Rennecke
• Fatemeh Taghavi-shahri
• Francesca Cuteri
• Frithjof Karsch
• Gabriel Sophys
• Gabriele Coci
• Gayatri Ghosh
• Georgios Filios
• Gergely Endrodi
• Gergely Marko
• Germán Lugones
• Gert Aarts
• Gustavo Antonio Pires Vaccani
• Gustavo Contrera
• Gustavo Viteri
• Hai-Tao Shu
• Hamid Nanda
• Hee Sok Chung
• Helena Kolesova
• Heng-Tong Ding
• Hesham Abdelbagi
• Hiromu Shimoji
• Iasmin Castegnaro
• Igor Shovkovy
• Ilia Grishmanovskii
• Ilya Kudrov
• Iori Nagase
• Jacobo Ruiz de Elvira
• Jamal Jalilian-Marian
• Jan Bauer
• Jan Horak
• Jan M. Pawlowski
• Jan Steinheimer
• Jana N. Guenther
• Jayanta Dey
• Jens Oluf Andersen
• Ji-Chong Yang
• Jishnu Goswami
• Joana Sodré
• Jorge Jaber-Urquiza
• José Luis Hernández
• Juan Torres-Rincon
• Julian Bernhardt
• Julian Lenz
• Julian Urban
• Karl Landsteiner
• Kazem Azizi
• KAZI PARVEZ ISLAM
• Kazuya Mameda
• Keh-Fei Liu
• Kenji Fukushima
• Koichi Hattori
• Konstantin Klimenko
• Konstantin Maslov
• Konstantinos Anagnostopoulos
• Kurosh Javidan
• Kyrill Bugaev
• Laurin Pannullo
• Lennart Kurth
• Letizia Parato
• Luca Tagliacozzo
• Lucia Oliva
• Luis Altenkort
• Luis Hernández
• Mahfuzur Rahaman
• Maksim Ulybyshev
• Mandeep Kaur
• Manfried Faber
• Manisha Kumari
• Manu Kurian
• Marc Wagner
• Marc Winstel
• Marco Ruggieri
• Maria Paola Lombardo
• Maria Paola Lombardo
• Mariana Araújo
• Mark Baker
• Markus Huber
• Marouane habib HERAIZ
• Martin Jakob Steil
• Martin Mojahed
• Massimo D'Elia
• Massimo Mannarelli
• Mathieu Kaltschmidt
• Matthias Hanauske
• Maxim Chernodub
• Mehmet DEMİRCİ
• Mei Huang
• Michael Buballa
• Michael Mandl
• Michael Strickland
• Minhajul Islam
• Mugdha Sarkar
• Muniba Fatima
• Mykyta Dmytriiev
• Nalimov Mikhail
• NANDINI PATEL
• Natalia Kolomoyets
• Nguyen Hoang Vu
• Nico Santowsky
• niloufar arami
• Nizami Abdulov
• Norberto Scoccola
• Nugzar Makhaldiani
• Olaf Kaczmarek
• Oleg Rogachevsky
• Oleg Teryaev
• Oleh Savchuk
• Oleksii Ivanytskyi
• Olga Soloveva
• Orlando Oliveira
• Pallavi Kalikotay
• PARVATHI P
• Pascal Gunkel
• Paula Hillmann
• Pavel Mitkin
• Pedro Sanson
• Percy Cáceres
• Peter Petreczky
• Philipp Isserstedt
• Philippe de Forcrand
• Pierre Moreau
• Pietro Faccioli
• Pihan Grégoire
• Poonam Jain
• pracheta singha
• Prottoy Das
• Qingwu Wang
• Rafaela Conz da Costa
• Rahmaneh ostovar
• Rajesh Kumar
• Ranjita Kumari Mohapatra
• RASHID KHAN
• Rene Bellwied
• Renwick Hudspith
• Ricardo Farias
• Ritesh Ghosh
• Rob Pisarski
• Roman Rogalyov
• Roman Ryutin
• Roman Zhokhov
• Rudolf Faustov
• Rudolf Golubich
• Sabiar Shaikh
• Sabyasachi Ghosh
• Sachio Iwasaki
• Sahil Ugale
• Sana Mekhalfa
• Sandip Maiti
• Sarthak Duary
• Saumia Pandiat
• Semeon Valgushev
• Sergei Nedelko
• Shu Lin
• Simone Romiti
• Singh Rajeev
• Smita Chakraborty
• Snigdha Ghosh
• Somenath Pal
• SOUNAK pal
• Stefano Carignano
• Suman Kumar Panja
• Sumana Bhattacharyya
• Suraj Kumar Rai
• Taesoo Song
• Tamal Kumar Mukherjee
• Tamaz Khunjua
• Tamer Boz
• Ting-Wai CHIU
• Tomas Brauner
• Tsutomu Ishikawa
• Udita Shukla
• Valentin Zakharov
• Valery Rubakov
• Veronica Dexheimer
• Victor Braguta
• Victor E. Ambrus
• Viljami Leino
• Vitaly Bornyakov
• Vivek Kumar Tiwari
• Vivian Incera
• Volodymyr Vovchenko
• Waseem Bashir
• Wei Chen
• Wen-Li Yuan
• Will Gyory
• William Tavares
• Wolfgang Unger
• Xiao-Ming Xu
• Xiaofeng Luo
• Xu-Guang Huang
• YEHYA RASOOL
• Yogesh Kumar
• Yoshimasa Hidaka
• Yu Zhang
• Yuki Fujimoto
• Yun Guo
• Yuri Ivanov
• Yuri Kharlov
• Zalak Shah
• Zheng Zhang
• Zhongbo Kang
• Евгений Бердников
• Ирина Aref'eva
• Роман Жохов
• Monday, 9 November
• 10:50 11:00
Opening session

Opening session

• 10:50
• 10:55
Opening address & Format remarks (R. Zhokhov) 5m
• 11:00 14:00
Session 1: Strong-interacting matter at finite temperature: Strong-interacting matter at finite temperature

Chairperson: Frithjof Karsch

• 11:00
Universal (?) scaling of QCD from Wilson femions 30m

We study the scaling properties of QCD in temperature and mass
close to the thermal crossover, and for quark masses ranging from the heavy quark regime to the physical values. The lattice results are obtained in the fixed scale approach, either with anisotropic simulations with Nf=2+1 flavours,
and with simulations of Nf = 2 +1 + 1 flavours at maximal twist. We note that a simple combination of chiral observables reduces the additive renormalizations and the contribution from the regular terms in the equation of state, thus helping the assessment of the hypothesized universal behaviour.

Speaker: Prof. Maria Paola Lombardo (INFN Firenze)
• 11:30
Universal scaling close to chiral limit of QCD 30m

Chiral phase transition has been a topic of interest over decades
and order of the chiral phase transition has an effect on the global
phase diagram of QCD. In this talk I will review some of our recent
calculations towards the limit of 2 massless flavors. I shall
and then show how our calculation is able to throw some light on
the long standing debate about the order of the chiral phase
transition. I shall also show that the gluonic observables
and conserved charge fluctuations towards the chiral limit, can
be well described by the scaling behavior of an energy like
observable w.r.t. chiral symmetry.

Speaker: Dr Anirban Lahiri (Biefefeld U.)
• 12:00
Fluctuations and the QCD phase diagram from functional methods 30m

We summarise recent theoretical results on the QCD phase diagram and the properties
of QCD's critical point based on a combination of lattice QCD and Dyson-Schwinger
equations.
Using lattice input for the quenched gluon propagator, our approach correctly reproduced
and predicted Nf=2+1 flavour lattice results for the quark condensate and the unquenched
electric and magnetic gluon propagator at zero chemical potential. At chemical potential
up to $\mu_B/T$<3 our approach and extrapolations using lattice QCD both confirm an
analytic crossover from the hadronic phase into the QGP. Beyond this region we see a
critical end point at ($T^c,\mu_B^c$)=(120,500) MeV, which is neither very sensitive
to additional charm quark contributions nor to corrections from virtual baryons.
We furthermore present new results for baron number fluctuations. We discuss the changes
of ratios of fluctuations up to fourth order along and below the transition line for
temperatures and baryon chemical potential up to and beyond the critical end point.
Comparing with preliminary STAR data for the skewness and kurtosis ratios,
our results are compatible with the scenario of a critical end point at
large chemical potential and slightly offset from the freeze-out line.
We also discuss the caveats involved in this comparison.

