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10th Asian Triangle Heavy-Ion Conference - ATHIC 2025
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Asia/Kolkata
Mayfair Palm Beach Resort, Gopalpur-On-Sea, Berhampur, Odisha
Description
The 10th Asian Triangle Heavy-Ion Conference (ATHIC 2025) will be organized by the Indian Institute of Science Education and Research Berhampur. The conference will be held in Mayfair Palm Beach Resort, Gopalpur-On-Sea, Berhampur, Odisha, India from Monday, the 13th of January 2025 through Thursday, the 16th of January, 2025. The event will be in physical mode only with no remote participation or broadcasting arrangements.
ATHIC 2025 inherits the tradition of the previous conferences held first in Seoul in 2006 while the latest was held in Hiroshima in 2023. Many physicists from Asian countries have been actively working on both experimental and theoretical sides of heavy-ion collisions. ATHIC brings them together to discuss various exciting aspects of this field. We hope to have fruitful discussions among the participants and develop new ideas to press us forward in further understanding of hot and dense QCD matter.
ATHIC 2025 will focus on topics including, but not limited to:
- QCD Phase Diagram, criticality and fluctuations
- Initial State - pre-equilibrium dynamics, baryon stopping, intense electromagnetic field
- Hard probes - jets and electromagnetic probes, heavy flavor, quarkonia
- Collective dynamics - conserved charges, spin, vorticity, freezeout, afterburner
- Baryon rich QCD matter, nuclear astrophysics
- Collectivity in small systems
- Physics opportunities at the Future Electron Ion Collider and the RHIC Spin program
- New theoretical developments
- Future experimental programs
The conference proceedings will be published online by the Journal of Subatomic Particles and Cosmology (JSPC), Elsevier. Further, JSPC will award the following prizes:
Best Oral Presentations (Experiment):
1st Prize: Award Certificate + 150 €
2nd Prize: Award Certificate + 100 €
Best Oral Presentations (Theory):
1st Prize: Award Certificate + 150 €
2nd Prize: Award Certificate + 100 €
Important Note 1: For registration, a CERN account is required. If you do not have one, a CERN lightweight account can be created at
https://account.cern.ch/account/Externals/RegisterAccount.aspx
Important Note 2: We might be able to provide some financial support in terms of waived registration fees and accommodation to early-career participants (Masters student/Ph.D student./Postdoc only). You can apply for support during registration at
https://indico.cern.ch/event/1424442/registrations/106993/
Organisers
Contact
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8:30 AM
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9:00 AM
Registration
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9:00 AM
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9:30 AM
Inauguration / Welcome Mayfair
Mayfair
Main Hall -
9:30 AM
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9:40 AM
Group Photo
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9:40 AM
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10:05 AM
Coffee / Tea Break
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10:05 AM
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12:35 PM
Plenary
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10:05 AM
Overview of current status 25m
Overview of current status
Speaker: Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN)) -
10:30 AM
Recent results from lattice QCD on the phase diagram 25m
Recent results from lattice QCD on the phase diagram
Speaker: Jishnu Goswami (Bielefeld University) -
10:55 AM
Studying the QCD phase diagram via fluctuations 25m
Studying the QCD phase diagram via fluctuations
Speaker: Maneesha Sushama Pradeep -
11:20 AM
Experimental Status of QCD Phase Diagram 25m
Experimental Status of QCD Phase Diagram
Speaker: Ashish Pandav -
11:45 AM
Out of equilibrium physics in the vicinity of the QCD critical point and in the initial state 25m
Out of equilibrium physics in the vicinity of the QCD critical point and in the initial state
Speaker: Chandrodoy Chattopadhyay (North Carolina State University) -
12:10 PM
Unveiling Initial State Fluctuations Using $[p_{\mathrm{T}}]$ Cumulants With ATLAS 25m
The event-by-event variations in the initial conditions and subsequent expansion of the Quark-Gluon Plasma (QGP) directly affects the distribution of the event-averaged transverse momentum ($[p_{\mathrm{T}}]$) of particles. Typically, the contributions to the transverse momentum from radial flow velocity and thermal components are extracted using simultaneous Blast-Wave fits to $p_{\mathrm{T}}$ spectra of identified hadrons. However, disentangling these contributions on an event-by-event basis arising from fluctuations in the overlap area (“Geometrical component”) from all other sources at fixed geometry (“Intrinsic component”) remains a challenge.
In this talk, I will present new, precise ATLAS measurements of $[ p_\mathrm{T}]$ cumulants up to third order in heavy-ion collisions as a new tool to disentangle Geometric and Intrinsic fluctuations. The observables exhibit distinct behavior, particularly in ultra-central collisions where geometrical variations are suppressed as the overlap area reaches its maximum. These measurements provide the first experimental means to disentangle different sources of fluctuations arising from the initial state and medium evolution, offering new constraints on key properties of the QGP, such as the speed of sound.Speaker: Somadutta Bhatta (Stony Brook University (US))
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10:05 AM
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12:35 PM
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1:50 PM
Lunch
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1:50 PM
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3:30 PM
Plenary
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1:50 PM
The physics of strong electromagnetic fields in heavy ion collisions 25m
The physics of strong electromagnetic fields in heavy ion collisions
Speaker: Koichi Hattori (Zhejiang University) -
2:15 PM
Relativistic resistive magnetohydrodynamic framework to study heavy ion collisions 25m
Relativistic resistive magnetohydrodynamic framework to study heavy ion collisions
Speaker: Chiho Nonaka -
2:40 PM
Results on magnetohydrodynamics simulations with BHAC-QGP 25m
Results on magnetohydrodynamics simulations with BHAC-QGP
Speaker: Ashutosh Dash -
3:05 PM
Chiral instabilities in relativistic heavy ion collisions 25m
Chiral instabilities in relativistic heavy ion collisions
Speaker: Sayantan Sharma (IMSc)
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1:50 PM
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3:30 PM
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4:15 PM
Coffee / Tea Break
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4:15 PM
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6:20 PM
Plenary
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4:15 PM
Physics of high baryonic matter 25m
Physics of high baryonic matter
Speaker: Nu Xu -
4:40 PM
Some recent theoretical advances in studying dense QCD phase transition 25m
Some recent theoretical advances in studying dense QCD phase transition
Speaker: Srimoyee Sen -
5:05 PM
Indian contribution to build FAIR at GSI 25m
Indian contribution to build FAIR at GSI
Speaker: Saikat Biswas (Bose Institute (IN)) -
5:30 PM
Overview of neutron stars and their connection to QCD phase diagram 25m
Overview of neutron stars and their connection to QCD phase diagram
Speaker: Rana Nandi -
5:55 PM
Observational constraints on the properties of the neutron star matter 25m
Observational constraints on the properties of the neutron star matter
Speaker: Tuhin Malik (CFisUC, Department of Physics, University of Coimbra, 3004-516 Coimbra, Portugal)
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4:15 PM
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8:30 AM
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9:00 AM
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9:00 AM
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10:40 AM
Plenary Main Hall
Main Hall
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9:00 AM
Electron Ion Collider (EIC) - Theory perspective : Spin Physics 25m
In this talk I'll give an overview of the theory opportunities
related to QCD spin physics provided by the upcoming EIC.Speaker: Asmita Mukherjee -
9:25 AM
Physics opportunities at the EIC 25m
Physics opportunities at the EIC
Speaker: Satoshi Yano (Hiroshima University (JP)) -
9:50 AM
EIC physics: Recent theoretical advances from the BLFQ collaboration 25m
EIC physics: Recent theoretical advances from the BLFQ collaboration
Speaker: Xingbo Zhao -
10:15 AM
Indian participation in ePIC at EIC 25m
Indian participation in ePIC at EIC
Speaker: Lokesh Kumar (Panjab University (IN))
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9:00 AM
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10:40 AM
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11:00 AM
Coffee / Tea Break
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11:00 AM
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12:50 PM
Plenary
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11:00 AM
Collectivity with system size 25m
Collectivity with system size
Speaker: Sushanta Tripathy (CERN) -
11:25 AM
Light flavor resonance production in heavy ion collisions 25m
Light flavor resonance production in heavy ion collisions
Speaker: Sadhana Dash (IIT- Indian Institute of Technology (IN)) -
11:50 AM
Electromagnetic probes of QGP 25m
Electromagnetic radiation, from both photons and dileptons, serves as exceptional probes of the evolution of relativistic heavy-ion collisions as unlike hadronic particles, these are produced throughout the evolution of the collision and escape the medium unmodified, providing direct information about the early and hot stages of the system. Photons primarily originate from initial hard scatterings, thermal radiation from the QGP, and interactions in the hadronic phase, while dileptons offer a mass-dependent view of the thermal properties of the medium. Recent experimental efforts, combined with advancements in theoretical models, have improved our understanding of electromagnetic radiation as a sensitive tool for probing the QGP. In addition to the measurements of dilepton mass distributions, and the direct photon momentum spectra for small and large collision systems, in this talk, azimuthal anisotropies of direct photons in relativistic heavy-ion collisions will be presented, thereby shedding light on the long-standing direct photon puzzle.
Speaker: Roli Esha (Center for Frontiers in Nuclear Science, Stony Brook University) -
12:15 PM
Experimental overview on recent measurements of resonances and exotics 25m
Experimental overview on recent measurements of resonances and exotics
Speaker: Junlee Kim (CERN) - 12:40 PM
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11:00 AM
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12:50 PM
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2:10 PM
Lunch
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2:10 PM
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4:15 PM
Plenary
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2:10 PM
Heavy flavor on lattice 25m
Heavy flavor on lattice
Speaker: Dibyendu Bala (Bielefeld University) -
2:35 PM
Experimental overview on the open heavy flavor measurement in relativistic heavy ion collisions 25m
Experimental overview on the open heavy flavor measurement in relativistic heavy ion collisions
Speaker: Min Jung Kweon (Inha University (KR)) -
3:00 PM
Recent developments in charm phenomenology 25m
Recent developments in charm phenomenology
Speaker: Mayank Singh (Vanderbilt University) -
3:25 PM
Quarkonium measurements in relativistic heavy ion collisions 25m
Quarkonium measurements in relativistic heavy ion collisions
Speaker: Zebo Tang (University of Science and Technology of China) -
3:50 PM
Physics at sPHENIX 25m
Physics at sPHENIX
Speaker: Maya Shimomura (Nara Women's University)
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2:10 PM
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4:15 PM
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4:35 PM
Coffee / Tea Break
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4:35 PM
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7:05 PM
Plenary
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4:35 PM
Experimental overview of recent jet measurements in relativistic heavy ion collisions 25m
Experimental overview of recent jet measurements in relativistic heavy ion collisions
Speaker: NIHAR RANJAN Sahoo (Texas A&M University) -
5:00 PM
Jets in relativistic heavy ion collisions: Theory perspective 25m
Jets in relativistic heavy ion collisions: Theory perspective
Speaker: Varun Vaidya -
5:25 PM
Jet shape measurements in relativistic heavy ion collisions 25m
Jet shape measurements in relativistic heavy ion collisions
Speaker: Saehanseul Oh (Sejong University) -
5:50 PM
Drell Yan as a probe of the nucleus 25m
Drell Yan as a probe of the nucleus
Speaker: Hyunchul Kim (Chonnam National University (KR)) -
6:15 PM
Observation of the Antimatter Hypernucleus 25m
Matter-antimatter asymmetry is a research topic of fundamental interest, as it is the basis for the existence of the matter world, which survived annihilation with antimatter in the early Universe.
High energy nuclear collisions create conditions similar to the Universe microseconds after the Big Bang, with comparable amounts of matter and antimatter.
Much of the antimatter created escapes the rapidly expanding fireball without annihilation, making such collisions an effective experimental tool to create heavy antimatter nuclear objects and study their properties.In this presentation, we give a brief review of the history of antimatter hypernuclear research, then we report the first discovery of the heaviest antimatter particle ($^4_{\bar{\Lambda}}\overline{\hbox{H}}$) ever seen on Earth, composed of an anti-Lambda ($\bar{\Lambda}$), an antiproton and two antineutrons.
$^4_{\bar{\Lambda}}\overline{\hbox{H}}$ is reconstructed through its two-body decay in ultrarelativistic heavy ion collisions at the STAR experiment at the Relativistic Heavy Ion Collider.A total of about 6.4 billion U+U, Au+Au, Ru+Ru, and Zr+Zr collision events with center-of-mass energy per colliding nucleon-nucleon pair $\sqrt{s_{NN}}$=193GeV (U+U) or 200GeV (other systems) are used in this analysis.
The measurement of antihypernuclei $^4_{\bar{\Lambda}}\overline{\hbox{H}}$ lifetime is achieved for the first time and compared with lifetime of their corresponding hypernuclei $^4_{\Lambda}\hbox{H}$ , which allows for further tests of the CPT symmetry.
Production yield ratios among (anti)hypernuclei and (anti)nuclei are also measured and compared with theoretical model predictions, shedding light on their production mechanism.Speaker: Junlin Wu (University of Chinese Academy of Sciences) -
6:40 PM
Search for baryon junction 25m
Search for baryon junction
Speaker: Zhangbu Xu (Kent State University)
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4:35 PM
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7:30 PM
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9:45 PM
Conference Dinner
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9:00 AM
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10:40 AM
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9:00 AM
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10:40 AM
Parallel A: Initial State Chair: Chiho Nonaka
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9:00 AM
Constraint on initial conditions from nonlinear causality 18m
Relativistic hydrodynamics has played a vital role in understanding the bulk and the transport properties of the deconfined nuclear matter, the quark gluon plasma, created in high-energy nuclear collision. It is often supposed that the local equilibrium is reached rapidly after the collisions and that the created matter starts to behave as a fluid with small viscous effects subsequently. It is, however, not at all trivial from which stage just after the collision the fluid picture can be applied to the system. In this study, we address this issue from a point of view of nonlinear causality.
In a recent study, necessary and sufficient conditions have been obtained for the system to be causal from the analysis of characteristic velocity of nonlinear relativistic dissipative hydrodynamic equations [1]. By analyzing numerical solutions of hydrodynamic equations from these conditions, it turned out that the causality is likely to be violated in the early stage [2]. This strongly suggests that the violation of causality occurs when the system is away from the local equilibrium.
In this study, we employ a one-dimensional expanding system [3], establish a relation between a degree of nonequilibrium and violation of causality and scrutinize whether solutions for given initial conditions obey causality. We find the inverse Reynolds number, which is a measure of nonequilibrium, is highly constrained from nonlinear causality. We also demonstrate how the solution violates or obeys the causality in a one-dimensional expanding system. We also obtain the minimum initial proper time allowed from the nonlinear causality and the observed transverse energy at RHIC and LHC. This sheds light on understanding the initial stages in high-energy nuclear collisions.
[1] F.S. Bemfica et al., Phys. Rev. Lett. 126, 222301 (2021).
[2] C. Plumberg et al., Phys. Rev. C 105, 061901 (2022).
[3] J.D. Bjorken, Phys. Rev. D 27, 140 (1983).Speaker: Tetsufumi Hirano (Sophia Univ.) -
9:18 AM
Neural network study of the impact of nuclear structures in heavy ion collisions 13m
Understanding the nuclear structure in heavy-ion collisions is essential, as it critically influences final state observables. However, characterizing the structure of heavy nuclei in high-energy collisions remains challenging. Current simulation methods for modeling final state events based on initial state data are highly reliant on model parameters, requiring extensive tuning and adjustment. To simplify nuclear structure estimation and minimize model parameter dependencies, we propose a novel approach of using a state-of-the-art neural network architecture that maps final state observables directly with initial nuclear structure characteristics. We train this model with $^{238}U+^{238}U$ ($\sqrt{s_{NN}}=193$ GeV) and $^{129}Xe+^{129}Xe$ ($\sqrt{s_{NN}}=5.44$ TeV) collision data to ensure model robustness across system sizes and collision energies. This allows us to extract quantitative information on nuclear deformation from event-by-event correlations of final state observables, effectively minimizing parameter influence. Our study leverages various three-particle and four-particle correlations, alongside their combinations, to train the models, analyze error distribution patterns, and identify the most effective observables for accurate and precise nuclear deformation estimation. We found that prediction accuracy strongly depends on the type of nuclear deformation used to train the models, with accuracy ranging from $90\%-100\%$, depending on the specific deformation parameters. The results also reveal that flow-transverse momentum correlation plays the leading role. The method developed in this study aims to advance our understanding of the initial state in heavy-ion collisions, potentially providing a robust framework for probing nuclear structures with reduced computational constraints.
Speaker: Mr Abhisek Saha (Peking University) -
9:31 AM
Study of first-order event plane correlated anisotropic flow in heavy-ion collisions at high baryon density region 13m
Anisotropic flow parameters $(v_{n})$ are important observables as they provide insight into the collective expansion and transport properties of the medium produced in relativistic heavy-ion collisions. Among these parameters, directed flow ($v_1$) describes the collective sideward motion of produced particles in heavy-ion collisions. It is an important probe to study the in-medium dynamics as it is predicted to be sensitive to the equation of state (EoS) of the produced medium. Minimum in the slope of directed flow ($dv_1/dy$) as a function of collision energy has been proposed as a signature of the first-order phase transition between hadronic matter and Quark-Gluon Plasma (QGP). Triangular flow $(v_3)$ typically arises from the initial state fluctuations and is expected to be uncorrelated with the reaction plane. However, recent measurements at lower collision energies (higher baryon chemical potential ($\mu_{B}$)) of $\sqrt{s_{NN}}$ = 2.4 and 3 GeV, show a correlation between $v_3$ and the first-order event plane angle ($\Psi_{1}$).\
In this presentation, we will report the measurements of $v_1\{\Psi_1\}$ and $v_3\{\Psi_1\}$ for $\pi$, K, $p$, net-kaon, net-proton, $d$, $t$, and ${}^{3}He$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 3.2, 3.5, 3.9, and 4.5 GeV taken in fixed-target mode from the second phase of the beam energy scan (BES-II) program at RHIC-STAR. We will show the dependencies of $v_1\{\Psi_1\}$ and $v_3\{\Psi_1\}$ on rapidity, $p_T$, centrality, and collision energy, and subsequently, discuss their physics implications. The experimental measurements will be compared with the results from the JAM model to understand the the transport properties of the medium at low collision energies.Speaker: SHARANG RAV SHARMA (IISER Tirupati) -
9:44 AM
Electromagnetic field fluctuation and its correlation with the participant plane in Au + Au and isobaric collisions at $\sqrt{s_{NN}}=200$ GeV 7m
Intense transient electric (${\bf E}$) and magnetic (${\bf B}$) fields are produced in the high energy heavy-ion collisions. The electromagnetic fields produced in such high-energy heavy-ion collisions are proposed to give rise to a multitude of exciting phenomenon including the Chiral Magnetic Effect. We use a Monte Carlo (MC) Glauber model to calculate the electric and magnetic fields, more specifically their scalar product $\bf{E}\cdot\bf{B}$, as a function of space-time on an event-by-event basis for the Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV for different centrality classes. We also calculate the same for the isobars Ruthenium and Zirconium at $\sqrt{s_{NN}}=200$ GeV. In the QED sector $\bf{E}\cdot\bf{B}$ acts as a source of Chiral Separation Effect, Chiral Magnetic Wave, etc., which are associated phenomena to the Chiral Magnetic Effect. We also study the relationships between the
electromagnetic symmetry plane angle defined by $\bf{E}\cdot\bf{B}$ ($\psi_{E.B}$) and the participant plane angle $\psi_{P}$ defined from the participating nucleons for the second-fifth order harmonics.Speaker: SK NOOR ALAM (ALIGARH MUSLIM UNIVERSITY) -
9:51 AM
Extracting baryon initial condition and diffusion - a Bayesian approach 7m
Bayesian analysis is employed to extract significant parameters related to the baryon initial condition and dissipation in the hot and dense strongly interacting matter produced in relativistic heavy ion collisions eventually leading towards significant understanding of the properties of the baryon rich QCD matter.