Speaker: Prof. Christian Fischer ( Institut für Theoretische Physik Universität Gießen)
• 12:30
Advances on the QCD phase diagram from Ward Identities and Effective Theories 30m

I will review recent advances on the QCD phase diagram, regarding mostly the nature of the chiral phase transition and its interplay with $U(1)_A$ restoration. Ward Identities and Effective Theories will be the main theoretical tools. The former allow to establish the thermal behaviour of chiral and $U(1)_A$ partners whereas the latter turns out to be quite fruitful for certain observables of interest such as scalar and topological susceptibilities or to study chiral imbalance. Comparison to recent lattice data will be one of the main guidelines for these approaches.

• 13:00
Correlated Dirac eigenvalues and axial anomaly in chiral symmetric QCD 30m

In this talk I will present our very recent work based on [1].
We introduce novel relations between the derivatives ($\partial^{n}{\rho(\lambda,m_l)}/{\partial m_l^{n}}$) of the
Dirac eigenvalue spectrum ($\rho(\lambda,m_l)$) with respect to the light sea quark mass ($m_l$)
and the $(n+1)$-point correlations among the eigenvalues ($\lambda$) of the massless
Dirac operator. Using these relations we present lattice QCD results for
$\partial^{n}{\rho(\lambda,m_l)}/{\partial m_l^{n}}$ ($n=1, 2, 3$) for $m_l$ corresponding to pion masses
$m_\pi=160-55$ MeV, and at a temperature of about 1.6 times the chiral phase
transition temperature. Calculations were carried out using (2+1)-flavors of highly
improved staggered quarks with the physical value of strange quark mass, three
lattice spacings $a=0.12, 0.08, 0.06$ fm, and lattices having aspect ratios $4-9$.
We find that $\rho(\lambda\to0,m_l)$ develops a peaked structure. This peaked
structure arises due to non-Poisson correlations within the infrared part of the
Dirac eigenvalue spectrum, becomes sharper as $a\to0$, and its amplitude is
proportional to $m_l^2$. We demonstrate that this $\rho(\lambda\to0,m_l)$ is
responsible for the manifestations of axial anomaly in 2-point correlation
functions of light scalar and pseudo-scalar mesons. After continuum and chiral
extrapolations we find that axial anomaly remains manifested in 2-point correlation
functions of scalar and pseudo-scalar mesons in the chiral limit.

[1] H.-T. Ding, S.-T. Li, Swagato Mukherjee, A. Tomiya, X.-D. Wang, Y. Zhang, arXiv:2010.14836.

Speaker: Ms Yu Zhang (CCNU)
• 13:30
How can one tell if there is quark matter in neutron stars 30m
Speaker: Prof. Kurkela Aleksi (University of Stavanger)
• 14:00 14:10
Break

Break

• 14:10 15:10
Discussion session 1

Discussions

• 14:10
Discussion session (DL: Frithjof Karsch): Strong-interacting matter at finite temperature 1h
• 15:10 19:00
Break

Break

• 19:00 22:00
Session 2: QCD phase diagram under strong external magnetic field (NOTE! late starting time)

Chairperson: Alejandro Ayala

• 19:00
Magnetized QCD phase diagram from the point of view of chiral symmetry restoration 30m

In this talk, we present an analysis performed within the Linear Sigma Model coupled to quarks, where the restoration of the chiral symmetry is studied both at finite temperature and baryon chemical potential in the presence of a constant in time and uniform magnetic field. The features of this transition are studied in the QCD phase diagram. We discuss the modification of the transition lines in the phase diagram induced by the field strength.

Speaker: Dr Luis Hernandez (Instituto de Ciencias Nucleares, UNAM)
• 19:30
Neutral meson properties in hot and magnetized quark matter 30m

We discuss the properties of neutral mesons using effective models of QCD: Nambu-Jona--Lasinio (NJL) model and Linear Sigma model with quarks (Lsmq). We show that when accounting for the effects of the magnetic field on the model couplings, the neutral pion mass decreases monotonically as a function of the field strength. We find an excellent agreement with recent lattice QCD calculations, reproducing the monotonically decreasing trend with the field strength.

Speaker: Prof. Ricardo Farias (UFSM)
• 20:00
Axion Polariton in Magnetized Dense Quark Matter 30m

In this talk we review the topological properties and possible astrophysical consequences of a spatially inhomogeneous phase of quark matter, known as the Magnetic Dual Chiral Density Wave (MDCDW) phase, that can exist at intermediate baryon density in the presence of a magnetic field. Going beyond mean-field approximation, we show how linearly polarized electromagnetic waves penetrating the MDCDW medium can mix with the phonon fluctuations to give rise to two hybridized modes of propagation: a rotated photon and a massive axion polariton. The formation of axion polaritons in the MDCDW core of a neutron star can add mass to the star via the Primakoff effect, eventually triggering the star collapse. This mechanism provides a possible solution to the missing pulsar problem in the galactic center.

Speaker: Prof. Efrain J Ferrer (Univ. of Texas at Rio Grande Valley (UTRGV))
• 20:30
Magnetic susceptibility of QCD matter 30m

In this talk I will report on a new method to determine the magnetic susceptibility of thermal QCD matter on the lattice. The method employs current-current correlators evaluated at zero magnetic field, thereby circumventing problems of previous approaches related to magnetic flux quantization. Using the susceptibility, the equation of state at low magnetic fields is reconstructed and parameterized in a manner useful for model approaches. If time allows, a decomposition of the susceptibility into spin- and orbital angular momentum-related contributions will be discussed.

Speaker: Prof. Gergely Endrodi (University of Bielefeld)
• 21:00
Magnetic field dependence of the NJL coupling from lattice QCD 30m

We address the question of the magnetic phase diagram of strong interactions, where chiral effective model descriptions show a different picture compared to lattice QCD results. We propose a physically motivated improvement scheme for effective models based on continuum extrapolated lattice data. We measured the magnetic field dependence of the baryon spectrum in full QCD simulations, which is fed as an input for the PNJL model to define a magnetic running coupling. This results in a corrected magnetic behaviour for other observables.

Speaker: Dr Gergely Marko (University of Bielefeld)
• 21:30
"Confinement and deconfinement in a magnetic background field" 30m

I will review recent results on the effects of a magnetic background field on the confining properties of strong interactions and on the deconfinement phase transition

Speaker: Prof. Massimo D'Elia (University of Pisa and INFN)
• 22:00 22:10
Break

Break

• 22:10 23:10
Discussion session 2
• 22:10
Discussion session (DL: Igor Shovkovy): QCD phase diagram under strong external magnetic field 1h
• Tuesday, 10 November
• 11:00 14:00
Session 3: QCD phase diagram in astrophysics

Chairperson: David Blaschke

• 11:00
Model-independent approach to the neutron-star-matter equation of state 30m

I will discuss recent developments in inferring the equation of state of zero-temperature beta-equilibrated QCD matter using only ab-initio theoretical results at low and high densities together with robust observational data. In particular, I will introduce a novel method for interpolating the equation of state that allows one to accurately keep track of the speed of sound of neutron-star matter, thereby facilitating a more detailed analysis of the properties of matter in the cores of neutron stars of different masses. Using results obtained with the new interpolation scheme, I will argue that the matter located in the centers of massive neutron stars is likely to exhibit properties consistent with those of deconfined quark matter.

Speaker: Prof. Aleksi Vuorinen (University of Helsinki)
• 11:30
Gravitational-Wave Signatures of the Hadron-Quark Phase Transition in Binary Compact Star Mergers 30m

With the first detection of gravitational waves from a binary system of neutron stars GW170817, a new window was opened to study the properties of matter at and above nuclear-saturation density. Reaching densities a few times that of nuclear matter and temperatures up to 100 MeV, such mergers also represent potential sites for a phase transition from confined hadronic matter to deconfined quark matter. The gravitational wave signatures of the production of quark matter, both during the inspiral (see PRD 99 (10), 103009 (2019)), merger and postmerger phase of a compact star merger will be in the focus of this talk. The presented results are based on fully general-relativistic hydrodynamic simulations and employing several suitably constructed equation of states that include a hadron-quark phase transition (see Phys.Rev.Lett. 122 061101 (2019), Phys.Rev.Lett. 124, 171103 (2020)).

Speaker: Dr Dr. Matthias Hanauske (Goethe University Frankfurt, Institute for Theoretical Physics)
• 12:00
The hadron-quark phase transition and neutron star mergers 30m

The first unambiguous observation of a neutron star merger in 2017 has highlighted the prospect to learn about incompletely known properties of neutron stars and high-density matter. We will discuss the impact of the hadron-quark phase transition on observables of neutron star mergers. In turn, future observations of neutron star merger events can be employed to understand whether or not the hadron-quark phase transition occurs in neutron stars. In particular, it will be possible to constrain the onset density of the phase transition.

Speaker: Prof. Andreas Bauswein
• 12:30
Pasta phase in hybrid hadron-quark stars 30m

We investigate the effect of the formation of the structured mixed phase (pasta phase) on the quark-hadron phase transition. The results of the full numerical solution with pasta phases are compared with those of an interpolating construction used in previous works, for which we demonstrate an adequate description of the numerical results. For each pair of RMF models for quark and hadron matter used in this work, we determined the critical value of the surface tension, above which the phase transition becomes close to the Maxwell construction. This result is applied to demonstrate the effect of pasta phases on the structure of hybrid compact stars and the robustness of a possible third family solution.

Speaker: Dr Konstantin Maslov (JINR)
• 13:00
Second look to the Polyakov Loop Nambu-Jona-Lasinio model at finite baryonic density 30m

We revisit the Polyakov Loop coupled Nambu-Jona-Lasinio model that maintains the Polyakov loop dynamics at zero temperature, which is the most interesting for astrophysical applications. For this purpose we re-examine potential for the deconfinement order parameter at finite baryonic densities. Secondly, and the most important, we explicitly demonstrate that naive modification of this potential at any temperature is formally equivalent to assigning a baryonic charge to gluons. We develop a general formulation of the present model which is free of the discussed defect and is normalized to asymptotic of the QCD equation of state given by $\mathcal{O}(𝛼_𝑠^2)$ perturbative results. We also demonstrate that incorporation of the Polyakov loop dynamics to the present model sizably stiffens the quark matter equation of state supporting an existence of heavy compact stars with quark cores.

Speaker: Dr Oleksii Ivanytskyi
• 13:30
Future Compact star observations that could confirm the existence of a Critical End Point in the QCD phase diagram 30m
Speaker: Dr David Alvarez-Castillo (JINR, Dubna)
• 14:00 14:10
Break

Break

• 14:10 15:10
Discussion session 3
• 14:10
Discussion session (DL: David Blaschke): QCD phase diagram in astrophysics: "CEP or crossover all over - does it matter?" 1h
• 15:10 16:00
Break

Break

• 16:00 19:30
Session 4: Anomalous transport phenomena and related issues: CME, CSC CVE, … (celebrating the 80th birthday of Valentin Zakharov)

Chairperson: Oleg Teryaev

• 16:00
Spin and Anomaly 30m
Speaker: Prof. Oleg Teryaev (JINR, Dubna)
• 16:30
Chiral magnetic effect and conductivity of quark-gluon plasma in external magnetic field 30m

In this talk we discuss chiral magnetic effect - one of the most actively discussed macroscopic
manifestations of the chiral anomaly. One of the consequences of the chiral magnetic effect is the growth of the conductivity in magnetic field. We present results of the lattice measurements of the conductivity of quark-gluon plasma in external magnetic field, both in parallel and perpendicular directions. The results confirm the existence of the chiral magnetic effect. Using these results, relaxation time of the chiral charge is also estimated.

Speaker: Dr Andrey Kotov (Jülich Forschungszentrum)
• 17:00
Zilch Vortical Effect, Berry Phase, and Kinetic Theory 30m
Speaker: Dr Andrey Sadofyev (University of Santiago de Compostela)
• 17:30
Topological charge and chiral density production in the early stage of high energy nuclear collisions 30m

We study the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions. Topological charge is related to the gauge invariant E · B where E and B denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We discuss how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities as well as the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be produced during the pre-equilibrium stage. Finally, we comment on one possible phenomenological impact of chiral density production in the early stage, namely photons that would be produced via the chiral magnetic effect.

Speaker: Prof. Marco Ruggieri (Lanzhou University)
• 18:00
Fermion helicity vs. chirality: transport, thermodynamic, and spin-polarization effects 30m

Helicity is a classically conserved quantity that can be used, in addition to and independently of the (vector) charge and chirality, to characterize thermodynamic ensembles of Dirac fermions. We demonstrate the existence of new nondissipative transport phenomena, helical vortical effects, that emerge in a helically-imbalanced rotating fermionic system. These phenomena lead to the appearance of a new gapless hydrodynamic excitation, the helical vortical wave. We also show that the presence of the helicity imbalance of quark matter increases the curvature of the QCD chiral pseudocritical line and shifts the critical endpoint towards lower temperatures and higher baryon chemical potentials. We demonstrate the existence of a thermodynamic duality between helical and vector (baryonic) chemical potentials. Finally, we argue that the enhancement in the spin polarization of anti-hyperons compared to the polarization of the hyperons in noncentral relativistic heavy-ion collisions arises as a result of an interplay between the chiral and helical vortical effects: we are able to describe the ratio of the (anti)hyperon spin polarizations, obtained by the STAR group, without fitting parameters.

Speaker: Prof. Maxim Chernodub (Université de Tours)
• 18:30
Heavy-ion physics: Interplay of statistical and field- theoretic approaches 30m

Heavy-ion physics: Interplay of statistical and field- theoretic approaches

Speaker: Prof. Valentin Zakharov (ITEP)
• 19:00
Massive gravity 30m
Speaker: Prof. Arkady Vainshtein (University of Minnesota)
• Massive gravity 30m
• 19:30 19:40
Break

Break

• 19:40 20:40
Discussion session 4
• 19:40
Discussion session (DL: Oleg Teryaev): Anomalous transport phenomena and related issues 1h
• Wednesday, 11 November
• 11:00 13:30
Session 5: Inhomogeneous phases in strongly interacting matter

Chairperson: Michael Buballa

• 11:00
Crystalline chiral condensates in dense quark matter 30m

I will give a brief review on studies of spatially modulated chiral condensates performed within effective low-energy models of QCD, discussing methods and some recent results on the possible phase structure of quark matter at finite baryon density.

Speaker: Dr Stefano Carignano (ICCUB)
• 11:30
Inhomogeneous chiral condensates within the Functional Renormalisation Group 30m

We investigate the stability of inhomogeneous chiral-symmetry breaking phases at non-vanishing chemical potential and temperature by applying the Functional Renormalization Group (FRG) to the two-flavor quark-meson model (QMM) in the chiral limit. The stability of inhomogeneous phases under quantum and thermal fluctuations beyond the mean-field approximation is an open question in the phase-diagram of low-energy effective models of QCD. We derived FRG flow equations for the QMM in local potential approximation with a specific one-dimensional inhomogeneous chiral condensate, the so called chiral density wave. These flow equations include fermionic and bosonic quantum fluctuations. In this talk we present, numerical results in a renormalization group consistent mean-field approximation, where we have solved the fermionic part of the afore-mentioned flow equations in a first step towards a complete numerical solution of the full flow equations.