Speaker: Dr. Nachiketa Sarkar (iiser berhampur) -
9:58 AM
On Transportation of Baryon Number in pp Collision at √s = 0.9 and 7 TeV 13m
The estimation of the anti-baryon to baryon ratio is considered to be a useful tool for studying baryon number transport in pp, pA and AA collisions. For this study, the PYTHIA8.3 event generator with various tunes is used to measure the $\bar{\Lambda}$/Λ ratio as a function of rapidity (y), transverse momentum (pT), and multiplicity within both ALICE and LHCb acceptances. The results obtained using various MC data for pp collisions at √s = 0.9 and 7 TeV are compared with the experimentally measured values of ratio of $\bar{\Lambda}$/Λ of ALICE and LHCb experiments. Out of the various studied tunes of PYTHIA 8.3, the String Junction model is found to be the most successful one in describing the experimentally observed results. Evidence of considerable baryon number transportation from the beam fragmentation to the ALICE and LHCb acceptances could be recognized. The widths of the rapidity distribution of produced particles with the studied PYTHIA8.3 Monash and String Junction generated data are found to follow similar separate mass scaling for mesons and baryons as observed in AA collision at SIS, AGS to RHIC and SPS to LHC energies.
Speaker: Prof. Buddhadeb Bhattacharjee (Gauhati University (IN)) -
10:11 AM
Multiparticle Cumulants to Constrain the Initial State in Xe-Xe and Pb-Pb Collisions in the CMS Experiment 13m
Xenon (Xe) nuclei are deformed and have a non-zero quadrupole moment, whereas lead (Pb) nuclei are considered spherical in shape. The study of Xe-Xe collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{_{\mathrm{NN}}}} = 5.44$ TeV opens up a window to study nuclear deformation at LHC. When compared to Pb-Pb collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.36$ TeV, one can explore the dependence of the Fourier flow harmonics ($v_{n}$) on the size and initial-state geometry of the colliding systems. For the first time, correlations between higher-order moments ($\langle v_{n}^{k}v_{m}^{l}\rangle$, where $n,m = 2,3,4$ and $k,l = 2,4,6$) between two ($v_{2}$ and $v_{3}$ or $v_{2}$ and $v_{4}$) or even three flow harmonics ($v_{2}$, $v_{3}$ and $v_{4}$) are measured and compared between Xe-Xe and Pb-Pb collisions as a function of collision centrality. These new measurements have been calculated with multiparticle mixed harmonic cumulants (upto 8th order) using charged particles in the wide pseudorapidity region of the CMS detector ($|\mathrm{\eta}| < 2.4$) and in the transverse momentum range of $0.5 < p_\mathrm{T} < 3.0$ GeV/c. The results have also been compared to several theoretical model predictions. The observables measured in this analysis have been used to closely probe the non-linearities between $v_{2}$, $v_{3}$ and $v_{4}$ and their corresponding eccentricities $\epsilon_{2}$, $\epsilon_{3}$ and $\epsilon_{4}$. This not only helps us to constrain the deformation parameters of Xe nuclei, but can also significantly constrain initial-state model parameters and give us a better understanding of the evolution of the quark-gluon plasma created in heavy-ion collisions at LHC.
Speaker: Aryaa Dattamunsi (Indian Institute of Technology Madras (IN))
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9:00 AM
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9:00 AM
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10:40 AM
Parallel B: Collectivity Chair: Dong Jo Kim
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9:00 AM
Spin alignment of vector mesons in heavy-ion collisions 18m
The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). It provides a unique opportunity to probe the correlation between the polarized quark and antiquark in the strongly coupled quark-gluon plasma (sQGP) produced in relativistic heavy ion collisions, opening a new window to explore the properties of sQGP. In this talk, I will present a brief overview on theoretical and experimental advances in the study of vector meson's spin alignments in heavy-ion collisions.
Speaker: Prof. Qun Wang (University of Science and Technology of China) -
9:18 AM
Kubo formula for a dissipative spin hydrodynamic framework with spin chemical potential as the leading order term in the hydrodynamic gradient expansion 7m
We present a first-order dissipative spin hydrodynamic framework, where the spin chemical potential $\omega^{\mu\nu}$ is treated as the leading term in the hydrodynamic gradient expansion, i.e., $\omega^{\mu\nu}\sim \mathcal{O}(1)$. We argue that for the consistency of the theoretical framework, the energy-momentum tensor needs to be symmetric at least up to order $\mathcal{O}(\partial)$. We consider the phenomenological form of the spin tensor, where it is anti-symmetric in the last two indices only. A comprehensive analysis of spin hydrodynamics is conducted using both macroscopic entropy current analysis and microscopic Kubo formalism, establishing consistency between the two approaches. A key finding is the entropy production resulting from spin-orbit coupling, which alters the traditional equivalence between the Landau and Eckart fluid frames. Additionally, we identify cross-diffusion effects, where vector dissipative currents are influenced by gradients of both spin chemical potential and chemical potential corresponding to the conserved charge through off-diagonal transport coefficients. Two distinct methods for decomposing the spin tensor are proposed, and their equivalence is demonstrated through Kubo relations.
Speaker: Prof. Arpan Das (Birla Institute of Technology and Science Pilani, Pilani Campus) -
9:25 AM
Thermal diffusion properties of a rotating QGP medium 7m
This work involves the study of the effects of rotation on the thermal diffusion properties of the QGP medium. The noncentral heavy ion collisions could possess finite angular momentum with a finite range of angular velocity, so, rotation gets induced in the produced medium. Like other extreme conditions, the rapid rotation can conspicuously alter various properties of the QGP medium including its thermal diffusion properties. The thermal diffusion is associated with the rate of heat transfer in the medium. This is characterized by both the thermal conductivity and the specific heat at constant pressure. In determining the thermal conductivity, we have used the novel relaxation time approximation for the collision integral in the relativistic Boltzmann transport equation within the kinetic theory framework in conjunction with the finite angular velocity. It is observed that the onset of rotation enhances the thermal conductivity of the medium. Additionally, the specific heat at constant pressure gets increased due to the emergence of rotation, leading to larger changes in enthalpy and energy density with temperature as compared to the nonrotating case. However, with increasing angular velocity, the growth in the specific heat at constant pressure surpasses the rise in the thermal conductivity, resulting in a decrease in the thermal diffusion constant at finite angular velocity. Smaller value of the thermal diffusion constant indicates slower heat transfer in a rotating medium as compared to that in a nonrotating medium.
Speaker: Shubhalaxmi Rath (Universidad de Tarapacá) -
9:32 AM
Shear evolution in non-resistive magnetohydrodynamics with momentum dependent relaxation time 7m
Strong magnetic fields are expected to exist in the early stages of heavy ion
collisions and there is also an increasing evidence that the energy dependence of the
cross-sections can strongly affect the dynamics of a system even at a qualitative level.
This led us to the current study where we developed second-order non-resistive
relativistic viscous magnetohydrodynamics (MHD) derived from kinetic theory using an
extended relaxation time approximation (ERTA), where the relaxation time of the usual
relaxation time approximation (RTA) is modified to depend on the momentum of the
colliding particles. A Chapman-Enskog-like gradient expansion of the Boltzmann
equation is employed for a charge-conserved, conformal system, incorporating a
momentum-dependent relaxation time. The resulting evolution equation for the shear
stress tensor highlights significant modifications in the coupling with the dissipative
charge current and magnetic field. The results were compared with the recently
published exact analytical solutions for the scalar theory where the relaxation time
is directly proportional to momentum. Our approximated results show a very close
agreement with the exact results. This can lead us to transport coefficient calculations
for various theories for which exact results are not yet known.Speaker: Sunny Singh (IIT Gandhinagar) -
9:39 AM
Anisotropic Electrical Conductivity in Rotating Hadron Gas 7m
In non-central heavy-ion collisions, substantial orbital angular momentum (OAM) is produced and transferred to the QGP and hadronic matter, leading to effects like spin polarization and the chiral vortical effect. Previous studies have explored the impact of OAM on electrical conductivity under a non-relativistic, globally rotating QGP. In this work, we have developed a relativistic framework, relaxing earlier assumptions, to study the electrical conductivity of rotating hadronic matter. We have used the Boltzmann transport equation, integrating the Coriolis force that arises due to rotation in the hadron resonance gas (HRG) model. We have observed that similar to the Lorentz force, the Coriolis force induces anisotropy in the medium, which can be classified into three components: Hall ($\sigma^{\times}$), perpendicular ($\sigma^{\perp}$), and parallel ($\sigma^{||}$). In a rapidly rotating HRG, the Hall component (σ×) becomes dominant up to T ≈ 0.20 GeV, reflecting significant anisotropy in the medium.
References:
1. Effect of Coriolis Force on Electrical Conductivity Tensor for Rotating Hadron Resonance Gas, Nandita Padhan, Ashutosh Dwibedi, Arghya Chatterjee, and Sabyasachi Ghosh, Phys. Rev. C 110 (2024) 2, 024904
2. Effect of the Coriolis force on the electrical conductivity of quark matter: A nonrelativistic description, Ashutosh Dwibedi, Cho Win Aung, Jayanta Dey, and Sabyasachi Ghosh, Phys. Rev. C 109 (2023), 034914Speaker: Ms Nandita Padhan (National Institute of Technology Durgapur) -
9:46 AM
Elucidating QGP at finite baryon density with (3+1)D Bayesian analysis at the RHIC Beam Energy Scan program 13m
We present a systematic Bayesian analysis of Quark-Gluon Plasma (QGP) properties at finite baryon density using measurements of Au+Au collisions at the RHIC Beam Energy Scan program. The theoretical model simulates event-by-event (3+1)D dynamics of relativistic heavy-ion collisions with the state-of-the-art hybrid hydrodynamics and hadronic transport theory. We analyze the model’s 20-dimensional posterior distributions obtained using three Gaussian Process emulators with different accuracy and demonstrate the essential role of training an accurate model emulator in the Bayesian analysis [1]. Our analysis provides robust constraints on the Quark-Gluon Plasma’s transport properties and various aspects of (3+1)D relativistic nuclear dynamics using heavy-ion measurements from 7.7 to 200 GeV [2]. By running full model simulations with a few parameter sets sampled from the posterior distribution, we make timely predictions for pT differential observables, anisotropic flow rapidity decorrelation, and flow observables in O+O collisions with systematic theory uncertainties, which can be compared with the upcoming measurements from the STAR Collaboration. Finally, we highlight a detailed experimental design analysis to elucidate how individual experimental observables constrain different model parameters, providing valuable physics insights into the phenomenological model for heavy-ion collisions.
[1] H. Roch, S. A. Jahan and C. Shen, “Model emulation and closure tests for (3+1)D relativistic heavy-ion collisions,” Phys. Rev. C 110, no.4, 044904 (2024)
[2] S. A. Jahan, H. Roch and C. Shen, “Bayesian analysis of (3+1)D relativistic nuclear dynamics with the RHIC beam energy scan data,” arXiv:2408.00537 [nucl-th]Speaker: Ms Syed Jahan (Wayne State University) -
9:59 AM
Causal third-order viscous hydrodynamics from kinetic theory 7m
We derive a linearly stable and causal theory of relativistic third-order viscous hydrodynamics from the Boltzmann equation using the relaxation-time approximation. We employ a Chapman-Enskog-like iterative solution to the Boltzmann equation to obtain the viscous correction to the distribution function. Our derivation emphasizes the necessity of incorporating a new dynamical degree of freedom: specifically, an irreducible tensor of rank three. This approach differs from the recent formulation of causal third-order theory derived from the method of moments, which requires two dynamical degrees of freedom: an irreducible third-rank tensor and a fourth-rank tensor. We verify the linear stability and causality of the proposed formulation by examining perturbations around a global equilibrium state.
Speaker: Ms Pushpa Panday -
10:06 AM
Viscous effects of a hot QGP medium in time dependent magnetic field and their phenomenological significance 7m
Momentum transport in a medium is characterized quantitatively by its shear and bulk viscosities. The shear viscous coefficient ($\eta$) governs the momentum transport transverse to the hydrodynamic flow while its bulk counterpart ($\zeta$) does the same along the flow. In the context of quark gluon plasma (QGP), both $\eta$ and $\zeta$ are very important transport coefficients, controlling phenomenologically important quantities such as the QGP thermalization time, sound attenuation length, elliptic flow, etc.
It is now well known that large initial magnetic fields (which subsequently decay) are produced in the heavy-ion collisions at RHIC and LHC, which have been shown to influence the evolution of the QGP medium. However, most studies in the literature are made with the assumption of a constant magnetic field.
In this work, we have studied, for the first time, the impact of a realistic picture of a time dependent electric and magnetic field on the shear and bulk viscosities of the medium. Both the electric and magnetic fields are considered to be exponentially decaying with time, and the study is valid in the regime where the magnetic field strength is weak ($eB\ll T^2$). The evaluation has been done in the kinetic theory framework wherein we have solved the relativistic Boltzmann equation within the relaxation time approximation type collision kernel. We have shown that the constant weak field results as well as the $B=0$ results in the literature can be obtained as special cases of our general results. We have observed that the shear and bulk viscosities increase with time and conversely decrease with the strength of the magnetic field. To connect these observations with the experiment we have obtained the thermalization time, the sound attenuation length and other various phenomenologically significant quantities, using our results of $\eta$ and $\zeta$.
Speaker: Gowthama K K (Indian Institute of Technology Bombay) -
10:13 AM
Rapidity scan with DCCI at LHC energy 13m
In recent years, analyses using RHIC-BES data have been actively conducted to explore the high baryon number density region in the QCD phase diagram. Meanwhile, even in high-energy collisions, such as RHIC and LHC energies, the presence of high baryon number density matter in the forward rapidity region has been suggested [1]. This implies that, in addition to the analysis of BES data, a rapidity scan—analyzing data along the collision axis in such high-energy collisions—could serve as complementary ways to explore the high baryon number density region in the phase diagram. However, a model that provides a comprehensive description of the collision, from low $p_{T}$ to high $p_{T}$ and from midrapidity to forward rapidity, is essential for precise studies of the rapidity scan. Furthermore, since it is not at all trivial whether the produced matter has reached equilibrium in the forward rapidity region, a model capable of describing the dynamical evolution of both equilibrium and non-equilibrium components is required.
The state-of-the-art dynamical core-corona initialization (DCCI) model [2] is a novel framework that dynamically describes the space-time evolution of both equilibrium and non-equilibrium components including their interactions. Consequently, it has a great success in comprehensively describing experimental data of high-energy collisions from low $p_{T}$ to high $p_{T}$ at midrapidity. Thus, the DCCI model would be a strong candidate for rapidity scan studies. In this study, we extended the DCCI model by including baryon number current within the ideal hydrodynamics and modeled the dynamical deposition of baryon number into the fluid, enabling us to describe a gradual thermalization process of baryon number alongside the fluid formation through the dynamical initialization. Using this model, we aimed to clarify the baryon number distribution of each core (equilibrium) and corona (non-equilibrium) component across the entire system at the LHC energy. Specifically, we determined which regions of the QCD phase diagram are accessible with the rapidity scan at the LHC energy and showed which rapidity regions of high-energy collisions are comparable to the baryon number densities achieved in low-energy collisions. This study strongly supports the existence of high baryon number density as equilibrated matter in the forward rapidity region at the LHC energy.
[1] M. Li and J. I. Kapusta, Phys. Rev. C 99, 014906 (2019).
[2] Y. Kanakubo et al., Phys. Rev. C 105, 024905 (2022).Speaker: Shin-ei Fujii (Sophia Univ.) -
10:26 AM
Double-slit experiment at the femtometer scale with ALICE 13m
Double-slit experiment at the femtometer scale with ALICE
Speaker: Dr Arvind Khuntia (INFN Bologna)
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9:00 AM
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9:00 AM
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10:40 AM
Parallel C: High Baryon Density. Chair: Sayantan Sharma
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9:00 AM
Neutron star physics in the multi-messenger era 18m
Neutron star physics in the multi-messenger era
Speaker: Dr Ritam Mallick (INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH BHOPAL) -
9:18 AM
Impact of Dissipation on the Dynamics of Neutron Star Mergers 18m
Impact of Dissipation on the Dynamics of Neutron Star Mergers
Speaker: sreemoyee sarkar (MPSTME, NMIMS University) -
9:36 AM
Implications of Gravitational Waves Data on Dark Matter Admixed Neutron Stars 13m
A decade of Gravitational Wave observations by LIGO-Virgo collaborations has opened a new window to the Universe peeking into the exotic lives of stellar black holes and compact stars. With the observation of GW170817, the first GW observation from coalescence of binary neutron stars along with the associated multi-wavelength spectral observation such as $\gamma$-rays, X-rays, UV, IR and Radio, leading to plethora of information about such systems initiated what is fondly called as the multi-messenger era in Astronomy \& Astrophysics and cosmology. This particular observation provided vital inputs to constrain the theoretical aspects of the underlying equation of state (EoS) and therefore on the global properties of neutron stars as well, be it mass (2.73 - 3.29) $M_{\odot}$ or inferred radius of the canonical 1.4 $M_{\odot}$ object which turns out to be $\approx$ 14 km. In the present scenario, many such observations are expected to happen which may sprung surprises in the very domain of observational Astrophysics and therefore to the underlying theories as well.
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Theories, being the only way to understand the composition of neutron stars/ pulsars need to compliment the observations of their properties and signatures from various dynamical aspects of these compact systems. Within the mean field framework, we would present some of these results where the neutron star will be composed of various baryonic resonances as well as exotic particles such as dark matter. Finally the results will be tested to the compatibility of the GW data available.Speaker: Dr Tuhin Malik (CFisUC, Department of Physics, University of Coimbra, Portugal) -
9:49 AM
Axion effects on the nonradial oscillations of neutron stars 13m
We investigate the effects of including strong charge parity violating effects through axion field on the structure and the oscillation modes of the neutron stars with the possibility of a quark matter core. The effects of axions in quark matter is described through a t Hooft determinant interaction in the flavor space within the ambit of a three flavor Nambu--Jona-Lasinio model. The presence of axions seem softens the equation of state with having a larger core of quark matter compared to the case when their absence. This leads an enhancement of the f mode oscillation frequencies in hybrid stars.
Speaker: Dr Deepak Kumar (Indian Institute of Science Education and Research Bhopal, Madhya Pradesh, 462066, India) -
10:02 AM
Deciphering accretion-driven starquakes in recycled millisecond pulsars using gravitational waves 13m
Recycled millisecond pulsars are susceptible to starquakes as they are continuously accreting matter from their binary companion. A starquake happens when the rotational frequency of the star crosses its breaking frequency. In this study, we perform a model analysis of an accreting neutron star suffering a starquake. We analyse two models: a spherical star with accreting mountains and a deformed star with accreting mountains. We find that as the star crosses the breaking frequency and suffers a starquake, there is a sudden change in the continuous gravitational wave signal arriving from it. The amplitude of the gravitational wave signal increases suddenly both for the spherical and deformed star. For the spherical star, the accreting matter entirely dictates the amplitude of the gravitational wave. For the deformed star, both the accreting matter and the deformation from spherical symmetry play a significant role in determining the amplitude of the gravitational wave signal. This sudden change in the continuous gravitational wave signal in recycled millisecond pulsars can be a unique signature for such pulsars undergoing a starquake.
Speaker: Kamal Krishna Nath (National Institute of Science Education and Research) -
10:15 AM
SYMMETRIC AND ASYMMETRIC PROPERTIES OF NEUTRON STAR 13m
Our approach offers a phenomenological model for investigating nuclear matter by employing the modified relativistic Dirac formalism coupled with the σ–ω and ρ mesons in the quark-meson coupling model. By considering scalar and vector linear potential for quark confinement and accounting with quantum corrections such as the centre-of-mass motion, gluonic, and pionic corrections, we establish a foundation to calculate fundamental properties of nucleons and calculate nucleon mass in a vacuum as well as in medium. Our methodology then allows for a thorough exploration of nuclear matter properties, extending into nuclear EOS, binding energy, symmetry energy, and thermodynamic instability, which are important for understanding nuclear interactions and matter under extreme conditions. The systematic exploration of the correlation between symmetry energy and its density slope provides valuable data that can help refine existing nuclear models and provide a deeper understanding of nuclear matter in beta equilibrium at finite densities. In addition, we examine the mass-radius variations of neutron stars.
Speaker: ANSUP KUMAR PANDA (Berhampur University) -
10:28 AM
Gravitational Wave Signatures of Spin-Polarized Dense Matter in Neutron Stars 7m
The presence of ultra-strong magnetic fields in magnetar induces significant spin polarization of baryons, profoundly affecting the equation of state (EoS) of dense nuclear matter. This study employs the CDM3Y interaction, a G-matrix-based M3Y interaction, within the Hartree-Fock framework to model spin-polarized nuclear matter in the presence of such extreme magnetic fields. By incorporating spin polarization into the EoS, we analyze its impact on the structure and deformability of neutron stars.