Speaker: Mr Martin Jakob Steil (Technische Universität Darmstadt)
• 12:00
Inhomogeneous phases of the Gross-Neveu model with a finite number of flavors 30m

We present some recent results on inhomogeneous phases and baryons in the 1+1-dimensional Gross-Neveu model at finite temperature and finite chemical potential. It is known, that in the large $N_f$-limit the system shows an inhomogeneous condensate at low temperature and large chemical potential. We address the question whether a breaking of translation invariance is also seen for finite $N_f$, when quantum fluctuations are not suppressed. Results for $N_f=8$ and $N_f=2$ are presented. The simulation results indicate that many qualitative features of the solution for large $N_f$ are rediscovered for finite $N_f$. The talk is based on two recent works in collaroration with L. Panullo and M. Wagner from Frankfurt and with J. Lenz and B. Wellegehausen from Jena.

Speaker: Prof. Andreas Wipf (FS-University Jena)
• 12:30
Exploring the existence of inhomogeneous phases in the 2+1-dimensional Gross-Neveu model in the limit of infinitely many flavors 30m

We explore the existence of inhomogeneous phases in the 2+1-dimensional Gross-Neveu model in the limit of infinitely many flavors using a continuum approach as well as lattice field theory. At finite value of the regulator (momentum cutoff, lattice spacing) we find inhomogeneous phases. These phases disappear, however, when removing the regulator, i.e. when sending the momentum cutoff to infinity or the lattice spacing to zero.

Speaker: Prof. Marc Wagner and Dr. Kurth Lennart
• 13:00
Anomaly-induced inhomogeneous phase in QCD-like theories 30m

The ground state of QCD at nonzero baryon number chemical potential and in sufficiently strong magnetic fields is the Chiral Soliton Lattice: a topological phase carrying a crystalline condensate of neutral pions. The same is true for other QCD-like theories, including theories free from the sign problem. This disproves the long-standing conjecture that positivity of the determinant of the Dirac operator in a QCD-like theory implies the absence of inhomogeneous phases in its phase diagram.

Speaker: Prof. Tomas Brauner (University of Stavanger)
• 13:30 13:40
Break

Break

• 13:40 14:40
Discussion session 5
• 13:40
Discussion session (DL: Michael Buballa), Inhomogeneous phases in strongly interacting matter 1h
• 14:40 16:00
Break

Break

• 16:00 19:30
Session 6: QCD phase structure at non-zero baryon density

Chairperson: Gert Aarts

• 16:00
On the phase structure of QCD 30m

We map out the QCD phase structure with functional approaches. By now the results for the phase structure from these approaches also converge at large densities, including the location of the critical end point. We evaluate the remaining systematic errors and tasks, as well the the prospects.

Speaker: Prof. Jan M. Pawlowski (Heidelberg University)
• 16:30
The high density QCD phase diagram: of heavy ion collisions and neutron star mergers 30m

I will discuss the limits of current methods to calculate the equation of state of QCD matter at finite baryon density. All methods based on expanding lattice QCD results show to be limitred to $\mu_B/T<3$ a region where contributions from the net baryon density are negligible. Therefore I will show how it is possible to use constraints from astrophysical observations of neutron stars and their mergers, as well as observables from heavy ion collisions, to constrain the features of the QCD EoS at densities up to 10 times nuclear saturation density and Temperatures up to 200 MeV.

Speaker: Prof. Jan Steinheimer (Frankfurt Institute for Advanced Studies)
• 17:00
QCD Phase Diagrams with Charge and Isospin Axes under Heavy-Ion Collision and Stellar Conditions 30m

We investigate the phase transition from hadron to quark matter in the general case without the
assumption of chemical equilibrium. The effects of net strangeness on charge and isospin fractions,
chemical potentials, and temperature are studied in the context of the Chiral Mean Field (CMF)
model that incorporates chiral symmetry restoration and deconfinement. The extent to which
these quantities are probed during deconfinement in conditions expected to exist in protoneutron
stars, binary neutron-star mergers, and heavy-ion collisions is analyzed via the construction of 3-
dimensional phase diagrams.

Speaker: Prof. Veronica Dexheimer (Kent State University)
• 17:30
QCD phase diagram at non-zero real and imaginary chemical potential from lattice QCD 30m

We will show the continuum extrapolated results for all second order and some of the fourth order cumulants of net baryon-number, strangeness and electric charge fluctuations as well as their correlations obtained using the Highly Improved Staggered Quark (HISQ) action in (2+1)-flavour QCD by the HotQCD collaboration. We will show comparisons of our results with hadron resonance gas (HRG) model calculations and argue that the HRG model based description of strongly interacting matter works only upto the pseudo-crtical temperature of QCD. The cumulants of net charge fluctuations and their correlations at vanishing values of the charge chemical potentials ($\mu_{B,Q,S}=0$) provide the basis for Taylor expansions of various thermodynamic observables at non-zero values of the chemical potentials. We will use the updated results of HotQCD on higher order cumulants to constrain the location of a possible critical point in the QCD phase diagram.

We will also show a calculation of (2+1)-flavor QCD with an imaginary chemical potential with the aim to determine the critical quark mass at which the second order transition in the Roberge-Weiss plane turns into a first order transition. We use the Highly Improved Staggered Quark (HISQ) action and perform calculations in the Roberge-Weiss plane, where the value of the critical mass is expected to be largest. We explore a range of quark masses corresponding to pion mass values, $m_{\pi}$≥ 40 MeV. Contrary to calculations performed with unimproved actions we find no evidence for the occurrence of first order transitions at the small quark mass values explored so far.

Open Problems/discussions:
i) Resummation of Taylor series at small value of the non-zero baryon density?
ii) Interplay between RW transition and Chiral transition in the Chiral limit?

Ref: arXiv:2011.02812 [hep-lat]

Speaker: Dr Jishnu Goswami
• 18:00
QCD crossover line at finite chemical potential from the Lattice 30m

QCD crossover line at finite chemical potential from the Lattice
An efficient way to study the QCD phase diagram at small finite density
is to extrapolate thermodynamical observables from imaginary chemical potential.
The phase diagram features a crossover line starting from the
transition temperature already determined at zero chemical potential.
This talk focuses on the Taylor expansion of this line up to $\mu^4$ contributions. We present
the continuum extrapolation of the crossover temperature.

Speaker: Dr Jana Guenther (University of Regensburg)
• 18:30
Universality driven analytic structure of QCD crossover 30m

Recent lattice QCD calculations show strong indications that the chiral crossover of QCD at zero baryon chemical potential \mu_B is a remnant of the second-order chiral phase transition. Furthermore, the non-universal parameters needed to map temperature T and \mu_B to the universal properties of the second-order chiral phase transition have been determined recently. Motivated by these observations, first, we determine the analytic structure of the partition function -- the so-called Yang-Lee edge singularity -- in the QCD crossover regime, solely based on universal properties. Next, utilizing the lattice QCD results for non-universal parameters we map this singularity to the real T and complex \mu_B plane, leading to the determination of the radius of convergence in \mu_B in the QCD crossover regime. These universality- and QCD-based results provide tight constraints on the range of validity of the lattice QCD calculations at \mu_B>0. The implication of this result on the location of the conjectured QCD critical point is discussed.

Speakers: Prof. Vladimir Skokov (North Carolina State University / RBRC BNL), Gregory Johnson
• 19:00
Structure of the Lefschetz thimbles decomposition of lattice fermion models 30m

We discuss a framework for studying the properties of the Lefschetz
thimbles decomposition for lattice fermion models. Non-iterative
solver for the inversion of fermion determinants forms the core of the
method. It allows us to solve the gradient flow (GF) equations taking
into account the fermion determinant exactly. Being able to do so, we
can find both real and complex saddle points of the lattice action and
describe the structure of the Lefschetz thimbles decomposition for
large enough lattices to extrapolate our results to the thermodynamic
limit.
We show two possible applications of this technique. First of all, the
structure of the Lefschetz thimbles decomposition and to alleviate the
sign problem. The second application is systematic building of the
quasi-classical approximation taking into account Gaussian

Speaker: Dr Maksim Ulybyshev
• 19:30 19:40
Break

Break

• 19:40 20:40
Discussion session 6
• 19:40
Discussion session (DL: Gert Aarts), QCD phase structure at non-zero baryon density 1h
• Thursday, 12 November
• 10:00 12:30
Session 7: Effects of rotation in QCD phase diagram (NOTE! Early starting time)

Chairperson: Xu-Guang Huang

• 10:00
Rotating Relativistic Matter and Angular Momenta 30m

We will discuss the interplay between the magnetic field and the rotation. In the presence of the external magnetic field the angular momentum conservation in a highly nontrivial way. As a demonstration we will show the simplest example of magnetic vortices. If the whole frame is rotated, the boundary condition is crucial not to violate the causality bound, and in this sense, vortices are theoretically ideal objects that are regarded as localized vorticity. Then magnetic vortices are classified into (at least) three distinct classes according to the realization of angular momentum conservation. We also discuss a relation between spin conservation law and chiral anomaly, taking the simplest concrete example of U(1) gauge field.

Speaker: Prof. Kenji Fukushima (The University of Tokyo)
• 10:30
Chiral dynamics and gluodynamics under rotation 30m

We investigate the effect of rotation on chiral dynamics and gluodynamics
in the framework of NJL model and holography, respectively. We discuss the
effect of rotation on thermodynamical properties and phase structure.

Speaker: Prof. Mei Huang (University of Chinese Academy of Sciences(UCAS))
• 11:00
Rotational effect versus finite-size effect on chiral phase transition 30m

The rotational (or vortical) effect is one of the central topics in quark-hadron systems, such as heavy-ion collision and neutron stars. For the relativistic rotating matter, the most important fact would be that the thermodynamic limit is ill-defined because of the causality constraint. In this talk, we discuss how the finiteness of system-size affects the low-energy structure of rotating fermions. Taking into account the finite-size effect, we show that while the rotational effect cannot solely become physically visible, other external sources (temperature, density, background fields etc.) enable rotation to affect thermodynamic systems. As an example, we also demonstrate that the interplay between magnetic field and rotation changes the breaking structure of chiral symmetry; due to the rotational effect, chiral symmetry is restored as magnetic field increases, which we call the rotational magnetic inhibition.

Speaker: Dr Kazuya Mameda (RIKEN)
• 11:30
Rotation on lattices 30m

I give a introductory talk about rotation in lattice field theory. I overview the formulation and its problem in relativistic and non-relativistic theories.

Speaker: Prof. Arata Yamamoto
• 12:00
Lattice study of rotating gluodynamics 30m

In this report we present the results of lattice study of how rotation influences confinement/deconfinement transition in SU(3) gluodynamics. To conduct this study we pass to the reference frame which rotates with the system under consideration. In this reference frame rotation is accounted for by the external gravitational field. We calculate the Polyakov loop, its susceptibility and determine the critical temperature of the confinement/deconfinement transition for various angular velocities. We find that rotation leads to the rising of the critical temperature.

Speaker: Prof. Victor Braguta (MISIS, JINR)
• 12:30 12:40
Break

Break

• 12:40 13:40
Discussion session 7
• 12:40
Discussion session (DL: Xu-Guang Huang), Effects of rotation in QCD phase diagram 1h
• 13:40 14:30
Break

Break

• 14:30 17:00
Session 8: Non-zero isospin density and meson condensation

Chairperson: Gergely Endrődi

• 14:30
Chiral perturbation theory and pion condensation at finite isospin 30m

QCD at finite isospin is interesting for a number of reasons. One of them is that it is free of the sign problem and therefore amenable to lattice simulations.
In this talk, I will discuss recent results for two and three flavor chiral perturbation theory
at finite isospin. I will present results for the pressure, pion and quark condensates and isospin density. The results will be compared to those of recent lattice simulations.

Speaker: Prof. Jens Oluf Andersen (NTNU)
• 15:00
Meson condensation in chiral perturbation theory 30m

We discuss the properties of homogeneous and inhomogeneous meson condensates in the framework of chiral perturbation theory. We compare the results on the homogeneous pion condensate obtained in chiral perturbation theory with those of lattice QCD showing that there is good agreement for isospin chemical potentials up to about 2 m_\pi. Then, we turn to inhomogeneous phases, presenting the results obtained by a semi-analytical approach on solitonic-like structures.

Speaker: Prof. Massimo Mannarelli (INFN)
• 15:30
QCD thermodynamics at nonzero isospin asymmetry 30m

We study the thermodynamic properties of QCD at nonzero isospin chemical potential using improved staggered quarks at physical quark masses. In this talk, we will discuss the extraction of the equation of state and show results at zero and nonzero temperatures. As an application, we briefly discuss its relevance for the trajectory of the early Universe at nonzero lepton asymmetry.

Speaker: Dr Bastian Brandt (University of Bielefeld)
• 16:00
Finite Isospin Chiral Perturbation Theory in a Uniform Magnetic Field 30m

In this talk, I will discuss the zero-temperature phase diagram of finite isospin chiral perturbation theory in a uniform, external magnetic field. Since pions enter a superfluid state for chemical potentials larger than the pion mass and are electromagnetically charged, they become superconducting in the presence of a magnetic field. They exhibit type-II superconductivity and support stable magnetic vortices.

Speaker: Prof. Prabal Adhikari (St Olaf's College)
• 16:30
QCD phase structure in Polyakov linear-sigma model with non-zero isospin density 30m

In mean-field approximation, the Polyakov linear-sigma model (PLSM) with u-, d-, and s-quark flavors is utilized in analyzing the chiral condensates and the deconfinement order parameters, at non-zero isospin density. The results obtained on the bulk thermodynamics including pressure density, interaction measure, susceptibility and second-order correlations with baryon, strange and electric charge quantum numbers shall be confronted to the available lattice quantum chromodynamics (QCD) calculations. The excellent agreement encourage the study of QCD phase structure. We find that the pseudocritical temperatures Tχ decrease with the increase in isospin chemical potential and conclude that the QCD phase structure in (Tχ–μI) plane seems to extend the one in (Tχ–μB) plane, where μB is the baryon chemical potential.

Speaker: Prof. Abdel Nasser Tawfik (Nile University)
• 17:00 17:10
Break

Break

• 17:10 18:10
Discussion session 8
• 17:10
Discussion session (DL: Jens O. Andersen), Non-zero isospin density and meson condensation 1h
• 18:10 18:30
Break

Break

• 18:30 21:00
Session 9: Phase diagram in the context of heavy-ion collisions

Chairperson:

• 18:30
Transport properties of the hot and dense QGP 30m

We study the influence of the baryon chemical potential $\mu_B$ on the dynamical properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM)that is matched to reproduce the equation-of-state of the partonic system above the deconfinement
temperature Tc from lattice Quantum Chromodynamics (QCD).
We study the transport coefficients such as the ratio of the shear and bulk viscosities to the entropy density, i.e. $\eta/s$ and $\zeta/s$, the electric conductivity $\sigma_0/T$ as well as the baryon diffusion coefficient $\kappa_B$ and compare to related approaches from the literature(non-conformal holographic model, lattice QCD, NJL). We find that the ratios $\eta/s$ and $\zeta/s$ as well as $\sigma_0/T$ are in accord with the results from lattice QCD at $\mu_B$=0. Furthermore, we have considered the shear viscosity and the electric conductivity of strongly interacting quark matter within the extended Nf= 3 Polyakov Nambu-Jona-Lasinio (PNJL) model along with the crossover transition line for moderate values of baryon chemical potential 0≤$\mu_B$≤0.9 GeV as well as in the vicinity of the critical end point (CEP) and at large baryon chemical potential $\mu_B = 1.2$ GeV, where the first-order phase transition takes place.