The study explores gravitational wave (GW) signals generated by time-varying quadrupole moments and it is proposed that spin polarized EoS, modifying the star's quadrupole moment can affect the amplitude and characteristics of the emitted GWs.
Future GW observations also will be able to offer unique opportunity to constrain the spin polarization of highly magnetized neutron stars, providing valuable insights into the spin-polarized physics of dense matter.Speaker: Biswarup Das (PhD. scholar)
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Parallel D: Small system. Chair: Buddhadeb Bhattacharya
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9:00 AM
Production of light-flavoured particles in ALICE RUN 3 data for pp collisions 13m
Multiplicity-dependent yield ratios of light-flavour particles, such as p and strange hadrons relative to $\pi$, provide key insights into hadron production mechanisms and strangeness enhancement across collision systems. Observable like (multi-)strange to non-strange ratios show a smooth transition from small to large systems, shedding light on collective behaviour and production dynamics. Leveraging the high-luminosity data from LHC Run 3 and the advanced O$^2$ (online-offline) framework, the ALICE experiment enables precise measurements of these phenomena in pp collisions at $\sqrt{s}=13.6$ TeV. This work presents the results on particle yield ratios as functions of charged-particle multiplicity ($\textrm{d}\it{N}_\textrm{ch}/\textrm{d}\eta$) are compared to state-of-the-art QCD-inspired models to understand further the microscopic origins of observed phenomena such as strangeness enhancement and collective behaviour in hadronic collisions.
Speaker: Banajit Barman -
9:13 AM
First measurement of high $p_\mathrm{T}$ azimuthal anisotropy using subevent cumulants in pPb collisions at CMS 7m
Measurements at the LHC have provided evidence for collective behavior in high-multiplicity proton-lead (pPb) collisions through multiparticle correlation techniques. Yet, no conclusive evidence of jet quenching, indicating the energy loss of high-$p_\mathrm{T}$ partons as they traverse the medium, has been detected in pPb. This raises the intriguing question: How can a medium described by hydrodynamics, and that significantly modifies the distribution of final-state hadrons, yet has no significant impact on the distribution of high-pT particles? To investigate this, a comprehensive study of differential Fourier coefficients ($v_{n}$) in particle transverse momentum ($p_\mathrm{T}$) and event multiplicity is presented in pPb collisions recorded by the CMS experiment at a nucleon-nucleon center-of-mass energy $\sqrt{s_{_{\mathrm{NN}}}} = 8.16$ TeV. In particular, new measurements of $p_\mathrm{T}$-differential multiparticle cumulants using the subevent method probes an extended phase space region up to a high particle $p_\mathrm{T}$. Additionally, we compare the results between pPb and PbPb collisions in the same multiplicity window. This comparison will help assess similarities and differences in the medium's interaction with high-$p_\mathrm{T}$ particles in these two collision types.
Speaker: Rohit Kumar Singh (Indian Institute of Technology Madras (IN)) -
9:20 AM
Understanding biases in experimental multiplicity estimations for pp collisions at the LHC 13m
Measurements from the LHC and RHIC of proton-proton (pp) and proton-lead (pPb) collisions have revealed that the onset of phenomena normally associated with heavy-ion collisions also appear in smaller collision systems, particularly in collisions that produce large particle densities. However, unlike their larger heavy-ion counterparts, multiplicity production in pp collisions is dominated by large, spatial fluctuations. The origin of these fluctuations is model-dependent, currently understood to be driven by large parton showers or collisions with several multiple-parton interactions.
Consequently, measurements of high multiplicity pp collisions will necessarily be biased toward different phenomenological processes, considering which phase-space the multiplicity estimate is performed.This is particularly the case for experiments at RHIC and the LHC, where various subdetectors have limited azimuthal and pseudorapidity coverage, complicating direct comparisons of multiplicity-differential studies between different experiments.
This contribution examines how the different experiments at RHIC and the LHC measure multiplicity production in pp collisions, and discusses whether it is feasible to directly compare different estimations of "high-multiplicity" events selected with nonidentical phase-space constraints. Model simulations from state-of-the-art Monte Carlo generators are presented to highlight that these effects arise not from detector geometries or inefficiencies, but rather from the phase-space selection itself in relationship to the underlying physics processes. Furthermore, several observables commonly utilized to estimate the size of the underlying event, such as transverse spherocity, transverse charged particle density, and flattenicity will be discussed in this context.
Speaker: Adrian Fereydon Nassirpour (Sejong University (KR)) -
9:33 AM
Exploring the effects of $\alpha$-clustered structure of $^{16}$O nuclei in anisotropic flow fluctuations in $^{16}$O-$^{16}$O collisions at the LHC within a CGC+Hydro framework 7m
Azimuthal anisotropy quantified as anisotropic flow coefficients are important observables that can provide key information about the collectivity of the system formed during heavy-ion collisions. The anisotropic flow coefficients are sensitive to both the geometrical configuration of the collision overlap region and the transport properties of the medium. Recently, hints of collectivity in small collision systems like pp and p-Pb have been reported, which are traditionally used for baseline measurements to study the quark-gluon plasma (QGP) signatures and cold nuclear matter effects in heavy-ion collisions. This makes O-O and p-O collisions interesting, as they bridge the multiplicity gap between pp, p-Pb, and Pb-Pb collisions and can provide pivotal information about the observed QGP signatures in small systems. In addition, $^{16}\rm{O}$ is a doubly magic nucleus and possesses $\alpha$-cluster nuclear configuration, where one can imagine four $\alpha$-particles arranging themselves at the corners of a randomly rotated regular tetrahedron.
In this contribution, we shall present the effect of the presence of the $\alpha$-cluster nuclear configuration of $^{16}\rm{O}$ on elliptic flow ($v_{2}$), triangular flow ($v_{3}$) and elliptic flow fluctuations in O-O collisions at $\sqrt{s_{\rm NN}}=7$ TeV using a hybrid CGC+hydro model based on IPGlasma+MUSIC+iSS+UrQMD framework. The results of $\alpha$-cluster nuclear configuration of $^{16}\rm{O}$ are also compared with the Woods-Saxon nuclear profile. The results show an enhanced value of $v_{2}$ and $v_{3}$ in the highest multiplicity regions for the $\alpha$-cluster case as compared to the Woods-Saxon profile. Further, a strong increase in the value of $v_{3}/v_{2}$ is observed when going from the top 10-20% to the top 0-10% multiplicity class for the case with $\alpha$-clusters. Additionally, we find that the elliptic flow fluctuations show opposite trends with a decrease in final state multiplicity for $\alpha$-cluster and Woods-Saxon nuclear density profiles. We conclude that the observables related to fluctuations are more sensitive and suited to study the effects of the $\alpha$-clustered geometry in O-O collisions.
Speakers: Mr Suraj Prasad (Indian Institute of Technology Indore (IN)), Raghunath Sahoo (Indian Institute of Technology Indore (IN)) -
9:40 AM
Exploring flow signals and jet modification in small systems at the LHC 13m
In ultrarelativistic collisions of nuclear matter, one of the emerging topics is the possible formation of quark-gluon plasma (QGP) droplets in small collision systems. Recent measurements with flow-like behavior imply collectivity in high-multiplicity pp collisions at the LHC. It is also crucial to look for evidence of possible jet-quenching effects in such systems. The results of jet quenching studies in pp collisions at $\sqrt{s} = 13$ TeV will be discussed. The di-hadron correlations are measured for various $p_{\rm T}$-intervals as a function of charged particle multiplicity. Since small collision systems are biased through non-flow effects such as jets, it is important to develop methods for unbiased flow measurements. The recent progress in non-flow subtraction used to measure flow in small collision systems will be discussed [1,2]. These studies offer the testing of the limit of multiplicity for flow signals in small systems. This method will also be applied in studying the charm flow and fragmentation in small systems by accounting for the sophisticated background subtraction involved in $D^0$ meson studies. Furthermore, these results will be compared to various model calculations such as PYTHIA8, PYTHIA String shoving, EPOS, AMPT, and JETSCAPE, wherever possible.
References:
1. Phys. Rev. C 108, 034909 (2023)
2. ALICE Collaboration, JHEP 03 (2024) 092Speaker: Neelkamal Mallick (University of Jyväskylä) -
9:53 AM
Study of identified particle production in high multiplicity pp collisions at $\sqrt{s} = $13 TeV with ALICE at the LHC 13m
In proton-proton and proton-lead collisions at the LHC, signatures like those observed in lead-lead collisions arise as the multiplicity of charged particles produced in the collision increases. In AA collisions, these features are attributed to the formation of a deconfined state of matter formed by quarks and gluons, known as the Quark–Gluon Plasma (QGP). Most notably, these include a mass-dependent hardening of the transverse momentum distributions (explained as an effect of the radial flow) and an enhancement of strange hadrons (understood as a release from canonical suppression).
The origin of these phenomena in small collision systems has yet to be understood, warranting new measurements that bridge the gap between small and large collision systems. This contribution presents the measurements of $\pi^{\pm}$ $\text{K}^{\pm}$ and p($\bar{\text{p}}$) obtained in high-multiplicity triggered events with the ALICE detector at the LHC.
This new set of results allows us to probe the light-flavour particle-production mechanisms at unprecedented charged-particle multiplicities of about five times the one obtained on average in pp collisions, filling the gap between pp and larger systems. The results are compared as a function of the charged-particle multiplicity to measurements in pp, pA, and AA collisions. The particle-production mechanisms affecting dynamics and hadrochemistry are tested by measuring the average transverse momentum and integrated particle yields. The results are compared to predictions from the state-of-the-art Monte Carlo models such as Pythia and EPOS.Speaker: Navneet Kumar (Panjab University (IN)) -
10:06 AM
Multiplicity and rapidity dependent study of (multi)-strange hadrons in small collision system using the STAR detector 13m
Strangeness enhancement has long been considered as a signature of the quark-gluon plasma formation in heavy-ion collisions. Strangeness enhancement has also been observed in small systems at the LHC, but the underlying physics is not yet fully understood. This motivates studies of strange hadron production in small systems at RHIC, where the energy density of the created system is expected to be smaller than that at the LHC and therefore a hot and deconfined medium is less likely to be created. Results on the multiplicity dependence of strange hadron production in small systems can be compared to peripheral heavy-ion collisions, and help to understanding the role of event multiplicity in strange hadron production. Study of rapidity asymmetry ($\rm Y_{Asym}$) of the strange hadron production and nuclear modification factors ($ \rm R_{dAu}$) in $d$+Au collisions can also give insight on cold nuclear matter effects.
We present measurements of (multi)-strange hadrons ($K_S^0$, $\Lambda$, $\Xi$ and $\Omega$) in $d$+Au collisions at $\sqrt{\rm s_{\rm NN}}$ = 200 GeV, collected by STAR in 2016. We investigate the multiplicity dependence of (multi)-strange hadron transverse momentum ($p_{\rm{T}}$) spectra, $p_{\rm{T}}$-integrated rapidity density distributions (dN/dy), average transverse momentum ($\langle p_{\rm{T}} \rangle$), and yield ratios to pions. $ \rm R_{dAu}$ and $\rm Y_{Asym}$ for these particles are presented. The implications of these measurements on the possible formation of a hot and deconfined medium and the origin of strangeness enhancement in small systems are discussed.
Speaker: Ishu Aggarwal -
10:19 AM
Understanding medium anisotropy in p–O and p–C collisions at the LHC with exotic $\alpha$-clustered nuclear density profiles 7m
One of the major motivations for the planned p--O and O--O collisions at the LHC is to explore the possibilities of small system collectivity. Such transverse collective expansion results in the appearance of long-range azimuthal correlation and is quantified via the coefficients, $v_{\rm n}$, of Fourier expansion of the azimuthal momentum distribution of the final-state particles. These flow coefficients serve as the medium response to the initial spatial anisotropy and are sensitive to the density profile of the colliding nuclei. Light nuclei such as $^{12}\rm C$ and $^{16}\rm O$ are theorized to possess extra stability due to the presence of an $\alpha$-clustered arrangement of its nucleons. In this context, studies on ultra-relativistic p--A collisions involving $^{12}\rm C$ or $^{16}\rm O$ nuclei can serve a dual purpose: exploring small system collectivity along with investigating the effects of a clustered nuclear geometry on the medium anisotropy. With this motivation, for the first time, we study p--O and p--C collisions at $\sqrt{s_{\rm NN}}$ = 9.9 TeV through a multi phase transport model (AMPT) simulations. We attempt to explore how an initial $\alpha$-clustered nuclear structure of $^{16}\rm O$ and $^{12}\rm C$ influences the production yield, initial eccentricities and flow coefficients in the final state, in comparison to an unclustered density profile, Sum-Of-Gaussians (SOG). The flow coefficients are estimated via a two-particle Q-cumulant method.
The results show that $\langle\epsilon_{2}\rangle$ varies with centrality in a unique manner for $\alpha$-clustered p--O and p--C collisions, similar to O--O collisions. However, the centrality dependence of $\langle\epsilon_{2}\rangle$ and $\langle\epsilon_{3}\rangle$ is not effectively carried forward to the final state $v_{2}$ and $v_{3}$, owing to lesser participants. We also see that the dependence of $v_{2}$ on centrality is much less in comparison to $v_{3}$, which is reflected in the $v_{3}$/$v_{2}$, $v_{2}$/$\langle\epsilon_{2}\rangle$ and $v_{3}$/$\langle\epsilon_{3}\rangle$ ratios studied in our work. We notice that the $\alpha$-clustered case shows almost a flatter trend of $v_{3}$ with centrality than the corresponding collisions with a SOG profile, possibly indicating the discretized internal structure of an $\alpha$-clustered nucleus. Thus, by probing the effects of the nuclear structure employing ultra-relativistic collisions, this work serves as a transport-model-based prediction for the upcoming p--O collisions in the LHC Run$~$3.
Speaker: Aswathy Menon K R (Indian Institute of Technology Indore (IN)) -
10:26 AM
Spherocity-Dependent Study of Relative Transverse Multiplicity Activity Event Classifier in the Underlying Event 7m
This study investigates the intricate relationship between transverse spherocity ($S_{0}$) and the relative transverse multiplicity activity event classifier ($R_{T}$) in proton-proton collisions at the Large Hadron Collider (LHC) with a center-of-mass energy of 13 TeV. Through a detailed analysis across different spherocity regions, we examine various observables to understand underlying event dynamics in high-energy particle collisions. We have used the PYTHIA 8 Monte-Carlo (MC) with a different implementation of color reconnection and rope hadronization models to demonstrate the proton-proton collision data at $\sqrt s$ = 13 TeV. The sensitivity to the multi-partonic interaction is studied using a new differential approach to understand the underlying event and jetty-like domain. Furthermore, the baryon-to-meson production ratio and the average transverse momentum ($p_{T}$) are evaluated across $R_{T}$ for selected spherocity classes, revealing significant dependencies on the event topology. These measurements offer insight into the complex nature of strange particle production and underlying event structure in high-energy collisions, with implications in quantum chromodynamics (QCD) studies. Experimental confirmation of these results is feasible using ALICE Run 3 data which will provide more insight
into the soft physics in the transverse region which is useful to understand the small system dynamics.Speaker: Anuraag Rathore (Tata Institute of Fundamental Research (IN))
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Coffee / Tea Break
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12:40 PM
Parallel A: Future experiments, Detectors. Chair: Prabhakar Palni
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11:00 AM
Status overview of Korean group activities for MTD Endcap Timing Layer development 18m
During the High-Luminosity phase of the LHC (HL-LHC), the CMS experiment will be upgraded with a new MIP Timing Detector (MTD), which will provide precise time measurements for charged particles up to a pseudorapidity of |eta| = 3. This precise timing capability will help address the complex pile-up environment anticipated at HL-LHC, thereby extending the experiment's sensitivity to new physics. The forward region of the MTD, known as the Endcap Timing Layer (ETL), will cover a pseudorapidity range of 1.6 < |eta| < 3 and will be equipped with Low-Gain Avalanche Diodes (LGADs) paired with the Endcap Timing Read Out Chip (ETROC). This talk will present an overview of the activity of the Korean MTD group.
Speaker: Dong Ho Moon (Chonnam National University (KR)) -
11:18 AM
Physics overview of CBM detector at FAIR 18m
Physics overview of CBM detector at FAIR
Speaker: Supriya Das (Bose Institute (IN)) -
11:36 AM
Performance study of Gas Electron Multiplier chamber for future heavy ion experiment 13m
Gas Electron Multiplier (GEM) is a cutting edge Micro Pattern Gaseous detector (MPGD) technology suitable as tracking device in high rate Heavy-Ion (HI) experiments for their high rate handling capability and good spatial resolution. The performance studies including the detector efficiency, gain, energy resolution and also the long-term stability study under high radiation are the most important aspects need to be investigated before using the detector in any experiments. In this work all of the above mentioned aspects are investigated for a single mask triple GEM chamber prototype operated with premixed Ar/CO$_2$ gas mixtures using a 5.9 keV $^{55}Fe$ X-ray source. The gain and energy resolution are corrected for the variation of ambient temperature/pressure ratio (T/p). The effect of the variation of bias current on the performance of the detector is also studied. The details of the experimental setup, methodology, and results will be discussed.
Speaker: SUBIR MANDAL (Bose Institute) -
11:49 AM
Development of an ALPIDE telescope and its test results at PF-AR in KEK 13m
The ALICE collaboration at the LHC is preparing for the Inner Tracking System 3 (ITS3) upgrade during the Long Shutdown 3 period. A chip test setup, namely, a telescope, consisting of 6 ALPIDE chips aligned along the beam path, enables us to reconstruct beam particle tracks and investigate a DUT (Device Under Test) chip placed between the chip layers. The Korean ALICE TeleScope, named KATS, was developed following the CERN version. The Korean ALICE experiment group (KoALICE) successfully conducted a test operation of KATS with a bent ALPIDE as a DUT using an electron beam at PF-AR, KEK. This talk will introduce the KATS and its performance with the test results.
Speaker: Kyungrim Woo (Pusan National University (KR)) -
12:02 PM
Development of Ultra-Thin LGADs with Enhanced Timing Capabilities and Radiation Hardness for Future Collider Applications 13m
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage[margin=1in]{geometry}\begin{document}
\title{Development of Ultra-Thin LGADs with Enhanced Timing Capabilities and Radiation Hardness for Future Collider Applications}
\author{Jaideep Kalani$^{1}$, Saptarshi Datta$^{2}$, Ganesh J. Tambave$^{2}$, Prabhakar Palni$^{1}$\
\small $^{1}$Indian Institute of Technology Mandi, Mandi - 175005, INDIA\
\small $^{2}$National Institute of Science Education and Research, Odisha - 752050, INDIA}
\date{}
\maketitle\begin{abstract}
This study investigates Low Gain Avalanche Detectors (LGADs) for future particle collider experiments, aiming to improve timing resolution ($<$ 20 ps) under very high-radiation environments. Using the WeightField2 simulation program, we optimized an n-in-p type LGAD design, focusing on ultra-thin sensors ($\sim$$<$ 50 $\mu$m) with p-doped Silicon bulk. Our results show that a 20 $\mu$m thick sensor achieves optimal performance. \sloppy Simulations were performed under High Luminosity LHC conditions (temperature $ \approx -15 $ $^{\circ}$C, luminosity $ \approx 7 \times 10^{34} \, \text{cm}^{-2} \, \text{s}^{-1}$), taking into account radiation damage, gain quenching, and lattice defects. Further studies were extended to Silicon Carbide (SiC) bulk material due to its superior properties, such as a wide band-gap and high atomic displacement energy, which provide strong resistance to irradiation. Its high electron saturation drift velocity and thermal conductivity make it a fast-responding detector with lower thermal sensitivity. After irradiation, the study investigates fast charge collection, breakdown voltage, leakage current, and radiation tolerance, comparing these with conventional Silicon-based LGADs. For instance, SiC-based LGADs demonstrated lower leakage current and enhanced radiation tolerance. Additionally, simulations were conducted using laser with wavelength falling in near-infrared region, to observe charge collection across the detector strip, identifying the optimal zone for MIP hitting. These findings underline the potential of optimized LGADs in maintaining performance under high radiation regime.\end{abstract}
\noindent \textbf{Keywords:} LGAD, timing resolution, radiation hardness, ultra-thin sensors, Silicon Carbide, WeightField2 simulation
\end{document}
Speaker: Mr Jaideep Kalani (Tata Institute of Fundamental Research (IN)) -
12:15 PM
Optimising Gas Electron Multiplier for improved detector performance using ANSYS and Garfield++ 7m
Micro-Pattern Gas Detectors (MPGDs) are a type of gaseous ioniza-
tion detector that use microelectronics. They are characterized by a very small gap between the anode and cathode electrodes, which are main-
tained at high voltage and are usually filled with gaseous medium. When
a high-energy particle interacts with the gas, it produces ions and electrons that are propelled in opposite directions by the electric field in the detector region. The electrons that are deflected can induce further ionization,resulting in more electron-ion pairs through an avalanche effect. These resulting particles can be detected with high precision at the readout stage.One specific kind of MPGD is the Gas Electron Multiplier (GEM), which
is made from a polyimide film sandwiched between two conductive layers
of copper under a high voltage difference. Tiny holes in the foil allow for electron avalanches to occur. However, the current design of the GEM
detector, used in various experiments is suboptimal for achieving maxi-
mum gain and performance. This study aims to achieve the best possible
configuration of GEM foil to get optimal electric field, higher gain and
lesser back-flow of ions without compromising the detector’s capability.
In this research, we have modified the geometry of the GEM detector to
improve gain, minimize ion back flow and enhance overall performance.
This geometry has been modeled in ANSYS and additional analyses have
been conducted using Garfield++.Speaker: poojan angiras
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Parallel B: Collectivity. Chair: Maya Shimomura
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11:00 AM
Global spin polarization of $\Lambda$ and $\overline{\Lambda}$ hyperons in Au+Au collisions at RHIC-STAR 13m
In non-central heavy-ion collisions, large angular momentum is generated, leading to significant vorticity and subsequent spin polarization of particles with finite spin. The global polarization of $\Lambda$ and $\overline{\Lambda}$ hyperons ($P_\Lambda$ and $P_{\overline{\Lambda}}$), measured along the direction of global angular momentum, serves as an effective probe of both vorticity and spin degrees of freedom. $P_\Lambda$ has been measured over a wide range of collision energies. The data from Beam Energy Scan II (BES-II) program at RHIC, including the collider and recent Fixed-Target (FXT), have provided a unique opportunity to study spin degrees of freedom in a wide region of baryon density. In this energy range, $P_\Lambda$ is observed to be sensitive to the equation of state of the nuclear medium.
In this talk, we will present measurements of global $\Lambda$ polarization in Au+Au collisions at $\sqrt{s_{NN}} = 3.0, 3.2, 3.5, 3.9, 4.5, 5.2$, and $6.2$ GeV, along with global $\Lambda$ and $\bar{\Lambda}$ polarization and their differences in Au+Au collisions at $\sqrt{s_{NN}} = 7.7, 9.2, 11.5, 14.6, 17.3$, and $19.6$ GeV from BES-II. The dependence of the measured global polarization on collision energy, centrality, rapidity, and transverse momentum will be discussed.
Speaker: Tan Lu (Institute of Modern Physics, Chinese Academy of Sciences) -
11:13 AM
Recent results on light nuclei and hypernuclei production at RHIC 18m
This is a mini-review talk.
Speaker: Chitrasen Jena (Department of Physics, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati 517507, Andhra Pradesh, India) -
11:31 AM
Probing the hottest droplet of fluid through correlations and fluctuations of collective observables 13m
The matter produced in an ultra-relativistic heavy-ion collision, dubbed as the QGP, posses a temperature $10^5$ times that of Sun's core and survives for a very short time ($10^{-22}$ s), producing thousands of particles which exhibit collective motion described by some global observables, e.g. charged particle multiplicity($N_{ch}$), mean transverse momentum per particle ($[p_T]$), harmonic flow ($V_n$) etc. Fluctuations and correlations between these observables contain crucial information of the QGP medium as well as of the nuclear properties. We study in hydrodynamic model Pearson correlation coefficient between $[p_T]$ and $v_n^2$, which serves as an excellent tool to map the correlations present in the initial state. We generalize such correlations to higher order in terms of the normalized symmetric cumulants which put additional useful constraints on the initial state models. To probe $p_T$-dependent event-by-event fluctuation of $V_n$, we study factorization breaking coefficient, which shows decorrelation at higher $p_T$-bins. We study these observables for different centralities and compare our model results with the experimental data. We further our study for the fluctuation of $[p_T]$ in ultra-central Pb+Pb collision and explain the sudden fall in the ATLAS data over a narrow range of multiplicity. We show in our model that this sharp fall is a consequence of the underlying thermalization assumption of the system. We also make further robust predictions for mean, skewness and kurtosis in the ultra-central domain. We also study recently introduced $v_0(p_T)$ which is similar to anisotropic flow in terms of its collective nature and, it correlates the spectra with the event-by-event mean transverse momentum per particle. Furthermore, we study multiplicity in ultra-central p+Pb collision as a function of pseudorapidity, and centrality defined from the energy deposited in a calorimeter, and show that fluctuations of the multiplicity and the centrality estimator are predominantly due to quantum fluctuations, with impact parameter fluctuations playing negligible role. We argue that by repeating the same analysis with a different centrality estimator, direct information can be obtained about the rapidity decorrelation in particle production. Through these above-mentioned studies, we present an overall picture how correlations and fluctuations of the collective observables can be used to study the dynamics and properties of the QGP medium. (arXiv: 2103.15338, 2109.07781, 2303.15323, 2405.14671, 2407.17313)
Speaker: Rupam Samanta (AGH University of Krakow, Poland) -
11:44 AM
Insights into Nuclear Modification Factors in O-O collisions at LHC energies with a transport model 7m
Extensive research at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) on Pb-Pb and Au-Au collisions have helped us develop and understand the properties of the quark-gluon plasma (QGP) in heavy-ion collisions. Recent investigation suggests that QGP-droplets may occur in small collision systems such as high-multiplicity pp collisions. O-O collisions are anticipated in the upcoming run at the LHC. This will provide an important and timely opportunity to investigate the effects seen in high-multiplicity pp and p-Pb collisions with a system having a similar number of participating nucleons and final-state multiplicity but with a larger geometrical transverse overlap, thereby enhancing jet-quenching effects, which depend on path length. In the current work, we have implemented both Woods-Saxon and an α-cluster tetrahedral structure in the oxygen nucleus using a multi-phase transport (AMPT) model. We report the nuclear modification factor (RAA) for all charged hadrons and identified particles for most central, mid-central, and peripheral collisions in the O-O collisions at $\sqrt{\rm{s_{NN}}}$ = 7 TeV in the case of both Woods-Saxon and α-clustered density profiles. Additionally, we study the rapidity dependence of RAA for all charged hadrons. We have also observed the behavior of RAA with the same multiplicity environment between O-O and Pb-Pb collisions. A study like this will assist us in understanding the implications of nuclear density profiles and provide a realistic baseline measurement to compare experimental results in the future.
Speaker: Debadatta Behera (Indian Institute of Technology Indore (IN)) -
11:51 AM
Diffusion coefficient matrix for multiple conserved charges: a Kubo approach 13m
The strongly interacting matter created in relativistic heavy-ion collisions possesses several conserved quantum numbers, such as baryon number, strangeness, and electric charge. The diffusion process of these charges can be characterized by a diffusion matrix that describes the mutual influence of the diffusion of various charges. We derive the Kubo relations for evaluating diffusion coefficients as elements of a diffusion matrix. We further demonstrate that in the weak coupling limit, the diffusion matrix elements obtained through Kubo relations reduce to those obtained from kinetic theory with an appropriate identification of the relaxation times. We illustrate this evaluation in a toy model of two interacting scalar fields with two conserved charges.
Speaker: Sourav Dey (National Institute of Science Education and Research(INDIA)) -
12:04 PM
Relativistic second-order spin hydrodynamics: A correlation function approach using Zubarev's non-equilibrium statistical operator 7m
Utilizing Zubarev's nonequilibrium statistical operator, we derive the second-order expression for the dissipative tensors in relativistic spin hydrodynamics, namely the rotational stress tensor ($\tau_{\mu\nu}$), boost heat vector ($q_\mu$), shear stress tensor ($\pi_{\mu\nu}$), and bulk viscous pressure ($\Pi$). The emergence of the first two terms, $\tau_{\mu\nu}$ and $q_\mu$, is attributed to the inclusion of the antisymmetric part in the energy-momentum tensor. In this work, we also treat the spin density ($S^{\mu \nu}$) as an independent thermodynamic variable alongside energy density and particle density, leading to an additional transport coefficient characterized by the correlation between $S^{\mu \nu}$ and $\tau_{\mu\nu}$. Finally, we derive the evolution equations for the aforementioned tensors—$\tau_{\mu\nu}$, $q_\mu$, $\pi_{\mu\nu}$, and $\Pi$.
Speaker: Mr Abhishek Tiwari (Indian Institute of Technology Roorkee) -
12:11 PM
Investigating the Chiral Magnetic Wave at RHIC-STAR 7m
In heavy-ion collisions, the Chiral Magnetic Wave (CMW) is theorized to produce an electric quadrupole moment, leading to differences in elliptic flow between positively and negatively charged particles. This CMW signal can be detected by examining the correlation between charge-dependent elliptic flow and event charge asymmetry. This study focuses on the difference in covariance of elliptic flow ($v_2$) and charge asymmetry $A_{\textup{ch}}$ for positively and negatively charged particles across various collision centralities.
To explore collision system dependence, we will analyze results from Au+Au collisions as well as isobar (Ru+Ru and Zr+Zr) collisions at a center-of-mass energy of $\sqrt{s_{\textup{NN}}}$ = 200 GeV. A comparison between the two isobar systems will be conducted to investigate any potential enhancement of the CMW signal in Ru+Ru collisions, which may be attributed to the stronger magnetic field generated by the additional four protons in Ru. Additionally, we will present correlations between triangular flow ($v_3$) and $A_{\textup{ch}}$ to assess background contributions.
Speaker: Ms Ankita Singh Nain (DAV College, Chandigarh) -
12:18 PM
Production of Light Nuclei in Heavy-Ion Collisions using Hadron Resonance Gas Model 7m
The study of light nuclei production in relativistic heavy-ion collisions provides valuable insights into the properties of the dense, hot medium produced in these collisions, which is assumed to mimic conditions of the early universe. In this work, we analyze the production of light (anti-)nuclei, such as $d$, $\bar{d}$, $t$, and $^3\text{He}$, in the framework of the Hadron Resonance Gas (HRG) model -- a theoretical approach that treats the hadronic phase as a gas composed of hadrons and their resonances. Following the approach of applying the nuclear equivalent of the Saha equation, we explore the evolution of light nuclei abundances post-chemical freeze-out, where disintegration and regeneration reactions are assumed to proceed in relative chemical equilibrium within the hadronic phase. Using the HRG model in Partial Chemical Equilibrium (PCE) available in the Thermal-FIST package, we study the sensitivity of light nuclei yields to temperature at the RHIC energies. The resulting predictions are compared with experimental data from the STAR Collaboration, offering a comprehensive understanding of the thermal properties and reaction kinetics in the expanding fireball.
Speaker: Dr Sabita Das (Kuntala Kumari Sabat Women's College)
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11:00 AM
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11:00 AM
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12:40 PM
Parallel C: QCD Phase Diagram. Chair: Sabyasachi Ghosh
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11:00 AM
The role of the pion mass on the QCD phase diagram in the $T-eB$ plane 13m
We investigate the effect of the pion mass on the quantum chromodynamics (QCD) phase diagram in the presence of an external magnetic field, aiming to understand it, for the first time, using Nambu\textendash Jona-Lasinio like effective models [1]. We compare results from both the local and nonlocal versions, finding that inverse magnetic catalysis (IMC) near the crossover is eliminated with increasing pion mass, while the decreasing trend of the crossover temperature with increasing magnetic field persists for pion mass values up to at least 440 MeV. Thus, the models are capable of capturing qualitatively the results found by lattice QCD (LQCD) for heavy (unphysical) pions. The key feature of these models is incorporating the reduction of the coupling constant with increasing energy. This not only reproduces the IMC effect but also describes the effects of heavier current quark masses without additional parameters. In the local NJL model, this agreement depends on parameter fitting at the physical point, whereas the nonlocal version naturally exhibits IMC effect around the crossover region, capturing the physics more naturally. We further use the nonlocal framework to determine the pion mass beyond which the IMC effect in the transition region no longer exists.
- Mahammad Sabir Ali, Chowdhury Aminul Islam and Rishi Sharma arXiv:2407.14449 [hep-ph]
Speaker: Dr Aminul Islam Chowdhury (Johann Wolfgang Goethe University) -
11:13 AM
Fluctuations and correlations of net-conserved quantities at LHC energies with ALICE 13m
Fluctuations and correlations of net-conserved quantities, including net-baryon, net-charge, and net-strangeness, are pivotal for exploring the QCD phase structure, as they are directly related to thermodynamic susceptibility ratios in lattice QCD (LQCD) calculations. These quantities probe the thermal properties of the medium and shed light on the nature of the strongly interacting matter created in high-energy nuclear collisions
We present results on second-order diagonal and off-diagonal cumulants of net-charge, net-proton, and net-kaon, with the net-proton and net-kaon serving as proxies for the net-baryon and net-strangeness number, respectively. The measurements are performed at mid-rapidity, as a function of centrality in Pb$-$Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV using data recorded by the ALICE detector. The results are compared with corresponding results at lower collision energies from the STAR experiment at RHIC, and with theoretical predictions from the HIJING, EPOS and Hadron Resonance Gas model (Thermal-FIST).
Recent lattice QCD studies have highlighted the significant impact of magnetic field ($eB$) on these thermodynamic susceptibility ratios. Interesting experimental results for observables that are claimed to be sensitive to initial magnetic field effects will also be discussed in this presentation.
Speaker: Swati Saha (National Institute of Science Education and Research (NISER) (IN)) -
11:26 AM
Induced electric field due to thermoelectric effects in an evolving quark-gluon plasma 7m
We have estimated the induced electric field in quark-gluon plasma (QGP) due to its thermoelectric effects. At present, the relativistic heavy-ion collisions are capable of creating QGP, a locally thermalized medium composed of quarks and gluons.
During the space-time evolution of the QGP medium, interesting thermoelectric phenomena occur due to the presence of electrically charged particles (quarks) in the QGP medium. These phenomena result in the generation of an electromagnetic (EM) field within the medium, even in central heavy-ion collisions. In peripheral collisions, the presence of a spectator current at the early stage generates a transient magnetic field and disrupts the isotropy of the induced electric field. For numerical estimation of the induced electric field, we used a quasiparticle-based model that incorporates the lattice quantum chromodynamics (lQCD) equation of state (EoS) for QGP. The cooling rates used in our calculations are derived from Gubser hydrodynamic flow, while the thermoelectric coefficients—such as Seebeck, magneto-Seebeck, and Nernst coefficients—are crucial for estimating the induced electric field. Furthermore, we explore the effects of an external time-varying magnetic field on the induced electric field and also consider the quantum effects of Landau quantization. Our findings reveal that the space-time profile of the induced electric field is zero at the center and increases away from the center. During the early stages of QGP evolution, the electric field can reach a maximum value of approximately $eE \approx 1~m_\pi^2$, which gradually weakens over time.Speakers: Kamaljeet Singh (Indian Institute of Technology Indore (IN)), Raghunath Sahoo (Indian Institute of Technology Indore (IN)) -
11:33 AM
Modelling Finite Volume Effects in the QCD Phase Diagram 7m
We investigate the impact of finite volume effects on the QCD phase diagram, particularly in the context of ultrarelativistic heavy ion collisions. Utilizing the Nambu-Jona-Lasinio (NJL) model, we analyze the chiral transition line in the (T, μB) plane with MIT boundary condition, simulating confinement within a fireball of limited dimensions. Our findings reveal that the transition temperature, number density, and its susceptibilities exhibit significant dependence on system volume. Notably, while the shift in the crossover transition line is modest, the first-order transition region displays pronounced volume sensitivity, particularly affecting the location of the critical point. These results underscore the necessity of accounting for finite size effects when interpreting experimental signatures of the QCD phase diagram, especially in light of ongoing and future low-energy experiments exploring regions of high baryonic density.
Speaker: Dr Adiba Shaikh (Tata institute of Fundamental Research (IN)) -
11:40 AM
Chiral cross-over in Hadron Resonance Gas model 13m
We investigate the behavior of the chiral condensate within a Hadron Resonance Gas model, incorporating repulsive mean-field interactions among baryons. By calibrating the strength of these interactions to match the lattice QCD estimations of higher-order baryon charge susceptibilities, we can extend this model to higher baryon densities, where lattice QCD encounters challenges due to the sign problem. Our analysis focuses on estimating the chiral pseudocritical line by studying the temperature dependence of the chiral condensate as a function of $\mu_B$. We describe the crossover line using a parametric form, $T_{pc}(\mu_B)/T_{pc}(0)=1-\kappa_2 (\mu_B/T_{pc} (0))^2-\kappa_4 (\mu_B/T_{pc} (0))^4$. Our findings yield $\kappa_2=0.0150(2)$ and $\kappa_4=3.1(6) \cdot 10^{-5}$. The agreement of $\kappa_2$ with lattice QCD results is excellent, and our study marks the first identification of a non-negligible $\kappa_4$ term within this context. Moreover, the separation between the freeze-out curve and the pseudo-critical line widens at higher densities, suggesting a prolonged hadronic phase at lower collision energies.
Speaker: Deeptak Biswas (National Institute of Science Education and Research (NISER)) -
11:53 AM
Studying liquid-gas phase transition under the effect of rotaion in a hadron resonance gas 7m
Understanding the phases of quantum chromodynamics (QCD) matter has become one of the important research areas for both theoretical and experimental high-energy physics community. In the QCD phase diagram, which is characterised by temperature ($T$) and baryochemical potential ($\mu_B$), a first-order phase transition is expected at high $\mu_B$ and low T, which ends at a possible critical point. This is followed by a crossover transition from hadron to quark matter as predicted by lattice QCD calculations. In addition to the magnetic field, a huge amount of vorticity is expected to be produced in a non-central heavy ion collision. This vorticity or rotation ($\omega$) can affect the evolution of the system and, hence, the phase diagram of the QCD matter. In this work, we study the effect of rotation on the phase diagram of hadronic matter. We find that rotation plays a similar role to baryochemical potential on the thermodynamic properties of hadron gas. The rotation adds a new kind of chemical potential called rotational chemical potential. Therefore, the phase transition can occur not only in the $T-\mu_B$ plane but also in the $T-\omega$ plane. We use an interacting hadron resonance gas model with van der Waals kind of attractive and repulsive interaction among the hadrons. We observe a liquid-gas phase transition under the effect of rotation, even at zero baryochemical potential. These results allow us to reinvestigate the QCD matter properties under the effect of rotation and study the phase diagram in the $T-\mu_B-\omega$ plane.
Speaker: Kshitish Kumar Pradhan (IIT Indore) -
12:00 PM
QCD Phase Diagram: QGP and Neutron Star Cores 7m
The proposed QCD Phase Diagram speculates deconfined Quark Matter at aymptotic high Temperature and Baryonic Densities. The region of QCD phase diagram characterized with low temperature and high baryonic density is been speculated to be found in the cores of neutron stars which are prone to phase transitions. The transition between the chiral and diquark condensate is being studied while reproducing some numerical results. The thermodynamic grand potential of system is minimized with respect to the order parameters m and ∆ to get the form of the gap equations. Using Numerical Techniques, we analyse these gap equations to study the strong competition between chiral and diquark condensate in the 2 Flavour Superconducting Phase. The region of QCD phase diagram characterized with high temperature and low baryonic density corresponds to early stage of universe. Quark-Gluon plasma (QGP) under a statistical model is revisited. While revisiting some additional parameters having consider to compute the thermodynamic properties of the QGP. Hence the results after considering new parameters are compared with the earlier results.