We explore how the nature of the degrees-of-freedom affects the transport properties of the QGP. Moreover, we study the possible influence of the presence of a CEP and of a 1st order phase transition at high baryon chemical potential.
The out-of equilibrium study of the QGP is performed within the Parton–Hadron–String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections based on the DQPM and the evaluated at actual temperature T and baryon chemical potential $\mu_B$ in each individual space-time cell where partonic scattering takes place. The traces of their $\mu_B$ dependencies are investigated in different observables for symmetric Au + Au and asymmetric Cu + Au collisions such as rapidity and m_T-distributions and directed and elliptic flow coefficients v1, v2 in the energy range (s_NN)^(1/2) from 7.7 GeV to 200 GeV.

Speaker: Dr Olga Soloveva (Goethe University Frankfurt)
• 19:00
Probing the QCD equation of state with fluctuations of conserved charges 30m

Fluctuations of conserved charges carry rich information about the fine details of the QCD equation of state.
Recent lattice QCD data on high order baryon number susceptibilities are used here to constrain the excluded volume corrections in the hadron resonance gas model.
I will then address the question of comparison between experimental measurements of baryon and proton number fluctuations in heavy-ion collisions
and the corresponding grand-canonical thermal fluctuations from lattice QCD/excluded-volume HRG model, with a focus on effects of
global conservation laws, thermal smearing and difference between net proton and net baryon cumulants.

Speaker: Dr Volodymyr Vovchenko (Lawrence Berkeley National Laboratory)
• 19:30
Direct photon production in pp, pA and AA collisions 30m

We review experimental results on the direct and isolated photon production in pp, pA and AA collisions at different colliding energies and compare them with theoretical calculations. We discuss thermal direct photon production in AA collisions and consider several proposed solutions of “direct photon flow puzzle” - a strong measured collective flow of direct photons, comparable with the one of final hadrons and much stronger than predicted by hydrodynamic models.

Speaker: Dr Dmitri Peresunko (NRC "Kurchatov institute")
• 20:00
Probing chiral symmetry restoration with dileptons 30m

Finite baryon density induces a mixing between the vector and axial-vector states, and
yields multiple bumps and peaks around the vacuum masses of the $\rho, \omega$ and $\phi$ resonances in the spectral function. The modification become significantly pronounced when the mass difference between the parity partners decreases in dense matter.
We propose that the emergent enhancement in the dilepton production rates serves as an excellent
signature of the partially-restored chiral symmetry to be verified in heavy-ion collisions.

Speaker: Prof. Chihiro Sasaki (University of Wroclaw)
• 20:30
Transport model approach to Λ and Λ¯ polarization in heavy-ion collisions 30m

Thermal vorticity in non-central Au+Au collisions at energies 7.7≤s√≤62.4 GeV is calculated within the microscopic transport model UrQMD. The whole volume of an expanding fireball is subdivided into small cubic cells. Then we trace the final Λ and Λ¯ hyperons back to their last interaction point within a certain cell. Extracting the bulk parameters of hot and dense medium in the cell, one can get the temperature and the chemical potentials at the time of the hyperon emission by fitting the extracted characteristics to statistical model of ideal hadron gas. After that the polarization of both hyperons is calculated. We found that the polarization of both Λ and Λ¯ increases with decreasing energy of nuclear collisions. The stronger polarization of Λ¯ is explained (i) by slightly different freeze-out conditions of both hyperons and (ii) by the different space-time distributions of Λ and Λ¯.​

Speaker: Prof. Evgeny Zabrodin
• 21:00 21:10
Break

Break

• 21:10 22:10
Discussion session 9
• 21:10
Discussion session (DL: Elena Bratkovskaya) Phase diagram in the context of heavy-ion collisions 1h
• Friday, 13 November
• 10:00 12:30
Session 10: Theoretical ideas and experimental searches of the critical point (NOTE! Early starting time)

• 10:00
Search for the QCD Critical Point in Heavy-ion Collisions at RHIC 30m

Understanding the properties of quark matter and its phase structure can enhance our knowledge of universe evolution and the structure of visible matters. In the last two decades, many experimental evidences for the strongly interacting quark-gluon plasma (sQGP) have been observed in high energy heavy-ion collisions. Therefore, exploring the QCD phase structure at high baryon density, such as mapping the 1st order phase boundary and finding the QCD critical point, becomes one of the most important goals of the heavy-ion collisions. During 2010-2017, RHIC has finished the first phase of Beam Energy Scan program (BES-I), and STAR experiment has collected the data of Au+Au collisions at various collision energies from 200 to 7.7 GeV. To confirm the intriguing observations at BES-I, RHIC has started the second phase of beam energy scan program (BES-II) since 2018, focusing on the energies below 27 GeV. From 2018 to 2020, STAR experiment has taken the data of high statistics Au+Au collision at 9.2, 11.5, 14.6, 19.6 and 27 GeV (collider mode) and 3.0 - 7.7 GeV (fixed target mode). In this talk, I will discuss the experimental progress for exploring the QCD phase structure at RHIC-STAR experiment, especially focusing on the QCD critical point search. New facilities aiming for high baryon density region and future plan will be also discussed.

Speaker: Prof. Xiaofeng Luo (Central China Normal University)
• 10:30
Pre-clustering near the QCD critical point: nuclear correlations and light-nuclei production 30m

I will discuss some consequences of the proposed modification of the nuclear force due to the QCD critical end point (CEP). A simple model for the internucleon potential close to the CEP suggests that attraction among nucleons is likely to dominate over repulsion. The net effect would result in sizable nuclear correlations, and the possible formation of pre-clusters of nucleons. In this scenario one can expect an eventual overproduction of light nuclei compared to thermal expectations. I will describe how certain light-nuclei yield ratios, in particular those involving Helium 4, can be used to test these effects in heavy-ion collisions, and the presence of the CEP.

Speaker: Dr Juan Torres-Rincon
• 11:00
Status of the NICA project 30m

The global scientific goal of the NICA/MPD (Nuclotron-based Ion Collider fAcility / Multy Purpose
Detector) project realizing at JINR is to explore the phase diagram of strongly interacting matter in the
region of high compression. The proposed program allows to search for possible signs of the phase
transitions and critical phenomena in heavy ion (up to Au) collisions at centre-of-mass energies up to
11 GeV/u. The collider experiment provides optimum conditions for efficient measurements at energy
scan. Main accelerator of the NICA complex is the Nuclotron – 251.52 m long superconducting ion
synchrotron equipped with two injection chains: for heavy (including small superconducting synchrotron
– the Booster) and for light ions. The collider experiments will be provided at two storage rings with two
interaction points based on double-aperture (top-to-bottom) superconducting magnets. For the
moment, the modernization of the Nuclotron light ion injection chain was provided. New linear
accelerator of the heavy ion injection chain was constructed and commissioned in 2016. All
superconducting magnets for the Booster were fabricated at JINR, the Booster assembly is completed.
Assembly of the MPD has been started in 2020, production of the collider systems is in progress.
Completion of the collider assembly is scheduled for 2022.