Speaker: Mr Vibhor Khanna (IISER Thiruvananthapuram) -
12:08 PM
Investigations of event-by-event fluctuations of mean transverse momentum ($\langle p_{\rm T} \rangle$) in pp collisions at $\sqrt{s}$= 13 TeV with PYTHIA8 and HERWIG7 models 7m
The study of event-by-event mean transverse momentum ($\langle p_{\rm T} \rangle$) fluctuations is reported in terms of the integral two-particle correlator ($\langle \Delta p_{\rm T} \Delta p_{\rm T}\rangle$) and skewness of the event-wise $\langle p_{\rm T} \rangle$ distribution in proton$-$proton (pp) collisions at $\sqrt{s}=13$ TeV. The simulations were carried out using the Monte Carlo event generators PYTHIA8 and HERWIG7. Charged particles with transverse momentum ($p_{\rm T}$) and pseudo-rapidity ($\eta$) ranges $0.15 \leq p_{\rm T}\leq 2.0$ GeV/$c$ and $|\eta| \leq 0.8$ were taken into the consideration. The correlator $\langle \Delta p_{\rm T} \Delta p_{\rm T}\rangle$ is observed to follow distinct declining trends with the average charged particle multiplicity ($\langle N_{\rm ch} \rangle$) for PYTHIA8 and HERWIG7 models. Furthermore, both models yield positive finite skewness in low-multiplicity events. The observables are additionally studied using the transverse spherocity estimator ($S_{\rm 0}$) to comprehend the relative contributions of hard scattering (jets) and soft multi-partonic interactions (MPI) to the observed fluctuations. The comparative measurements using these models would help in understanding the fluctuation dynamics and constraint the particle productions in such models.
Speaker: Subhadeep Roy (IIT- Indian Institute of Technology (IN)) -
12:15 PM
Higher order cumulants of net-particle distributions in pp collisions at $\sqrt{s}$ = 13 TeV using Pythia and Herwig 7m
Higher order cumulants of the distributions of conserved quantities, like net-charge, net-baryon and net-strangeness in heavy-ion collisions, are regarded as sensitive observables to determine the freeze-out parameters and the nature of phase transitions at the LHC energies. Recently, several experimental results suggest the possible formation of QGP medium in high-multiplicity pp collisions. Therefore, baseline measurements of the higher order cumulants of the net-particle distributions in pp collisions are essential to compare with the experimental results for understanding the dynamics of small systems. In this work, we report the first and a detailed Monte-Carlo study of the measurements of cumulants and their ratios for net-charge, net-hadron, net-kaon, net-baryon, and net-proton distributions in pp collisions at $\sqrt{s}$=13 TeV using pQCD models like Pythia8 and Herwig. We also discuss the effect of different particle production mechanisms, kinematic acceptance, and volume fluctuations on higher-order cumulants. This simulation study will serve as a baseline for the upcoming measurements at the LHC. Additionally, it will shed more light on the measurement of cumulants and the connection between small systems and heavy-ion collisions at the LHC.
Speaker: Nirbhay Kumar Behera (Central University of Tamil Nadu, Thiruvarur, India) -
12:22 PM
Understanding flavor mixing from the curvature of chiral crossover line 13m
Using a $(2+1)$-flavor Nambu--Jona-Lasinio (NJL) model, we study the effects of the strangeness chemical potential ($\mu_{S}$) and vector interactions on the chiral crossover lines, which we then use to examine flavor mixing within this framework. With the curvature coefficients, $\kappa_{2}$'s, showing excellent agreement with available lattice QCD (LQCD) findings, we estimate the permissible strength of various types of vector interactions. A key finding is that $\kappa_{2}^{B}$ exhibits a nontrivial decreasing trend with increasing $\mu_{S}$, eventually becoming negative at sufficiently high $\mu_{S}$. This behavior strongly depends on flavor mixing due to the $U(1)_A$-breaking 't Hooft interaction and vector interaction. We propose this unique trend as a valuable metric for quantifying flavor mixing in both NJL-like models and QCD, advocating for further exploration of this effect in LQCD.
Speaker: Dr Mahammad Sabir Ali (National Institute of Science Education and Research)
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11:00 AM
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11:00 AM
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12:40 PM
Parallel D: Hard probes, heavy flavor Chair: Min Jung Kweon
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11:00 AM
Open Quantum System approaches for quarkonium evolution in the QGP 18m
This is a mini-review talk.
Speaker: Rishi Sharma -
11:18 AM
Prompt and non-prompt production of charm hadrons in proton-proton collisions at the Large Hadron Collider using machine learning 18m
The studies of heavy flavor (charm or bottom) hadrons in relativistic collisions provide an undisputed testing ground for the theory of strong interactions, quantum chromodynamics (QCD). As the majority of the heavy flavor particles are produced in the initial stages of the heavy-ion collisions, they experience the whole QCD medium evolution. The lightest open charm meson, $D^{0}$, and hidden charm vector meson, J/$\psi$, are particularly useful as they are abundantly produced as compared to other open and hidden charm hadrons, respectively. The $D^{0}$ and J/$\psi$ mesons that are either directly formed during initial scattering or as the decay products of higher charm stages are referred to as the prompt production, which is essential to probe the QCD medium. On the other hand, the non-prompt $D^{0}$ and J/$\psi$ mesons are usually formed as the decay products of beauty hadrons and can provide a key understanding of beauty hadrons.
In this contribution, we use machine learning (ML) models to segregate the prompt and non-prompt productions of $D^{0}$ and J/$\psi$ mesons in proton-proton (pp) collisions at $\sqrt{s}=13$ TeV using the
track-level information of the particles like an experimental environment. We have used the PYTHIA8 event generator to simulate the events for the study, which provides a good qualitative description of experimental measurements. We have considered the $D^{0}\rightarrow\pi^{+}K^{-}$ and J/$\psi\rightarrow\mu^{+}\mu^{-}$ decay channels for our study. To separate prompt from non-prompt sector of charmonia and open charm mesons, topological production of $D^{0}$ and J/$\psi$ are considered. We have used XGBoost, CatBoost, and Random Forest models for $D^{0}$ related studies, whereas for J/$\psi$, we have used XGBoost and LighGBM models. For $D^{0}$, we have used invariant mass ($m_{\pi K}$ ), pseudoproper time ($t_z$ ), pseudoproper decay length ($c_{\tau}$ ), and distance of closest approach ($\rm{DCA}_{D_{0}}$ ) as the training inputs. For J/$\psi$ meson, the input sample is chosen keeping ALICE Run 3 muon forward tracker upgrade in mind, which includes, invariant mass ($m_{\mu\mu}$ ), transverse momentum, pseudorapidity, and $c_{\tau}$. The machine learning models provide up to 99\% accuracy to dissect the prompt and non-prompt production of both $D^{0}$ and J/$\psi$. Transverse momentum, rapidity and multiplicity differential comparisons between the true and predicted values are compared to evaluate the performance of the models. Experimental comparisons are also made wherever applicable. The ML methods used in the present study can replace the traditionally used fitting method with the added advantage of track label identification. The present ML-based identification of prompt and non-prompt charm hadrons can be useful in experiments that require precise measurements.Speaker: Raghunath Sahoo (Indian Institute of Technology Indore (IN)) -
11:36 AM
Understanding of quarkonia production in forward rapidity region 13m
Due to the heavy-quark symmetry of Non-Relativistic Quantum Chromodynamics (NRQCD), the cross-section for the production of $\eta_c$ can be predicted. This NRQCD prediction when confronted with data from the LHCb is seen to fail miserably. However, modified NRQCD provides a neat solution to the LHCb $\eta_c$ anomaly and provides an understanding of all the features of the $\eta_c$ data. Furthermore, we compare the recent LHCb data for the integrated cross-section of $h_c$ production at $\sqrt{s}$ = 13 TeV in the kinematic range 5.0 $<$ $p_T$ $<$ 20.0 GeV and 2.0 $<$ $y$ $<$ 4.0 with the theoretical predictions using NRQCD and modified NRQCD. Modified NRQCD gives an agreement with the recent LHCb experimental data.
Motivated by the success of modified NRQCD, we have extended
the work to study charmonia production in the forward rapidity region.Speaker: Sushree S. Mishra -
11:49 AM
Observation of asymmetric jet shape in a longitudinally boosted flowing medium in PbPb collisions with CMS 7m
The interactions between jets and the longitudinal-boosted quark-gluon plasma (QGP) lead to softer particles drifting away from the jet core, where high-$p_\mathrm{T}$ particles remain concentrated, resulting in an intra-jet asymmetry. Investigating this asymmetry, particularly at forward rapidities, offers a novel avenue to probe jet-medium dynamics. Using the PbPb and pp data at $\sqrt{s_{{\mathrm{NN}}}} = 5.02$ TeV collected by the CMS detector, the near-side jet peak of two-particle correlation functions have been examined to explore jet modifications and novel boost invariance phenomena in forward rapidity. The peak exhibits substantial broadening along the longitudinal ($\Delta\eta$) axis from peripheral to central PbPb collisions, indicating energy loss by the progenitor parton. A significant rapidity-dependent asymmetry in associated particle yields has been observed for the first time, with a pronounced difference between $\Delta\eta > 0$ and $\Delta\eta < 0$ that increases at forward rapidity and in central PbPb collisions. This finding, particularly evident for high-$p_\mathrm{T}$ particles, points to a potential violation of boost invariance at forward rapidity. Comparisons with different theoretical models will be discussed to understand the influence of jet-medium interactions on jet structure.
Speaker: Sayan Chatterjee (Indian Institute of Technology Madras (IN)) -
11:56 AM
Possibility of charm diffusion in an interacting hadronic matter 7m
We estimate the diffusion coefficient matrix for baryon number, strangeness, electric charge, and charm quantum numbers in an interacting hadron gas. For the first time, this study provides insights into the charm current and estimates the diffusion matrix coefficient for charmed states, treating them as part of a quasi-thermalized medium. We analyze the diffusion matrix coefficient as a function of temperature and center-of-mass energy, assuming van der Waals-like interactions among hadrons, which include both attractive and repulsive forces. The diffusion coefficients are determined using the relaxation time approximation to the Boltzmann transport equation, showing good agreement with existing model calculations in the hadronic regime. We observe that at low $\sqrt{s_{NN}}$, hadrons carrying conserved charges such as baryon number ($B$), electric charge ($Q$), and strangeness ($S$) diffuse more rapidly compared to charmed hadrons. As a result, charm fluctuations generated in the early stages of heavy-ion collisions remain significant until freeze-out. In experiments, the net proton number cumulants are typically used as a proxy for net baryon fluctuations. However, the greater diffusion of baryons could lead to a smearing of the critical point signal. Thus, we propose using net charm number fluctuations as a new probe to locate the QCD critical point.
Speakers: Kangkan Goswami (Indian Institute of Technology Indore), Raghunath Sahoo (Indian Institute of Technology Indore (IN)) -
12:03 PM
Cold nuclear matter effects on charmonium production in fixed target proton-nucleus collisions 7m
Charmonia ($c\bar{c}$) states are believed to undergo considerable suppression, if quark-gluon plasma (QGP) is formed relativistic heavy-ion collisions. However a precise identification of the "anomalous" suppression pattern and its interpretation as a signature of color deconfinement, demands a detailed understanding of charmonium production and suppression in proton-nucleus ($p+A$) collisions. In these collisions charmonium production is affected due to the presence of several different effects inside the target nucleus, collectively known as cold nuclear matter (CNM) effects resulting an increase in production cross section less than linearly with the number of target nucleons. In the foreseen contribution we plan to make detailed evaluation of the different CNM effects, namely initial state parton energy loss, nuclear shadowing and final state absorption of the nascent $c\bar{c}$ pairs in their pre-resonance or resonance stage by analyzing the available data on charmonium production in fixed target $p+A$ collision experiments from SPS, Fermilab and HERA-B. Extrapolating the observed pattern we give a prediction of the level of "normal" absorption in the upcoming experiments NA60+ at CERN SPS and CBM at FAIR.
Speaker: Sourav Kanti Giri (Department of Atomic Energy (IN)) -
12:10 PM
Open heavy-flavour hadron decay muon production with ALICE at the LHC 13m
The measurements of heavy-flavour (charm and beauty) production in proton-proton (pp) collisions at the LHC provide stringent test for perturbative Quantum Chromodynamics (pQCD) calculations. Furthermore, studies in pp collisions serve as a necessary baseline for similar measurements in proton-nucleus (p-A) and nucleus-nucleus (A-A) collisions in order to investigate the influence of cold- and hot-nuclear-matter effects on heavy-flavour production. In ALICE, measurements of open heavy-flavour can be performed at midrapidity and forward rapidity via semi-electronic and semi-muonic decays of heavy-flavour hadrons, respectively. The presence of Muon Forward Tracker in the upgraded ALICE detector for the LHC Run 3 provides vertexing capabilities to the Muon Spectrometer and enables to separate the open charm and beauty components. The impact of the medium formed in heavy-ion collisions on heavy quark production and dynamics can be quantified via the nuclear modification factor ($R_{\rm{AA}}$) of muons from heavy-flavour hadron decays. The results in the measurement of $R_{\rm{AA}}$ point toward a significant heavy-quark energy loss at intermediate $p_{\rm{T}}$. In this contribution, the latest measurements from Run 2 and the status from Run 3 of open heavy-flavour decay muon production at forward rapidity with ALICE will be presented.
Speaker: Dr Md Samsul Islam (Indian Institute of Technology Bombay) -
12:23 PM
Quarkonium polarization measurement in hadronic and nuclear collisions at forward rapidity 7m
Quarkonium production in ultra-relativistic collisions is an essential probe for understanding the deconfined phase of QCD matter. Further, quarkonium suppression in heavy-ion collisions supports the existence of the deconfined, thermalized, and strongly interacting QCD medium known as quark-gluon plasma (QGP). However, phenomena like collective flow, which is assumed to be another crucial feature of QGP, have been recently observed in relativistic pp collisions at the LHC energies. As pp lacks the baseline, the measurement of quarkonium suppression becomes infeasible in the conventional way. However, polarization measurements of quarkonium states may serve as a baseline-independent probe for investigating the QGP medium because it depends on the shape of the angular distribution of dileptons along a quantization axis. Analyzing quarkonium polarization in these collisions constrains the underlying production mechanisms and sheds light on the formation of bound states. Recently, the finite spin alignment of J/ψ in Pb-Pb collisions at $\sqrt{s}_{NN}$ = 5.02 TeV advocates the possible existence of spin-vorticity coupling in thermally rotating media [1]. Although a range of sources could potentially contribute to this phenomenon, it is assumed that the primary contribution arises due to the vorticity field, electromagnetic field and the strong vector meson force field. In this presentation, we summarize the quarkonium polarization measurement obtained so far using the muon spectrometer of ALICE at forward rapidity in Pb-Pb and pp collisions at LHC energies for helicity, Collins-soper and the event plane frames [1-4]. Additionally, the comparison of various theoretical model predictions with respect to experimental observation will be presented. With the help of newly built Muon Forward Tracker the precise measurements of quarkonia polarization in hadronic and nuclear collisions along with the separation of prompt and non-prompt quarkonium states can be performed using the high statistics Run 3 data.
Speaker: Bhagyarathi Sahoo (Indian Institute of Technology Indore (IN)) -
12:30 PM
NON-PERTURBATIVE HEAVY QUARK DIFFUSION IN A WEAKLY MAGNETIZED THERMAL QCD MEDIUM 7m
Heavy quarks (HQ) are considered to be excellent probes of the hot QCD matter produced in the high-energy heavy-ion collisions. HQ diffusion coefficient is one of the fundamental transport properties of the hot QCD matter. In this work, we have calculated the HQ momentum ($\kappa$) as well as spatial ($D_s$) diffusion coefficients in an ambient background weak magnetic field via evaluating the scattering rate of HQ's with light thermal partons. To that end, we calculate the HQ self-energy in the presence of a weak magnetic field by using the HQ potential as a proxy for the resummed gluon propagator. The information about the magnetic field comes in via the HQ potential, wherein, the light thermal partons are assumed to occupy all Landau levels. In this potential formulation, one can consider a non-perturbative ansatz for the gluon propagator which produces a string-like confining effect in coordinate space, thus allowing for the calculation of non-perturbative contribution to the HQ transport coefficients. We have computed the heavy quark diffusion coefficients at both zero and finite momentum, observing that non-perturbative effects play a dominant role at low momentum and low temperature. Our spatial diffusion coefficient, $2\pi T D_s$, shows good agreement with recent LQCD results. These findings can be used to calculate the heavy quark directed flow at RHIC and LHC energies.
Speaker: Dr Debarshi Dey (Indian Institute of Technology Bombay)
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11:00 AM
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12:40 PM
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2:10 PM
Lunch
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2:10 PM
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4:18 PM
Parallel A: Theoretical developments. Chair: Amaresh Jaiswal
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2:10 PM
Relativistic Hydrodynamics - A causality-stability perspective 18m
Relativistic Hydrodynamics - A causality-stability perspective
Speaker: Sukanya Mitra -
2:28 PM
Effects of collision dynamics on p$\phi$ femtoscopy 18m
Femtoscopy in high-energy nuclear collisions is a novel phenomenological tool to study low-energy hadron interactions, and active studies in the past decade have demonstrated its usefulness [1]. Thus, hadron interaction study via femtoscopy is now advancing to unravel less understood interactions, such as baryon-vector meson interactions. However, since existing studies have assumed simple static Gaussian source functions, the influence of collision dynamics and kinematics has not yet been fully understood.
In this study, we utilized a state-of-the-art dynamical model, DCCI [2], to investigate the influence of collision dynamics and kinematics on the p$\phi$ correlation function in high-multiplicity p+p collisions. Regarding p$\phi$ femtoscopy, a recent study using a Gaussian source [3] indicated the possible existence of a bound state from the ALICE correlation data. We reanalyzed the correlation function using DCCI and found that the collision dynamics, such as collectivity and hadronic rescattering, leads to a non-Gaussian momentum-dependent source [4]. Consequently, the correlation function slightly differs from that obtained using a Gaussian source. This emphasizes the importance of considering collision dynamics and kinematics for future high-precision femtoscopic studies.
[1] L. Fabbietti et al., Ann. Rev. Nucl. Part. Sci. 71, 377 (2021).
[2] Y. Kanakubo, Y. Tachibana, T. Hirano, Phys. Rev. C 105, 024905 (2022).
[3] E. Chizzali et al., Phys. Lett. B 848, 138358 (2024).
[4] K. Kuroki, T. Hirano, arXiv:2410.01204 [hep-ph].Speaker: Kenshi Kuroki -
2:46 PM
Shear and bulk viscosity for a pure glue theory using an effective matrix model 13m
At nonzero temperatures, the deconfining phase transition can be analyzed using an effective matrix model to characterize the change in holonomy. The model includes gluons and two-dimensional ghost fields in the adjoint representation, or "Teens". As ghosts, the teen fields are responsible for the decrease of the pressure as $T \rightarrow T_d$, with $T_d$ the transition temperature for deconfinement. Using the solution of this matrix model for a large number of colors, the parameters of the teen fields are adjusted so that the expectation value of the Polyakov loop is close to the values from the lattice. The shear, $\eta$, and bulk, $\zeta$, viscosities are computed in weak coupling but nonzero holonomy. In the pure glue theory, the value of the Polyakov loop is relatively large in the deconfined phase, $\approx 1/2$ at $T_d$. Consequently, if $s$ the entropy density, while $\eta/s$ decreases as $T\rightarrow T_d$, it is still well above the conformal bound. In contrast, $\zeta/s$ is largest at $T_d$, comparable to $\eta/s$, then falls off rapidly with increasing temperature and is negligible by $\sim 2 T_d$.
Speaker: Manas Debnath (National Institute of Science Education and Research, Bhubaneswar) -
2:59 PM
Chaos and thermalization in SU(2) gauge theory under in- and out-of-equilibrium conditions 13m
We measure the Lyapunov exponent in SU(2) gauge theory under both in and out-of-thermal equilibrium conditions to understand the chaotic nature of non-Abelian gauge theories and its implications. Very close to the deconfinement temperature $T_c$, we use the fact that $SU(2)$ gauge theory falls within the same universality class as a $Z_2$ scalar field theory and calculate the Lyapunov exponent using out-of-time-ordered correlation (OTOC) function constructed out of the scalar fields. On the other hand in a high temperature ($T>>T_c$) thermal plasma, where the hard, electric and magnetic scales are well separated, we measure the Lyapunov exponent within the effective Hamiltonian theory of the soft gauge fields (magnetic modes). For measuring the degree of chaoticity from the Lyaponov exponent we consider a particular out-of-equilibrium state of SU(2) which describes a classical fixed point of the Hamiltonian evolution of the gauge fields and exhibit self-similar scaling. Such a state is obtained through classical evolution of gauge fields whose infrared momentum modes are over-occupied, and shows similar separation of hard and soft scales similar to a thermal plasma. We show that such a state is also chaotic. By calculating the Lyapunov exponent in this non-equilibrium state and comparing with its corresponding values at similar energy density in a thermalized SU(2) plasma we provide an estimate of the equilibration time. Our study can provide some insights about the thermalization time of the non-Abelian plasma formed in the heavy-ion collisions.
Speaker: SAYAK GUIN (The Institute of Mathematical Sciences, Chennai, India) -
3:12 PM
Understanding properties of the Dirac eigenspectrum in QCD and approach to thermalization 13m
In this work, we study the localization properties of the eigenstates of non-Abelian SU(3) gauge theory both with and without dynamical quark flavors in a gauge invariant manner, using first-principles lattice gauge theory techniques. We use the eigenspectrum of a probe (overlap) Dirac operator to understand the properties of thermal gauge ensembles of 2+1 flavor QCD generated using domain wall fermions as well as pure SU(3) gauge theory. Focusing on the infrared part of eigenspectrum that lie within the non-perturbative magnetic scale, we propose suitable observables that allow us to unambiguously categorize different regions of the eigenspectrum. While most of these so-called magnetic modes are completely delocalized and chaotic, with nearest-neighbor level spacing fluctuations similar to random matrices of a Gaussian unitary ensemble (GUE), few eigenmodes with fractal-like properties start to appear at temperatures just near and above the chiral crossover temperature. We show that their fractal dimensions carry information about the universality class of the chiral transition in QCD.
Having demonstrated that at sufficiently high temperatures, the non-Abelian plasma is gluon dominated with large occupation numbers in the infra-red and exhibits properties similar to a chaotic system, we discuss its consequences for heavy-ion experiments. Starting from a non-equilibrium initial state of SU(3) gluons inspired by the Color
Glass Condensate effective theory, a real-time classical-statistical evolution leads to a self-similar scaling regime where we show that infrared magnetic modes are also over-occupied and chaotic. Thus by matching the evolving magnetic scale in this non-equilibrium scaling regime with that of a typical thermal state of QCD, we estimate a thermalization time of $\sim 1.44$ fm/c.
Reference: Understanding the approach to thermalization from the eigenspectrum of non-Abelian gauge theories, Harshit Pandey, Ravi Shanker, Sayantan Sharma, arXiv:2407.09253 [hep-lat]Speaker: Ravi Shanker (The Institute of Mathematical Sciences) -
3:25 PM
Quantum Hall effect for quarks in chiral effective model 7m
A net baryon density up to 2-6 times the nuclear saturation density and high magnetic fields are expected in the reaction zone of upcoming CBM/NICA experiments. Such densities are also likely in the core of massive neutron stars, possibly with mixed quark-hadron phases. The chiral effective model, based on the principles of chiral symmetry breaking and broken scale invariance, is employed to incorporate the in-medium effects of constituent quarks within hadrons. The classical and quantized versions of electrical conductivity and resistivity are studied in the relaxation time approximation framework of kinetic theory. Anisotropic electrical conductivity and resistivity tensors are investigated by considering cyclotron motion and Landau quantization. In the presence of strong magnetic fields, the Landau quantization of perpendicular momenta results in quantized anisotropic transport coefficients of the system. Two interesting macroscopic manifestations of Landau quantization are the Shubnikov-de Haas (SdH) oscillations and the Quantum Hall Effect (QHE) [1]. In this work, we explore the possibility of SdH/QHE type oscillations in low temperature and high magnetic field conditions present in the interior of the dense neutron stars, as well as in future facilities of CBM/NICA experiments. Finally, we also present a quantitative estimate of the same in the interior of a neutron star where the magnetic field varies as a function of the baryon density.
References
[1] Dey, J., Bandyopadhyay, A., Gupta, A., Pujari, N., & Ghosh, S. (2023). Electrical conductivity of strongly magnetized dense quark matter-possibility of quantum Hall effect. Nuclear Physics A, 1034, 122654.Speaker: Dani Rose J Marattukalam (Indian Institute of Technology Bhilai) -
3:32 PM
Heavy quark potential in anisotropic medium 7m
In this work, the real part of the static potential of a heavy quark-antiquark system in an anisotropic plasma medium is studied. The collective dynamics of the plasma constituents is described using hard-loop perturbation theory. The distribution function of the medium is characterized by a general set of anisotropy parameters. We calculated the real part of the heavy quark potential numerically and studied the angular dependence of the distortion of the potential relative to the isotropic one. Our study suggests that plasma anisotropy plays an important role in the dynamics of heavy quarkonium.
Speaker: Arghya Mukherjee -
3:39 PM
Sensitivity of jets to initial stages 18m
Sensitivity of jets to initial stages
Speaker: Dr Souvik Priyam Adhya (Institute of Physics of the Czech Academy of Sciences) -
3:57 PM
Exploring Hyperon Properties in Dense Baryon Matter and Neutron Stars 7m
We examine the properties of hyperons (Λ, Σ, Ξ) in dense baryon matter and neutron stars using a modified relativistic Dirac formalism (MRDF). In this approach, the quark meson (σ, ω) couplings are derived self-consistently at the quark level, where quark confinement is modelled through a scalar-vector linear potential, and corrections are incorporated for centre-of-mass motion, one-gluon exchange, and pionic contributions. We start by calculating the masses of baryons in a vacuum and then proceed to evaluate them within a medium. This work examines the properties of baryon matter, “such as the equation of state, compressibility, binding energy, and pressure. In addition, we compute essential parameters, including the baryon charge radius, axial-vector coupling constant, pion coupling constant, baryon sigma term, symmetry energy, density slope (L), and incompressibility (K₀)”.
Speaker: Akash Kumar Jena (Berhampur University) -
4:04 PM
Enhanced $\psi^{\prime}$ yield and $\psi^{\prime}/(J/\psi)$ yield ratio, a signature of QGP formation in high multiplicity $p+p$ collisions 7m
Suppression in the yield of quarkonia (heavy quark-antiquark bound states) has been considered one of the important signatures of the formation of the thermalized deconfined partonic matter, also known as the Quark Gluon Plasma (QGP), in Relativistic Heavy Ion Collision Experiments (RHICE). Traditionally, the in-medium dissociation of quarkonium states has been presented by implicitly assuming an adiabatic approximation, which considers that the heavy quark Hamiltonian changes slowly over time owing to change in the medium. However, in high multiplicity smaller systems, such as in $p+p$ collisions, the early development of transverse flow resulting from the finite transverse size of the locally thermalized medium may cause the quarkonium states to undergo a non-adiabatic evolution. It has been argued that in the presence of such a non-adiabatic evolution, the suppression of heavy quark-antiquark bound state yields may not reliably indicate QGP formation~\cite{Bagchi:2023vfv}. We propose that, rather than
concentrating on the suppression of $J/\psi$ yields, the enhancement in the yield ratio of $\psi^{\prime}$ to $J/\psi$ (i.e., $\psi^{\prime} / (J/\psi)$), along with an increase in $\psi^{\prime}$ yield, should be considered as a probe of QGP formation for small systems. Our findings, based on realistic modeling of the time evolution of small systems, suggest that the yield ratio $\psi^{\prime} / (J/\psi)$ and the yield of $\psi^{\prime}$ increase as a function of hydrodynamization temperature incorporating the non-adiabatic transitions in high multiplicity $p+p$ collisions.Speaker: Ananta P. Mishra (NISER) -
4:11 PM
On the convergence of the gradient expansion of the Boltzmann equation 7m
When two heavy nuclei collide in relativistic heavy ion collisions, the resulting
system is initially in a non-equilibrium state. The evolution of the system
towards equilibrium can be studied by using the Boltzmann equation.
However, approximating the solution to the Boltzmann equation using a
gradient expansion leads to a divergent series. Using an integral solution to
the Boltzmann equation in relaxation time approximation, we obtain its full
gradient expansion which contains exponentially decaying non-hydrodynamic
terms. It is shown that this gradient expansion can have a finite radius of
convergence. We further argue that, in the relaxation time model, proximity
to local thermal equilibrium is not necessary for the system to be described by
hydrodynamic equations.Speaker: Reghukrishnan Gangadharan
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2:10 PM
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2:10 PM
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4:17 PM
Parallel B: Collectivity. Chair: Raghunath Sahoo
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2:10 PM
Lambda directed flow for validating the Lambda potential from chiral EFT: Bridging heavy-ion collisions, hypernuclei, and neutron stars 18m
We investigate the validity of the $\Lambda$ single-particle potential ($\Lambda$ potential) in dense matter that is based on chiral effective field theory (chiral EFT) that is sufficiently repulsive to solve the hyperon puzzle of neutron stars. We discuss that the model calculations with the $\Lambda$ potential are consistent with the $\Lambda$ hypernuclear spectroscopy [1] and the $\Lambda$ directed flow $v_1$ [2] in heavy-ion collisions.
A unified approach integrating heavy-ion collisions, other nuclear experiments, and neutron stars with the modern nuclear force from chiral EFT has provided valuable insights into the properties of the equation of state (EOS) of dense matter (e.g. Ref. [3]). This approach contributes to a more comprehensive understanding of both nuclear experiments and astrophysical observations. For a microscopic description of dense matter, such an approach must be performed also for the hyperon sector. A precise understanding of the hyperon potentials in nuclear matter is essential for addressing the long-standing hyperon puzzle of neutron star physics.
In this talk, we consider the $\Lambda$ directed flow $v_1$ [2] at RHIC-BES energies to verify the $\Lambda$ potential based on chiral EFT [4]. This potential is sufficiently repulsive at high densities to solve the hyperon puzzle and has proven by us to be consistent with the $\Lambda$ hypernuclear spectroscopy [1]. We employ a relativistic quantum molecular dynamics (RQMD) implemented into the Monte-Carlo event generator JAM2. We show that the model with the $\Lambda$ potential from chiral EFT can reproduce the experimental data [2], while a more attractive $\Lambda$ potential also reproduces the data. Thus, additional constraints on the Λ potential are demanded.
[1] A. Jinno, K. Murase, Y. Nara, and A. Ohnishi, Phys. Rev. C 108 (2023) 065803.
[2] Y. Nara, A. Jinno, K. Murase, and A. Ohnishi, Phys. Rev. C 106 (2022) 044902.
[3] S. Huth, et al., Nature 606 (2022) 276.
[4] D. Gerstung, N. Kaiser, and W. Weise, Eur. Phys.J. A 56 (2020) 175.Speaker: Asanosuke Jinno -
2:28 PM
Selected results from isobar collisions at RHIC 13m
Recent experiments involving isobar collisions of $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr have been carried out at the Relativistic Heavy Ion Collider (RHIC). These studies aim to explore various phenomena, including the initial conditions of the collision process, baryon stopping, the chiral magnetic effect, and collective flow, which are all essential for understanding the dynamics of heavy-ion collisions. Although the two nuclei have the same mass number, understanding the differences between their isobar collisions is valuable for exploring nuclear structure and deformation.
In this talk, we will discuss selected measurements related to particle production, collective flow, and the chiral magnetic effect of charged and identified hadrons at mid-rapidity for Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV. The dependence of the transverse momentum ($p_{T}$) for various centrality intervals will be shown. Additionally, system size dependence will be explored by comparing the results in isobar collisions with those from Cu+Cu, Au+Au, and U+U collisions. Furthermore, experimental results will be compared with transport model calculations to provide insight into the nuclear structure of the isobars.
Speaker: Dr Vipul Bairathi (Instituto de Alta Investigación, Universidad de Tarapacá) -
2:41 PM
Azimuthal anisotropic flow measurements in Au+Au collisions using RHIC BES-II data 7m
One of the objectives of the STAR experiment is to study the phase transition from hadronic matter to Quark Gluon Plasma (QGP). This can be investigated by studying the collective flow of various particle types produced in heavy-ion collisions, particularly by testing whether the number of constituent quark (NCQ) scaling holds or breaks across different energies. Specifically, the elliptic ($v_2$) and triangular ($v_3$) flow coefficients, which represent second- and third-order azimuthal anisotropies in particle momentum distributions, provide insights into the equation of state and transport properties of the medium, the shear viscosity to entropy density ratio ($\eta/s$).
Recently, STAR completed data taking for the Beam Energy Scan phase-II (BES-II) with upgraded detector capabilities and extended rapidity coverage. In this presentation, we will showcase high-precision measurements of $v_{2}$ and $v_{3}$ for various identified hadrons, including $\pi^{+}(\pi^{-})$, $K^{+} (K^{-})$, $p(\bar{p})$, $K_{S}^{0}$, $\phi$, $\Lambda(\bar{\Lambda})$, $\Xi^{-}(\bar{\Xi}^{+})$, and $\Omega^{-}(\bar{\Omega}^{+})$, from Au+Au collisions at $\sqrt{s_{NN}}$= 3.0-19.6 GeV. The results will cover the centrality and transverse momentum dependence as well as the NCQ scaling of $v_{n}$. Finally, we will discuss the implications of these measurements in understanding onset of partonic collectivity.
Speaker: Prabhupada Dixit -
2:48 PM
Exploring the flow harmonic correlations via multi-particle symmetric and asymmetric cumulants in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV 7m
We study multi-particle azimuthal correlations in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. We use initial conditions obtained from a Monte-Carlo Glauber model and evolve them within a viscous relativistic hydrodynamics framework that eventually gives way to a transport model in the late hadronic stage of the evolution. We compute the multi-particle symmetric and asymmetric cumulants and present the results for their sensitivity to the shear and bulk viscosities during the hydrodynamic evolution. We also check their sensitivity to resonance decay and hadronic interactions. We demonstrate that while some of these observables are more sensitive to transport properties than traditional flow observables, others are less sensitive, making them suitable for studying different stages of the evolution.
Speaker: Mr Kaiser Shafi (Indian Institute of Science Education and Research, Berhampur) -
2:55 PM
Longitudinal spin polarization with dissipative corrections 7m
In this work, we address the problem of longitudinal spin polarization of Λ hyperons produced in relativistic heavy-ion collisions. We employ a relativistic kinetic theory framework that incorporates spin degrees of freedom treated classically, combined with the freeze-out parametrization used in previous investigations. This approach allows us to include dissipative corrections—stemming from thermal shear and gradients of thermal vorticity—into the Pauli-Lubanski vector, which determines spin polarization and can be directly compared with experimental data. As in similar studies, we find that successfully describing the data requires additional assumptions. In our case, these involve using projected thermal vorticity and suitably adjusting the spin relaxation time (τ_s). From our analysis, we determine that τ_s ≈ 5 fm/c, which is comparable to other estimates. We also present our progress on numerical simulations.
Speaker: Soham Banerjee -
3:02 PM
Bose-Einstein correlations of charged hadrons in RHIC and LHC energies 7m
In proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV, gold-gold collisions at energies ranging from $\sqrt{s}$ = 7.7 GeV to 200 GeV, and lead-lead collisions at 2.76 TeV and 5.02 TeV, Bose-Einstein correlations of charged hadrons are examined across the entire multiplicity spectrum of reconstructed charged particles. The CMS data are then compared with results from proton-proton collisions at $\sqrt{s}$ = 13 TeV. Computational data are generated using two theoretical models, AMPT and PYTHIA 8. In the case of PYTHIA 8, data are produced under conditions with and without Bose-Einstein correlations. For AMPT, data are generated under conditions with and without string melting.
Speaker: Mohammad Mondal (Tata Institute of Fundamental Research (IN)) -
3:09 PM
Energy and baryon emission surfaces in relativistic heavy ion collisions via HBT Correlations 7m
The Hanbury Brown-Twiss (HBT) interferometry technique uses the two-particle correlation function to extract the three HBT radii, which measure the spatial and temporal dimensions of the particle emission source at freeze-out in heavy-ion collisions. In this study, we have employed a hybrid model combining hydrodynamic evolution with hadronic transport to simulate the collision dynamics in the presence of QCD conserved charges, most importantly the baryons. We investigate the possibility of accessing the emission sources of energy and baryon via meson-baryon-antibaryon splitting in the HBT radii that offer a unique insight into the freezeout processes and through that into their respective initial conditions.
Speaker: Mr Arkadip Mukherjee (IISER Berhampur) -
3:16 PM
Dependence of directed flow on system size and net conserved charges from quark coalescence in heavy-ion collisions 13m
The properties of the QGP medium produced in relativistic heavy-ion collisions can be explored using the directed flow ($v_{1}$) of the azimuthal angle distribution in momentum space. Hydrodynamic and nuclear transport models indicate that $v_{1}$ in the midrapidity region is sensitive to expanding participant matter during the early collision stages. Spectator nucleons influence the directed flow of identified hadrons, especially when the nuclear passage time is not short compared to the medium expansion time, which is also related to the radii of the colliding nuclei. Thus, studying the system size dependence of $v_{1}$ can provide insights into the QGP properties. This talk will present rapidity-odd directed flow ($v_{1}$) in various collision systems (O+O, Cu+Cu, Ru+Ru, Zr+Zr, Au+Au, U+U) at $\sqrt{s_{NN}} =$ 200 GeV using the AMPT model. We will discuss the slope of directed flow ($dv_{1}/dy$) across different systems.
A non-zero $\Delta v_{1}$ at non-zero $\Delta q$ has been proposed as a violation of the coalescence sum rule and attributed to electromagnetic fields, especially if $\Delta v_{1}$increases with $\Delta q$. Our recent study suggests a coalescence sum rule for the $v_1$ difference ($\Delta v_{1}$) among seven hadron species ($K^{-}$, $\phi, \overline{p}$, $\overline{\Lambda}$, $\overline{\Xi}^{+}$, $\Omega^{-}$ and $\overline{\Omega}^{+}$). We found that $\Delta v_{1}$ depends linearly on both the electric charge difference, $\Delta q$ and strangeness difference, $\Delta S$. This talk will also discuss the results of the coalescence sum rule in the beam energy range of $\sqrt{s_{NN}} =$ 7.7-200 GeV using the AMPT model.
Speaker: Dr Kishora Nayak (Department of Physics, Panchayat College, SU, Bargarh 768028, India) -
3:29 PM
Exploring transverse momentum fluctuations via study of $v_{0} (p_{T})$ in the AMPT and PYTHIA model 7m
Transverse momentum fluctuations serve as a powerful tool for probing the properties and evolution dynamics of the system formed in high energy heavy-ion collisions. Momentum fluctuations are sensitive to the equation of state as well as to the bulk-viscosity of the QCD system. An observable known as $v_{0}(p_{T})$ which quantifies the momentum fluctuations has been suggested to measure in experiments as it is strongly correlated with the fluctuations in the entropy per area, thereby providing a new handle on one of the most important initial state parameters. Hydrodynamic simulations with the hybrid models predict that $v_{0}(p_{T})$ shows a discernible mass hierarchy for pions, kaons, and protons. Recent studies also suggest that measurement of $v_{0}(p_{T})$ could serve as a valuable tool for refining our understanding of the bulk viscosity of the system and the speed of the sound in the medium formed in heavy-ion collisions.
In this work, we study the observable $v_{0}(p_{T})$ in p+p and Au+Au collisions at centre-of-mass energy 200 GeV using the PYTHIA8 and AMPT model, respectively. This study is performed in the kinematic acceptance range of $p_{T}$ from 0.2 to 5 GeV/c for inclusive charged hadrons and for identified particle species such as pion, kaon, and proton. The observable is calculated in a similar way as the harmonic flow $v_{2}(p_{T})$, using a gap in pseudo-rapidity to reduce non-flow effects. The effect of different hadronisation mechanisms in the models will be investigated. These model results would be useful for the future measurements in heavy-ion collision experiments.
Speaker: Debasish Mallick -
3:36 PM
Study of identified particle production as a function of transverse event activity classifier, $S_{T}$ in p$-$p collisions 7m
The underlying events (UE) in proton-proton (p$-$p) collisions encompass aspects of the interaction not attributed to the primary hard scattering, but arising from accompanying interactions of the rest of the proton.