Speaker: Dr Anatoly Sidorin (JINR, Dubna, Russia)
• 11:30
Experimental study of QCD phase diagram at NICA energy range 30m

A short overview is presented on the recent experimental studies of the QCD phase diagram at low collision energy range $\sqrt{s} \le 11$ GeV, covered in the future by NICA collider. It also considered some physics analyses which are feasible with the first stage of MPD detector and proposed new ones which may give a new way of looking at possible QCD phase transition at NICA energy range

Speaker: Dr Oleg Rogachevsky (Joint Institute for Nuclear Research (RU))
• 12:00
Phase diagram of strongly interacting matter and how should we study it in heavy ion collisions 30m

After almost 40 years of experiments on heavy ion collisions (HIC) the situation with the discovery the new phases of QCD is somewhat paradoxic. On the one hand, we are sure that at highest RHIC energies the partons are created in HIC, but on the other hand, we do not know the answers to three principal questions:
1. At high baryonic charge densities the chiral symmetry restoration and color deconfinement are the same phenomenon or not?
2. At high baryonic charge densities
the chiral symmetry restoration and color deconfinement
are phase transitions or not?
3. What are the collision energy thresholds for these phenomena?

The new experiments on RHIC and the ones planned on the NICA and FAIR will provide us with a lot of experimental data, but, unfortunately, there are strong arguments that with the existing theoretical knowhow it will be impossible to convince ourselves and the colleagues from the other communities that we have clear answers on these principal questions. The problem is not only that we are dealing with small and short living systems in which there are no phase transitions or (tri)critical endpoint in a strict sense of statistical mechanics. The main problem, in my mind, is that our best theoretical tools to model phase transitions, namely the equations of state and the hydrodynamic codes, are not suited to model those small and short living systems. Based on the morphological thermodynamics [1] and its quantum version [2] I argue that it is absolutely necessary to develop the finite volume statistical models for the phase of chiral hadrons, for quark gluon plasma and phase transformations between them.
The best starting point would be exactly solvable models
similar to the quark gluon bags with surface tension [3] which, besides the surface tension coefficient, should also include the curvature tension coefficient (a kind of Tolman correction) and large width of quark gluon plasma bags in spirit of Ref. [4]. Such modifications are necessary, but to develop the realistic equations of state of all QCD phases the input from the lattice formulation of QCD, from the Nambu-Jona-Lasinio model (surface tension) and from the generalized functional renormalization group approach (in-medium width) [5] is of high demand. In addition, it seems that without developing the hydro-kinetic approach for the imaginary values of free energy to treat the metastable states in finite systems. Finally, I will argue that to resolve those principal problems we need to create a theoretical collaboration whose members will concentrate their efforts not on the current fashion(s), but on solving those principal problems.

References:
[1].P-M. Koenig, R. Roth and K.R. Mecke, Phys. Rev. Lett. 93, 160601 (2004).
[ 2 ]. K.A. Bugaev, Eur. Phys. J. A 55: 215, 1-7 (2019).
[ 3 ]. K.A. Bugaev and P.T. Reuter, Ukr. J. Phys. 52, 489-510 (2007).
[ 4 ]. K.A. Bugaev, V.K. Petrov and G.M. Zinovjev, Phys. Rev. C 79, 054913 (2009)
[5]. F. Gao and J.M. Pawlowski, Phys. Rev. D 102, 034027 (2020).

Speakers: Prof. Kyrill Bugaev (Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine), Dr Oleksii Ivanytskyi (BITP)
• 12:30 12:40
Break

Break

• 12:40 13:40
Discussion session 10
• 12:40
Discussion session (DL: Kyrill Bugaev): "Theoretical ideas and experimental searches of the critical point" 1h
• 13:40 13:50
• 13:50 14:00
Break

Break

• 14:00 17:00
Session 11: Heavy quarks

• 14:00
Properties of doubly heavy baryons 30m

The two heavy quark combinations cc, bb and bc unifies with s quark in case of three doubly heavy $\Omega$ baryons, while for six doubly heavy Ξ baryons light quarks u or d are combined. The ground, radial, and orbital states are calculated in the framework of the hypercentral constituent quark model with Coulomb plus linear potential. The different approaches and their predicted masses of these heavy baryons are mentioned and compared, thus, the average possible range of excited states masses of these baryons can be determined. Recently, the LHCb collaboration reported the mass of $\Xi_{cc}^{++}$ as a ground state. The Regge trajectory is constructed in both the (n, $M^2$) and the (J, $M^2$) planes for all doubly heavy baryons and their slopes and intercepts are also determined. Magnetic moments and decay properties of doubly heavy baryons are also discussed.

Speaker: Dr Zalak Shah (SVNIT,SURAT)
• 14:30
The doubly heavy particles: baryons, tetraquarks and pentaquarks 30m

In this talk, I will review some new theoretical and experimental developments on doubly heavy baryons as well as tetraquarks and pentaquarks made of double heavy quarks, by insisting on our recent studies. I will compare the predictions of the phenomenological models with the experimental data on some parameters of the hadronic states under discussion. I will also discuss different assignments on the structure and quantum numbers of the recently discovered doubly heavy particles at hadron colliders.

Speaker: Prof. Kazem Azizi (University of Tehran & Dogus University)
• 15:00
Towards the understanding of quarkonium production through global-fit analyses of LHC data 30m

Hadron formation is one of the most interesting open problems within the context of QCD. Understanding how the quarks bind with each other implies combining complex analytical perturbative calculations with not-yet-understood non-perturbative aspects. Quarkonia are the simplest quark-antiquark bound states and provide an ideal window to probe hadron formation. The high quality quarkonium production (cross sections and polarizations) measurements reported by the LHC experiments, when studied with state-of-the-art data-driven analysis methods, allow us to perform a significant step forward in our understanding of the mechanisms at the basis of quarkonium formation. In this talk we will present results from a series of global-fit analyses of cross section and polarization measurements performed by the ATLAS and CMS experiments using large samples of pp collisions at 7, 8 and 13 TeV, including comparisons between model-independent phenomenological scenarios and the more complex NRQCD approach.

Speaker: Dr Mariana Araújo (LIP-CMS)
• 15:30
The fate of quarkonia in heavy-ion collisions at LHC energies: a unified description of the sequential suppression patterns 30m

Measurements made at the LHC have shown that the production of the J/psi, psi(2S), Upsilon(1S) and Upsilon(2S) quarkonia is suppressed in Pb–Pb collisions, with respect to the extrapolation of the pp production yields. The psi(2S) and Upsilon(2S) states are more strongly suppressed than the ground states and the level of the suppression changes with the centrality of the collision.

We show that the measured patterns can be reproduced by a simple model, where all quarkonia are treated in a unified way, starting from the recent realisation that, in pp collisions, the probability of quarkonium formation has a universal dependence on the binding-energy of the bound state. The hot-medium suppression effect is parametrized by a penalty factor in the binding energy, identical for all (S- and P-wave) charmonium and bottomonium states, including those that indirectly contribute to the measured results through feed-down decays. This single parameter, computed through a global fit of all available suppression patterns, fully determines the hierarchy of nuclear effects, for all states and centrality bins.

The resulting faithful description of the data provides convincing evidence in favour of the conjecture of sequential quarkonium suppression induced by QGP formation.

Speaker: Dr Pietro Faccioli (LIP)
• 16:00
Heavy Quarkonium Production in pNRQCD 30m

We compute the color singlet and color octet NRQCD long-distance matrix elements for inclusive production of P-wave quarkonia in the framework of potential nonrelativistic QCD. In this way, the color octet NRQCD long-distance matrix element can be determined without relying on measured cross section data, which has not been possible so far. We obtain inclusive cross sections of χcJ and χbJ at the LHC, which are in good agreement with data. In principle, the formalism developed in this work can be applied to all inclusive production processes of heavy quarkonia.