Traditionally, UE studies involve defining topological regions relative to the leading particle in an event, with the transverse region being especially sensitive to UE activity. Various classifiers have been used to discriminate the extent of UE activity regions.This contribution introduces a new observable, $S_{T}$, defined as the sum of the transverse momentum of charged particles ($\sum_{i} p_{T_{i}}$ ) produced in p$-$p collisions at LHC energies to probe the underlying events. The production of identified particles like $\pi^{\pm}$, $K^{\pm}$, p , $K_{S}^{0}$, and $\Lambda^{0}$ are studied in different ranges of this transverse activity classifier in p$-$p collisions at $\sqrt{s} = 13 $ TeV using pQCD inspired PYTHIA 8 event generator. A comparative analysis of the identified particle spectra, mean multiplicity and mean transverse momentum has been carried out with respect to $S_{T}$ and the performance of this new observable is gauged by comparing the results with previously defined $R_{T}$ observable.
Speaker: Rahul Verma (IIT- Indian Institute of Technology (IN)) -
3:43 PM
Characterization of flavor dependance of Chiral Magnetic Effect with multiple correlators 7m
We study the flavor dependance of the Chiral Magnetic Effect (CME) using two of the primary correlators used to characterize the charge separation effect. These are the correlator $\Delta\gamma $ and the correlator $R_{{\psi}_2}$. We use the AMPT (A Multiphase Transport Model) model to study the sensitivity of these correlators to two and three flavors of quarks. The AMPT model used has a centrality dependent charge separation introduced in the initial stage. We find that both the correlators indicate a strong flavor dependence in $(30-50)\%$ centrality bins. We then create a classification model with a neural network architecture and train the model using numerous combinations of the final state particle distributions. We evaluate patterns of error distribution and determine which observables are best suited for precise and accurate CME flavor estimation. We additionally implement the model to estimate the $R_{{\psi}_2}$ correlator from the final state particle distribution and minimize the flow-related background effects. This method represents a novel approach to characterizing the CME flavors while reducing the background effect.
Speaker: Mr Somdeep Dey (School of Physics,University of Hyderabad) -
3:50 PM
Enhancing Signal Identification in Rare Higgs Boson Decay to Zγ and Complex Decay Processes at LHC Energies 7m
Higgs Boson is characterized by J$^\pi$ = 0$^+$ and fundamentally forms the cosmos by interacting with other particles to impart mass in standard model discovered in 2012 at CERN. This study is focused on Z$\gamma$ channel of Higgs with branching ratio of $\beta(H \rightarrow Z\gamma) = (1.57 \pm 0.09) \times 10^{-3}$. Feynman diagram for Z$\gamma$ channel is similar to $\gamma$$\gamma$ channel and loop diagrams in this process are particularly sensitive to BSM physics. Recent studies have measured $\kappa_{Z\gamma} = 1.65^{+0.34}_{-0.37}$ indicating a uncertainty 40\% . Deviation in standard model prediction $\kappa_{Z\gamma}=1$ can affect the decay rate $H \rightarrow Z\gamma$ and the Higgs production cross-section indicating the need for thorough research into $Z\gamma$. We have used PYTHIA8 Monte Carlo (MC) event generator for the analysis of $H\rightarrow Z\gamma\rightarrow \mu^+\mu^-\gamma$ or $e^+ e^-\gamma$ in proton-proton collisions at centre-of-mass energy $\sqrt{s}$ = 13 TeV. This research further explores a novel method to address challenges such as complex background noise and pile-up in dense media, as well as the detection of heavy resonance signals within the domain of heavy-ion physics. By employing an angular correlation technique, the study aims to enhance the Higgs signal-to-background ratio in both heavy-ion and proton-proton experiments. Higgs mass is reconstructed by employing selection criteria focused on certain kinematic variables at various stages and signal-to-background ratio computed. Further analysis involves examining relation between $P_{Z}$ vs $\theta_{\ell^+\ell^-}$ and $P_{H}$ vs $\theta_{Z\gamma}$ - refers to $1^{st}$ and $2^{nd}$ angular correlation respectively both were applied up to 1$\sigma$, which significantly increased the signal-to-background ratio by several orders of magnitude. Utilizing this approach in conjunction with several kinematic cuts is expected to improve signal detection in complex data sets. Furthermore, this study has also taken into the acceptance and efficiency to incorporate these factors into the cross-section calculation.
Speaker: Ms Manisha Kumari (Indian Institute of Technology Mandi)
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2:10 PM
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4:15 PM
Parallel C: QCD Phase Diagram. Chair: Rajarshi Ray
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2:10 PM
Transport properties of hot hadronic matter in heavy ion collisions. 18m
We estimate the transport coefficients like shear and bulk viscosities of hot hadronic matter in van der Walls hadron resonance gas ( VDW HRG ) model in the relaxation time approximation. We also have compared these results with excluded volume hadron resonance ( EV HRG ) calculations. η/s decreases as the temperature of the hadronic system increases at a fixed baryon chemical potential. η/s in VDW HRG is always less than that of EV HRG case due to the large entropy density in VDW HRG compared to EV HRG case. At a fixed chemical potential, ζ/s in VDW HRG is also less than that of EV HRG case. We also have estimated these transport coefficients along the freezeout curve. There is an increase in chemical freezeout temperature in VDW HRG case determined from the universal condition E/N=ϵ/n∼1 GeV. We also have calculated the variation of attraction parameter along the freezeout curve E/N=ϵ/n∼1 GeV keeping the freezeout parameters same as in ideal HRG and the repulsion parameter fixed. We observe a nontrivial variation of attraction parameter along the freezeout curve where it increases in the meson dominated region and decreases in the baryon dominated region along the chemical freezeout curve. η/s in EV HRG is always large than that VDW HRG along the freezeout curve. This is also true for ζ/s.
Speaker: Ranjita Mohapatra -
2:28 PM
Hybrid Regression and Explainable AI for Phase Transition Analysis of two flavour Quark Matter 13m
We investigate a hybrid approach of parametric and nonparametric
regression techniques to analyse the phase boundary between the
confined and deconfined phases of two-flavour quark matter. Data
derived from the Nambu-Jona-Lasinio (NJL) and Polyakov-loop extended
NJL (PNJL) models are trained and further used for the prediction of phase
transition boundaries with enhanced accuracy. We also observe the
classification of the order of phase transition and interpret the
model's predictions with extreme gradient boosting and SHapley Additive
exPlanations(SHAP) values. Our findings demonstrate that this learning
method effectively captures the complex behaviour of quark matter
transitions and is also useful to balance interpretability and
flexibility.Speaker: Tamal Kumar Mukherjee (Adamas University) -
2:41 PM
Studying the onset of Dimensional Reduction in finite temperature QCD and its consequences 13m
One of the outstanding challenges in the theory of strong interactions described by Quantum Chromodynamics is to understand its non-perturbative properties which can explain many important phenomena e.g., color confinement. In this work we study the non-perturbative sector of magnetic gluons whose momenta are given by $|\vec{p}|\leq g^2T/\pi$
in a finite temperature ($T$) QCD plasma described by strong coupling strength $g$, both in presence of 2+1 flavors of dynamical quark flavors and without. By performing lattice computations of the spatial Wilson line correlators for a wide range of temperatures from $160$-$1000$ MeV on different lattice spacings corresponding to $N_\tau=8, 12, 16$ for pure SU(3) gauge theory and $N_\tau=8, 10$ for 2+1 flavor QCD we extract the spatial string tension. From the temperature dependence of the spatial string tension we show that QCD can be described by a dimensionally reduced effective theory, EQCD at temperatures beyond $600$ MeV. We further extract the pseudo-potential whose long distance part is characterised by the spatial string tension and the short distance perturbative part described within perturbative EQCD. We demonstrate how this potential can explain the deviation of the screening masses of pseudo-scalar and vector meson-like long-distance
excitations of the QCD plasma from the perturbative estimates at high temperatures and provide an explanation for the significant difference between these screening masses that cannot be explained within perturbative QCD.Speaker: Swagatam Tah (The Institute of Mathematical Sciences) -
2:54 PM
Precision measurement of (Net-)proton Number Fluctuations in Au+Au Collisions from BES-II Program at RHIC-STAR 13m
Higher-order cumulants of (net-)proton multiplicity distributions are sensitive observables for studying the QCD phase structure. At low baryon chemical potential ($\mu_B$), lattice QCD calculations establish the quark-hadron transition to be a crossover, while at large $\mu_B$, QCD-based models predict a first-order phase transition that ends at a critical point.
Here, we focus on the search for the possible existence of the QCD critical point. We report precision measurements of cumulants ($C_n$) and factorial cumulants ($\kappa_n$) of (net-)proton multiplicity distribution upto fourth order in Au+Au collisions with $\sqrt{s_{NN}}$ =7.7 - 27 GeV measured by the STAR experiment from second phase of Beam Energy Scan program (BES-II) at RHIC. Using the high statistics data collected with upgraded detectors, we select protons and antiprotons at mid-rapidity $|y|<0.5$ within 0.4 $< p_{T} (GeV/$c$) < 2.0$. The dependence of measured cumulants and factorial cumulants on the collision energy and centrality will be presented. The measured data will be compared with calculations from lattice QCD, and expectations from various non-critical point models, such as the transport model UrQMD and the thermal model HRG.
Speaker: Bappaditya Mondal -
3:07 PM
Proton Intermittency analysis in Au + Au Collisions: Exploring Critical Behavior in the FAIR Energy Range 7m
In this presentation, we extend our previous investigations on intermittency using the Scaled Factorial Moment (SFM) technique in Au + Au collisions within the FAIR energy range of 2–12A GeV. Building on our findings published in Eur.Phys.J.A 59 (2023) 4, 92, we now focus on the fluctuations in the number of protons, motivated by QCD-inspired predictions that suggest critical behavior associated with net baryon density fluctuations. Employing a hybrid version of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) event generator, we analyze the intermittency across pseudorapidity χ(η) and azimuthal χ(ϕ) spaces. Utilizing three equations of state (EoS)—pure Hadron Gas (HG), Chiral + HG, and Bag Model EoS—we explore the distinct intermittent emission patterns and their dependence on incident beam energy. Our findings reveal distinct intermittent behaviors dependent on the chosen EoS, with the Bag Model EoS exhibiting stronger intermittency compared to Chiral+HG. Furthermore, we observe that the strength of intermittency decreases with increasing beam energy. These results highlight the significance of investigating proton fluctuations as a key approach to understanding the critical dynamics of QCD phase transitions and provide insights into the evolution of matter in high-energy collisions.
Speaker: Dr Anjali Sharma -
3:14 PM
Production of light nuclei in Au+Au collisions from STAR BES-II 13m
Light (anti-)nuclei production in heavy-ion collisions can be described by two different mechanisms: the thermal and coalescence models. By analyzing the yields and ratios of the light (anti-)nuclei, we can gain valuable insights into their formation processes and the properties of the system at freeze-out. The enhancement in the compound ratios of light nuclei, such as $N_{t}N_{p}/N_{d}^{2}$ from the expected coalescence baseline, has been proposed as a tool to probe critical phenomena in the Quantum Chromodynamics phase diagram. In the first phase of the RHIC Beam Energy Scan (BES-I), a notable increase in the compound light nuclei yield ratio $N_{t}N_{p}/N_{d}^{2}$ was observed in the most central Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV, with a combined significance of 4.1$\sigma$. The larger datasets ($\sim10\times$ BES-I) collected by the STAR during the second phase of the BES program (BES-II) and improved detector capabilities are expected to provide more precise measurements.
In this talk, we will explore the centrality and energy dependence of the transverse momentum ($p_T$) spectra of $p$, $\bar p$, $d$, $\bar d$, and $^{3}He$ in Au+Au collisions across BES-II energies $\sqrt{s_{NN}}$ = 7.7 - 27 GeV. Additionally, we will report the centrality and energy dependence of the $p_{T}$ integrated yields ($dN/dy$) and the mean $p_{T}$ ($\langle p_{T} \rangle$) of light nuclei. Furthermore, we will discuss the centrality and $p_T$ dependence of the coalescence parameters, $B_{A}$, with their broader physics implications.
Speaker: Sibaram Behera (IISER Tirupati) -
3:27 PM
Pionic and thermodynamic properties of hot QCD with two flavours from an effective field theory approach 13m
We construct an Euclidean effective field theory (EFT) for thermal Quantum Chromodynamics (QCD) with $N_f=2$ for physics near crossover temperature using the global symmetries of QCD. A cut-off scale is used along with the ${\rm \overline{MS}}$ regularization scheme and all dimension six operators including current-current interactions and a gradient cubed term are utilized. The gradient cubed term contributes to the free energy in the mean field theory (MFT) and modifies the gap equation, as a result of which its coefficient is constrained. Pion fluctuations around the MFT is treated to one-loop in fermions and used to match the theory to lattice computations. Matching the EFT at two temperature allows prediction of the temperature dependence of pion properties and thermodynamic quantities near the cross over.
Speaker: Pritam Sen (Tata Institute of Fundamental Research, Mumbai, India) -
3:40 PM
System size, energy and event shape dependence of the mean transverse momentum fluctuations with ALICE at the LHC 13m
Measurement of the event-by-event fluctuations of the mean transverse momentum, $\langle p_{\rm T} \rangle $, help to characterize the properties of the bulk of the system created in ultrarelativistic heavy-ion collisions, called the quark-gluon plasma (QGP). The fluctuations are closely related to the dynamics of the phase transition from the QGP to a hadron gas.
In this presentation, the $\langle p_{\rm T} \rangle $ fluctuations of charged particles produced in pp, Xe-Xe and Pb-Pb collisions at the LHC will be presented. The fluctuations are measured via the integral correlator, $\langle\langle \Delta p_{\rm T}\Delta p_{\rm T}\rangle\rangle $. The strength of the correlator is found to decrease monotonically with increasing charged-particle multiplicity measured at mid-rapidity in all three systems. In Xe-Xe and Pb-Pb collisions, the multiplicity dependence of the correlator is found to deviate significantly from a simple power-law scaling and from the predictions of the HIJING and AMPT models. The observed deviation is expected to arrise from the transverse radial flow in semicentral to central heavy-ion collisions. The correlation strength is also studied in pp collisions by classifying the events based on their event shape, transverse spherocity. Jetty events feature a larger correlation strength than isotropic events. The strength and multiplicity dependence of jetty and isotropic events are compared with calculations from PYTHIA 8 and EPOS LHC models.
Speaker: Tulika Tripathy (Université Clermont Auvergne (FR)) -
3:53 PM
Energy Evolution of QGP under two loop correction at finite chemical potential 7m
We calculate the energy evolution of quark gluon plasma (QGP) under the two loop correction
at finite chemical potential. The calculation shows a good improvement over the energy evolution
without chemical potential and the stability formation is also obtained at the size of 1.8 fm. This
indicates that QGP droplet can be found with changing the quark and gluon flow parameters.
However there is a lot of change in the stability of QGP droplet depending on the parameters contained in the systemSpeaker: Shougaijam Somorendro Singh (University of Delhi, Delhi, India) -
4:00 PM
Exploring Event-by-Event $p_{\rm T}$ Fluctuations in pp Collisions at $\sqrt{s} = 13$ TeV: An Insights from ALICE 13m
Event-by-event fluctuations of the mean transverse momentum ($p_{\rm T}$) of relativistic charged particles are analyzed using the two-particle correlator, $\sqrt{C_m}/M(p_{\rm T})_m$ which quantifies the correlations strength in units of the mean $p_{\rm T}$ in proton-proton collision at $\sqrt{s} = 13$ TeV in ALICE both for Minimum Bias and and High-multiplicity triggered events. The non-monotonic variations in $p_{\rm T}$ correlations with changing energy could serve as a signature of QGP formation. A comprehensive investigation across soft, intermediate, and hard $p_{\rm T}$ regions could provide crucial insights into both equilibrium (e.g., thermal radial flow) and non-equilibrium (e.g., jet/minijet) contributions to $p_{\rm T}$ fluctuations. The dependence of the correlator on particle multiplicity for different $p_{\rm T}$ window widths and positions is explored. The correlator values are found to decrease with increasing charged particle density, following a power-law behavior similar to observations in both small and large systems at lower energies. Additionally, the influence of $p_{\rm T}$ range on the power-law coefficient is studied and results are compared with predictions from Monte Carlo models, such as PYTHIA (pQCD string model) and EPOS (core-corona model), to enhance understanding of the underlying mechanisms driving $p_{\rm T}$ fluctuations.
Speaker: Tapan Nayak (CERN, Geneva and University of Houston)
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2:10 PM
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2:10 PM
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4:15 PM
Parallel D: Hard probes, heavy flavor. Chair: Vinod Chandra
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2:10 PM
Transport model calculations of jet energy loss and jet shape modifications 18m
We have developed a consistent model that combines parton jet shower production from perturbative QCD and the complicated interactions between the full jet with the medium soft partons in a MultiPhase Transport (AMPT) model. In addition to the elastic binary collisions existing in the model, we have incorporated the crucial energy-momentum modifications of the parton showers via medium-induced multiple gluon radiation in the higher-twist formalism of jet energy loss. Given the remarkable success of AMPT in addressing the anisotropic bulk medium flow, and noting the importance of jet modifications on the space-time dynamics of medium, the unified jet-medium parton transport framework can be used to make realistic predictions of the jet based observables. We have compared the numerical results of the model with the experimental data in central Pb-Pb collisions at the LHC energy of 5.02 TeV, to ascertain the impact of the medium and in particular the medium-induced radiation effects, on the jet energy loss, dijet asymmetry, and modifications of the full jet shapes.
Speaker: Prof. Subrata Pal (Tata Institute, Mumbai) -
2:28 PM
Lattice study of correlators for quarkonium decay 18m
Quarkonia are among the most studied probe of the quark-gluon plasma
created in relativistic heavy ion collisions. But a nonperturbative
theoretical formalism for quarkonia in plasma is difficult, and one
relies on an effective field theory formalism coupled with
lattice studies. If the system size is much less than the inverse
temperature, as is expected for bottomonia, the interaction of the
system with the medium can be approximated by a color electric field,
and the decay of the quarkonia can be studied as a transition
to an octet state through the interaction with the medium.
In an open quantum system framework,
such interactions are encapsulated in transport coefficients.We will present results of a lattice study of the correlators relevant
for this process, at temperatures in the range 1-2 times the deconfinement
temperature, for a gluonic plasma. We will also discuss the difference
between this transport coefficient and the one used for the diffusion of
a heavy quark in the plasma.Speaker: Saumen Datta -
2:46 PM
Collective flow measurement of $D_\mathrm{s}^{\pm}$ meson in PbPb collision at 5.02 TeV with CMS experiment 13m
The interaction of heavy quarks with the quark-gluon plasma (QGP) significantly influences their azimuthal distribution and transverse momentum ($p_{\mathrm{T}}$) spectrum, making azimuthal anisotropy coefficients ($v_n$) and nuclear modification factors ($R_{AA}$) essential tools for studying QGP properties, as they reveal collective flow and energy loss mechanisms of heavy quarks. In this talk, we present the first measurements of the elliptic ($v_2$) and triangular ($v_3$) flow coefficients of $D_{s}^{\pm}$ mesons in lead-lead (PbPb) collisions at a center-of-mass energy of 5.02 TeV, using the CMS experiment. The measurements, performed as a function of transverse momentum across various centrality classes, set a new standard of precision at this energy, expanding the kinematic range compared to previous studies. The broader kinematic coverage and the first-ever $v_3$ measurement of $D_{s}^{\pm}$ mesons provide new insights into charm quark flow generation mechanisms and the impact of hadronization on flow. We compare the flow of $D_{s}^{\pm}$ mesons with that of $D^{0}$ mesons to investigate the potential effect of strange quark hadronization. These results also offer a unique opportunity to explore the influence of initial-state effects on heavy quark dynamics. Additionally, comparison with theoretical models provides critical validation of the underlying physics mechanisms governing these processes.
Speaker: Nihar Ranjan Saha (Indian Institute of Technology Madras (IN)) -
2:59 PM
Thermodynamics of heavy Quarkonia using the SUSYQM method in the presence of baryonic chemical potential 7m
In this study, we employ medium-modified Cornell (MMC) potential to investigate the thermodynamic properties of ground states of heavy quarkonium systems in N-dimensional space through the Supersymmetric Quantum Mechanics (SUSYQM) approach. To account for the effects of baryonic chemical potential on quarkonia, we incorporate the quasi-particle Debye mass. The Schrödinger equation is solved to obtain the energy eigenvalues of the system. Using the derived partition function, we calculate essential thermodynamic properties such as internal energy, entropy, and free energy, examining their behavior under varying temperature and dimensionality number.