Speaker: Dr Hee Sok Chung (Technical University of Munich)
• 16:30
Fully-heavy tetraquark states and their strong decays into di-charmonia 30m

In this talk, I will introduce our investigations on the fully-heavy tetraquark states, including the calculations of their mass spectra and their strong decays into di-charmonia. Our calculations of the masses for the fully-heavy tetra quarks have been done several years before the recent LHCb's observation in the di-$J/\psi$ structure. However, our results suggest that the broad structure around 6.2-6.8 GeV in LHCb's observation can be interpreted as an S-wave $cc\bar c\bar c$ tetraquark with $J^{PC}=0^{++}$ or $2^{++}$, and the narrow structure around 6.9 GeV can be interpreted as a P-wave one with $J^{PC}=0^{-+}$ or $1^{-+}$. These conclusions are also confirmed by our recent study of the strong decays of the fully-charm tetraquarks into di-charmonia, in which we consider all possible two-body strong decays for these tetrequarks and calculate their relative branching ratios through the Fierz rearrangement.

Speaker: Prof. Wei Chen (Sun Yat-Sen University)
• 17:00 18:00
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• 18:00 19:30
Session 11: Heavy quarks

• 18:00
Transport and spectral properties of heavy quarks from lattice QCD 30m

In this talk I will review our recent lattice results on the charmonia & bottomonia spectral functions and heavy-quark transport properties in hot medium. The spectral analyses are performed on the quarkonium correlators measured on the lattice extrapolated to the continuum limit and interpolated to physical $J/\psi$ and $\Upsilon$ masses. Good agreement is observed between our lattice data and the perturbation spectral functions. We also study the transport properties of heavy quarks via color-electric correlators measured under gradient flow. With this newly developed method we achieved good signal in the data and a non-perturbative renormalization for the correlators. Our studies give consistent results with those from other lattice studies. In the end I will give an outlook for the future work that can be done and the possible difficulties that we could meet.

Speaker: Dr Hai-Tao Shu (Bielefeld University)
• 18:30
Heavy tetraquarks in the relativistic quark model 30m

We give a review of the calculations of the masses of tetraquarks with two and four heavy quarks in the framework of the relativistic diquark-antidiquark model based on the quasipotential approach. Quasipotentials of quark-quark and diquark-antidiquark interactions are constructed similarly to previous studies of mesons and baryons. All parameters of the model were fixed by meson and baryon properties. Diquarks are considered in the color triplet state and it is assumed that they interact as a whole. The internal structure of diquarks is taken into account by the calculated form factor of the diquark-gluon interaction. Theoretical predictions are compared with the available experimental data. It is argued that the structures in the di-$J/\psi$ mass spectrum observed recently by the LHCb Collaboration can be interpreted as $cc\bar c\bar c$ tetraquarks.

• 19:00
Bottomonia production and polarization in the NRQCD with kt-factorization 30m

The $\Upsilon(nS)$ production and polarization at high energies is studied in the framework of $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The direct production mechanism and feed-down contributions from radiative $\chi_b(mP)$ decays are taken into account. The transverse momentum dependent gluon densities in a proton were derived from the Ciafaloni–Catani–Fiorani–Marchesini evolution equation and Kimber-Martin-Ryskin prescription. Treating the non-perturbative color octet transitions in terms of the mulitpole radiation theory, we extract the corresponding non-perturbative matrix elements for $\Upsilon(nS)$ and $\chi_b(mP)$ mesons from a combined fit to $\Upsilon(nS)$ transverse momenta distributions measured by the CMS and ATLAS Collaborations at the LHC energies $\sqrt{s}=7$ and $13$ TeV and from the relative production rate $R^{\chi_b(nP)}_{\Upsilon(nS)}$ measured by the LHCb Collaboration at $\sqrt{s}=7$ and $8$ TeV. Then we apply the extracted values to investigate the polarization parameters $\lambda_\theta$, $\lambda_\phi$ and $\lambda_{\theta\phi}$, which determine the $\Upsilon(nS)$ spin density matrix. Our predictions have a good agreement with the currently available data within the theoretical and experimental uncertainties.

Speaker: Mr Nizami Abdulov (Lomonosov Moscow State University)
• 19:30 20:00
Break

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• 20:00 22:30
Session 11: Heavy quarks

• 20:00
Exotic hadrons from functional methods 30m
Speaker: Prof. Christian Fischer ( Institut für Theoretische Physik Universität Gießen)
• 20:30
Production of X(3872) at High Multiplicity 30m

The LHCb collaboration has observed a decrease with multiplicity of the ratio of the prompt production rates of $X(3872)$ and $\psi(2S)$ in pp collisions. We show that this observation can be explained by the scattering of comoving pions from $X(3872)$ if it is a weakly bound charm-meson molecule.

Speaker: Prof. Eric Braaten (...)
• 21:00
Bottomonium suppression and elliptic flow from real-time quantum evolution 30m

We compute the suppression and elliptic flow of bottomonium using real-time solutions to the Schroedinger equation with a realistic in-medium complex-valued potential. To model the initial production, we assume that, in the limit of heavy quark masses, the wave-function can be described by a lattice-smeared (Gaussian) Dirac delta wave-function. The resulting final-state quantum-mechanical overlaps provide the survival probability of all bottomonium eigenstates. Our results are in good agreement with available data for $R_{AA}$ as a function of $N_{\rm part}$ and $p_T$ collected at $\sqrt{s_{\rm NN}} =$ 5.02 TeV. In the case of $v_2$ for the various states, we find that the path-length dependence of $\Upsilon(1s)$ suppression results in quite small $v_2$ for $\Upsilon(1s)$. Our prediction for the integrated elliptic flow for $\Upsilon(1s)$ in the $10{-}90$\% centrality class is $v_2[\Upsilon(1s)] = 0.0026 \pm 0.0007$. We additionally find that, due to their increased suppression, excited bottomonium states have a larger elliptic flow and we make predictions for $v_2[\Upsilon(2s)]$ and $v_2[\Upsilon(3s)]$ as a function of centrality and transverse momentum. Similar to prior studies, we find that it is possible for bottomonium states to have negative $v_2$ at low transverse momentum.

Speaker: Prof. Michael Strickland (Kent State University)
• 21:30
Bottomonium properties at high temperatures from lattice NRQCD 30m

I will discuss the properties of $\Upsilon(nS)$ bottomonium states as well as the properties of $\chi_b(nS)$ bottomonium states at non-zero temperature using lattice NRQCD. In this study $48^3 \times 12$ lattices are used with highly improved staggered quark (HISQ) action with physical strange quark and light quark masses corresponding to the pion mass of 160 MeV in the continuum limit. Furthermore, extended quarkonium operators have been used in the analysis ensuring a relatively simple form of the resulting spectral function. We find that bottomonium states have a large thermal width at high temperatures, which is proportional to the temperature. We also observe a sequential pattern of the thermal width, i.e. higher excited states, which are larger in size, have a larger thermal width. We do not see indications for a significant thermal mass shift of bottomonium states. In addition we study the Bethe-Salpeter amplitudes of S-wave bottomonia at zero and finite temperature on the lattice within NRQCD. The above results are based on the following papers:
[1] R. Larsen, S. Meinel, S. Mukherjee, P. Petreczky, Phys. Rev. D 100 (2019) 074506
[2] R. Larsen, S. Meinel, S. Mukherjee, P. Petreczky, Phys. Lett. B 800 (2020) 135119
[3] R. Larsen, S. Meinel, S. Mukherjee, P. Petreczky, e-Print:2008.00100 [hep-lat]

Speaker: Prof. Peter Petreczky (BNL)
• 22:00
Doubly Heavy Baryons: Lifetimes and Branching fractions of the Weak Decays 30m
Speaker: Dr Alexey Luchinsky
• 22:30 22:40
Break

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• 22:40 23:40
Discussion session 11
• 22:40
Discussion session (DL: Carlos Lourenco and Alexey Luchinsky) "Heavy quarks"" 1h