Speaker: Rishabh sharma (Department of Physics, Central University of Jharkhand, Ranchi, India- 835-222) -
3:06 PM
Non-perturbative Heavy Quark diffusion in the non-eikonal domain of the gluon bremsstrahlung 13m
Drag and diffusion coefficients of the Heavy Quarks (HQs), such as charm and bottom, are one of the prime tools for discerning the properties of the deconfined QCD medium created in the heavy ion collisions experiments. The innate non-perturbative nature of the QCD medium renders it imperative to estimate the transport coefficients in that domain. The present work evaluates the drag and diffusion coefficients of the moving HQ interacting with the medium particles via two-body collisional and three-body radiative processes to the first order in opacity by employing Gribov mechanism for the non-perturbative regime. We proffer the latest results of the HQ transport coefficients computed for the non-perturbative and non-eikonal gluon radiation off the HQ. We emphasize particularly on the importance of the non-eikonality in the non-perturbative domain. The calculations show significant increment of the transport coefficients with the increasing non-eikonality by juxtaposing the results with those of the perturbative and eikonal regions. We hope to shed fresh light towards explaining the experimental data on the nuclear modification factor, $R_{AA}$, the elliptic flow, $v_2$ of the HQ by advocating the importance of the non-eikonality of the gluon radiation off the HQ.
Speaker: Surasree Mazumder (Indian Institute of Science Education and Research, Berhampur) -
3:19 PM
Quarkonia Spectral Function at Finite Momenta 13m
Heavy quark-antiquark bound states such as $c\bar{c}$ and $b\bar{b}$, serve as essential tools for probing the properties of quark-gluon plasma (QGP). However, its finite momentum behaviour remains largely unexplored, despite its experimental significance. Here, we present an extension of quarkonia dynamics from zero-momentum to finite-momentum by observing its spectral function. We obtained the spectral function in threshold region by solving the Schrödinger equation with finite-momentum perturbative potential. We will model this spectral function with perturbative vacuum part to describe the lattice correlators at temperatures of 1.20 $T_c$, 1.40 $T_c$, and 1.62 $T_c$ in 2+1 flavor QCD.
Speaker: Pavan Pavan -
3:32 PM
Effects of memory on quarkonium evolution in quark gluon plasma 13m
Heavy-Quarkonia evolution in quark-gluon plasma (QGP) can be studied using the framework of open quantum systems. The density matrix of the quarkonia satisfies a simple Lindblad-type equation if one assumes that the binding energy $E_b$ is much smaller than the medium temperature $T$. This approximation does not hold for a significant part of the QGP evolution. We study the evolution of quarkonia in the regime when $E_b \sim T$ by solving general master equations for the density matrix, which include the effects of memory. Mainly we calculate suppression of $\Upsilon(1S)$ at CMS and RHIC energies. For the background medium, we use results from a realistic viscous 2+1 hydrodynamic simulation, which gives a good description of the phenomenology of the soft particles.
Speaker: Vyshakh B R (Tata Institute of Fundamental Research, Mumbai) -
3:45 PM
A model study for the understanding of particle production through jet-hadron correlation in pp collisions at 13 TeV 7m
At large hadron collider energies, a remarkable similarity has been observed in particle production mechanisms between large and small collision systems. In particular, the enhancement in baryon-over-meson ratios at intermediate transverse momentum and/or relative enhancement in production of particles with higher strangeness content at large multiplicities indicates that it may be possible that a partonic medium is also produced in the collisions of small systems. To classify broadly, particles are either produced via some non-perturbative QCD processes that involve quark-hadron duality or from hard QCD processes like jet-fragmentation which are theoretically better constrained. To understand the anomalous particle production in small systems it is important to separate the particles produced in hard processes (jets) from those produced in the soft underlying events. This would provide a better understanding of the similarities and differences in the particles production mechanism from small to large collision systems.
In this work we use jet-hadron correlation technique to separate particles which are produced in association with a hard process or jet from the underlying events in MPI-enabled PYTHIA8. This model has reasonable success in describing some features of the data in small systems which are generally linked with the medium formation. We calculate baryon-over-meson ratios of the particles in jets and in underlying events in minimum bias as well as high multiplicity events to understand whether the enhancement of baryon-over-meson ratios are linked with any modification of jet-fragmentations particularly in high multiplicity events or it comes from underlying events. We also compare our calculations with inclusive results and the available data.Speaker: Sanchari Thakur (Bose Institute (IN)) -
3:52 PM
Investigating Radius-Dependent Jet Quenching Dynamics with the JETSCAPE Framework 7m
In this work, we extend the JETSCAPE framework to investigate the dependence of the jet nuclear modification factor, ${R_{AA}}$, on the jet radius parameter ($R$) for larger jet cones with radii up to $R = 1.0$. The study primarily aims to explore high-${p_{T}}$ inclusive jets, reaching up to 1 TeV, to analyze quenching effects within the quark-gluon plasma created in the most-central (0-10\%) Pb-Pb collisions at ${\sqrt{\rm s_{NN}}} = 5.02$ TeV. To achieve this, we couple the MATTER module, which models the high-virtuality stage of parton evolution, with the LBT module for the low-virtuality phase, as well as with the AdS/CFT and MARTINI modules for enhanced precision across different interaction regimes. The MUSIC (2+1 )D model is employed to present the hydrodynamic evolution of the quark-gluon plasma in these Pb-Pb collisions. These calculations are then compared to experimental data collected from ATLAS and CMS detectors, with JETSCAPE predictions showing consistency across high-${p_{T}}$ values and large jet radii, within the deviations of 10-25\%. A major aspect of this work is computing the double ratio (${R^{\mathrm{R}}_{\mathrm{AA}}/R^{\mathrm{R=small}}_{\mathrm{AA}}}$), which helps to isolate the effect of jet radius on energy retention within the QGP, providing new insights into its dependence on jet-$R$ and jet-${p_{T}}$ and advancing our understanding of jet quenching dynamics in a strongly interacting QCD medium. The observed trends align well with JETSCAPE’s multi-stage hydrodynamic model of parton shower evolution.
Speaker: Ms Manaswini Priyadarshini (Tata Institute of Fundamental Research (IN)) -
3:59 PM
Effect of initial states on the production of heavy flavors using azimuthal angular correlation 7m
Heavy flavors (charm and beauty) are created via initial hard scatterings in ultra-relativistic heavy-ion collisions. The study of thermalization of heavy flavors in the Quark Gluon Plasma (QGP) is one of the major physics goals of the upcoming heavy-ion experimental programs. Azimuthal angular correlations ($\Delta\varphi$) of open heavy flavour species are expected to be influenced by the thermalization of heavy quarks. Besides thermalization, $\Delta\varphi$ distributions of heavy flavors also serve as an excellent tool to look into heavy flavor production processes. Furthermore, differential studies in $\Delta\varphi$ correlations will give ample information about heavy quark dynamics in the heavy-ion collision at different kinematic ranges.\
In this contribution, we present a transverse momentum ($p_{\mathrm{T}}$) differential study of the azimuthal angular correlations of $\rm{D^0-\bar{D}^{0}}$ and $\rm{B-\bar{B}}$ mesons in pp and Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.5 TeV using PYTHIA8. We also perform multiplicity differential calculations to examine the effects of the multi-parton interactions (MPIs) on the $\Delta\varphi$ distributions. Our findings suggest that MPI modifies the $\rm{D^0-\bar{D}^{0}}$ correlations significantly, especially at low $p_{\mathrm{T}}$, while a weak multiplicity-dependence is observed for $\rm{B-\bar{B}}$ correlations. In Pb--Pb collisions, azimuthal angular correlations of $\rm{D^0-\bar{D^0}}$ are important from the perspective of charm thermalization while checking for additional initial state effects. We quantify the effect of nuclear parton distribution functions (PDF) on $\rm{D^0-\bar{D}^{0}}$ and $\rm{B-\bar{B}}$ correlations by measuring the yield and width of the respective $\Delta \phi$ distributions. The correlation distribution also show sensitivity to the parton level processes, gluon splitting show its imprints in the NS peak of correlation distribution in the form of double NS peak at low trigger $p_{\mathrm{T}}$ observed for both charm as well as beauty quark. This study is crucial for drawing robust conclusions about the thermalization of heavy quarks in the QGP.
Speaker: Swapnesh Khade (Indian Institute of Technology Indore (IN))
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2:10 PM
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4:18 PM
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4:35 PM
Coffee / Tea Break
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4:35 PM
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6:00 PM
Parallel A: Resonances, strange hadrons, hard probes. Chair: Chitrasen Jena
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4:35 PM
Understanding the hadronic phase with resonance studies with ALICE at LHC Energies 13m
Hadronic resonances, with lifetimes comparable to the duration of the hadronic phase, can be used as effective probes for studying its evolution in heavy-ion collisions. Exploring the dynamics of the hadronic phase reveals the roles of rescattering and regeneration in resonance production. In particular, rescattering reduces the resonance yields and may alter their transverse momentum, while regeneration can lead to their enhancement. By analyzing the ratios of resonance yields to those of long-lived particles across various charged-particle multiplicities, valuable insights into hadronic interactions and system evolution are obtained. Additionally, comparing results from smaller collision systems, such as pp and p--Pb, with larger systems like Xe--Xe and Pb--Pb collisions highlights potential collective phenomena and variations in the lifetime of the hadronic phase.
This contribution presents ALICE results from Run 2 and Run 3 on mesonic and baryonic resonances across various collision systems at LHC energies. Focus on the $\rm K^{*0}(892)$, $\Lambda(1520)$, $\Sigma^{\pm}(1385)$, $\Xi^{0}(1530)$, and $\phi(1020)$ resonances will be given, in particular on their transverse momentum ($p_{\rm T}$) distributions, their $p_{\rm T}$-integrated yields, and the ratios of $p_{\rm T}$-integrated resonance yields to those of long-lived particles. Furthermore, the experimental results will be compared with theoretical predictions to understand the particle dynamics in the hadronic phase.
Speaker: Sonali Padhan (IIT- Indian Institute of Technology (IN)) -
4:48 PM
Probing hadronic rescattering via $K^{*0}$ resonance production at RHIC 7m
Relativistic heavy-ion collisions provide a unique setting to investigate QCD matter under varied temperatures and densities. As the collision energy rises, the baryon chemical potential ($\mu_{B}$) decreases, resulting in a mid-rapidity region rich in baryons at the lower Beam Energy Scan (BES) program energies and in mesons at top RHIC energies. Short-lived resonances like $K^{*0}$ (lifetime $\sim$ 4.16 fm/$c$) are effective probes of the hadronic medium. As they primarily decay within the fireball, their decay products undergo in-medium effects like rescattering and regeneration, potentially modifying $K^{*0}$ properties. However, due to change in the chemical composition of the system produced at low and high collision energies, distinct difference in the particle interaction can be expected. The measurement of $K^{*0}$ meson over a broad collision energy range will help shed light on this phenomenon.
In this presentation, we will report precision measurements of $K^{*0}$ mesons in isobar (Zr+Zr and Ru+Ru) collisions at $\sqrt{s_{NN}}$ = 200 GeV and in Au+Au collisions at $\sqrt{s_{NN}}$ =7.7,11.5,14.6,19.6, and 27 GeV, using high-statistics STAR BES-II data. Results will include transverse momentum ($p_{T}$) spectra, yields ($dN/dy$), and mean transverse momentum ($\langle p_{T}\rangle$). Additionally, the $K^{*0}/K$ ratio as a function of multiplicity across different systems and energies will be discussed, providing insights into the underlying physics of the hadronic medium.
Speaker: Mr Aswini Kumar Sahoo (Indian Institute of Science Education and Research, Berhampur) -
4:55 PM
Study of resonances flow and production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.36 TeV with ALICE 13m
Hadronic resonances play an important role in understanding the different phases of the evolution of relativistic heavy-ion collisions. Due to the short lifetime of resonances, their yields may be influenced by interactions in the final stage hadronic phase where rescattering can alter the momentum of the resonance decay products, preventing their reconstruction through invariant-mass analysis, while pseudo-elastic hadron scattering can regenerate them. ALICE measurements have shown evidence of the rescattering effect through the measurements of resonance yields and comparing them with stable hadrons. Another key observable that provides insight into final-state effects is the measurement of elliptic flow ($v_{2}$), which results from the system's anisotropic expansion due to the initial spatial asymmetry in the collision geometry. Late-stage hadronic rescattering can alter the momentum distributions of resonances, thereby influencing their elliptic flow. Therefore, measuring the elliptic flow of resonances like $K^{*0}$ and $\phi$ along with their yields can provide deeper insights into the impact of rescattering effects.
In this contribution, we present the latest ALICE results from Run 3, focusing on the measurement of elliptic flow and the production of $K^{*0}$ and $\phi$ resonances in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.36 TeV. The measurements will be compared with the ALICE results from Run 2 data.
Speaker: Sarjeeta Gami (National Institute of Science Education and Research (NISER) (IN)) -
5:08 PM
Study of exotic resonances in pp collisions with ALICE at LHC 13m
Quantum Chromodynamics (QCD) is a fundamental theory on which the Standard Model of particle physics is based, describing strong interactions between quarks and gluons. While conventional hadrons are composed of bound states of quark-antiquark ($q\bar{q}$) pairs or three-(anti)quark (qqq or $\bar{q}\bar{q}\bar{q}$) combinations, QCD also predicts exotic hadrons, such as $\mathrm{f_0(980)}$ and $\mathrm{f_1(1285)}$, which could be a tetraquark state or molecular state of mesons. Additionally, QCD predicts the existence of glueballs, which are bound states of gluons whose internal structure remains unknown, offering unique insights into the non-perturbative regime of QCD. The large statistics data collected by the ALICE detector in Run~2 in the pp collisions at $\sqrt{s} = 13$ TeV is used to perform detailed studies of exotic resonances.
This contribution reports on the measurements of production yields, mass spectra, and decay channels of the resonances $\mathrm{f_0(980)}$ and $\mathrm{f_1(1285)}$. Based on the lattice QCD prediction of the lightest scalar glueball candidate in the mass range of 1500 to 1700 MeV/c$^2$, we will also show the measurements of higher mass resonances at midrapidity in the mass range of 1000–2000 MeV/c$^2$ through $\mathrm{K_S^0K_S^0}$ and $\mathrm{K^+K^-}$ decay channels, aiming to explore their internal structure, production mechanisms, and alignment with QCD predictions.
Speaker: Mr Sawan Sawan (National Institute of Science Education and Research (NISER) (IN)) -
5:21 PM
Data driven analysis of jet energy loss distribution in relativistic heavy ion collision 7m
We present a numerical investigation of partonic energy loss in the Quark-Gluon Plasma (QGP) using a data-driven Bayesian inference framework. This study explores the energy, transverse momentum, and angular characteristics of the energy loss distribution associated with medium-induced multiple gluon emissions by hard partons traversing the QGP. The inference process employs the Markov Chain Monte Carlo method, implemented via the Metropolis-Hastings algorithm. Independent radiation mechanisms are modeled under the effects of boost-invariant longitudinal expansion, incorporating gamma and log-normal energy distribution functions to examine transverse momentum broadening and angular profiles of partonic cascades, providing insights into the interplay between medium properties and partonic evolution. Our results demonstrate con-
sistent nuclear modification factor RAA values with the LHC data across both energy distributions.Speaker: Riddhiman Roy (Indian Institute of Technology, Hyderabad) -
5:28 PM
Study of charm fragmentation using charm-hadron angular correlation measurements with ALICE 7m
In recent years, measurements of charm baryon-to-meson yield ratios highlighted a modification of the hadronization process in proton–proton collisions with respect to e+e− collisions. This invalidated the assumption at the basis of several theoretical calculations based on a factorisation approach that the cross section of charm hadrons can be calculated by parametrising the transition from charm quarks to charm hadrons with fragmentation functions tuned on to e+e− data. Additionally, the measurement of charm-hadron-tagged jets and correlations provides direct insights into initial parton kinematics, fragmentation processes, and hadronization mechanisms, underscoring their significant importance.
In this presentation, we introduce the latest ALICE results on angular correlations between heavy-flavour (HF) hadrons (triggers) with charged particles, and on jets containing HF particles. In particular, we report the results of angular correlations between strange and non-strange D-meson triggers with charged particles in pp collisions, including the first studies performed on Run 3 data. We also show the comparison between angular correlations obtained considering charm mesons and charm baryon (Λ+c) triggers in pp collisions. These measurements will give insights into the differences in the charm fragmentation between
charm baryons and mesons. We also present the final measurement of the longitudinal momentum fraction of jets carried by Λ+c baryons in pp collisions at √s = 13.6 TeV. This observable is particularly valuable as it provides a more direct link to the charm fragmentation functions and imposes more stringent constraints on hadronization mechanisms.Speaker: Ravindra Singh (Universita e INFN, Padova (IT))
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Parallel B: Collectivity. Chair: Prabhat Pujahari
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4:35 PM
Photons as a probe of the strongly interacting matter in heavy ion collisions 18m
Photons as a probe of the strongly interacting matter in heavy ion collisions
Speaker: Rupa Chatterjee -
4:53 PM
Baryon dynamics from recent measurements on directed flow and polarisation 18m
Baryon dynamics from recent measurements on directed flow and polarisation
Speaker: Subhash Singha -
5:11 PM
Phenomenology of baryon stopping and diffusion at RHIC BES 7m
A baryon-rich medium is created in low-energy heavy-ion collisions. Using a hydrodynamic model that incorporates finite baryon density, we investigate the role of baryon stopping and diffusion in RHIC-BES phenomenology, focusing on the directed flow ($v_1$) observable. The $v_1$ splitting between protons and anti-protons has been an elusive observable for a long time, primarily due to improper modeling of initial baryon stopping. We propose an initial baryon deposition model capable of reproducing the $v_1$ of protons and anti-protons across collision energies $\sqrt{s_{\mathrm{NN}}} = 7.7$–$200$ GeV. Notably, we find that the sign change of proton $v_1$ at $\sqrt{s_{\mathrm{NN}}} = 7.7$ GeV arises from a combined effect of initial baryon stopping and strong baryon diffusion—previously interpreted as a signature of a first-order phase transition. Using this baryon stopping model, we provide the first estimate of the baryon diffusion coefficient in the baryon-rich QGP medium.
Furthermore, leveraging our phenomenologically successful model, which accurately describes bulk observables at STAR BES energies, we explore the centrality-dependent splitting of the $v_1(y)$ slope, $\Delta(dv_1/dy)$, between positively and negatively charged hadrons. This splitting, recently measured by the STAR collaboration, has been suggested as a potential signature of the electromagnetic field generated during collisions. However, our calculations—accounting solely for baryon diffusion and not electromagnetic field effects—effectively reproduce the centrality trend of the $v_1$ slope splitting between protons and anti-protons. In this context, I will discuss how initial-stage baryon stopping provides a substantial background to electromagnetic field signals. Additionally, we demonstrate the significance of measuring rapidity-even $v_1$ splitting between baryons and anti-baryons, shedding light on the baryon junction conjecture, which has garnered considerable interest.Speaker: Mr Tribhuban Parida (IISER Berhampur) -
5:18 PM
Enhancing Bayesian parameter estimation by simultaneously adapting to multiple energy-scales with RHIC and LHC data 13m
The evolution of the strongly interacting medium formed in heavy-ion collison is modelled with multi-stage models. The models are driven by a large number of parameters that quantify the properties of the medium and the initial stage of the heavy-ion collision. The need to find model parameters which give the best description of the experimental data imposes a multidimensional optimization problem. The Bayesian analysis has shown to be successful in constraining the parameter values, and the combined inclusion of LHC Pb$-$Pb 5.02 and 2.76 TeV data with additional flow observables has greatly narrowed down the uncertainties [1].
In this talk, we present our latest study in inferring the transport properties of QGP by including the RHIC Au$-$Au collision data in addition to the LHC data used in the previous studies [1]. Additionally, we now define the centrality separately for all parametrisations instead of using a singular definition for all of them. With the added Au$-$Au data and exclusive centrality calibration, the data now favour smaller values for nucleon width and minimum distance between nucleons. The model calculations with the $\textit{maximum a posteriori}$ (MAP) parameters give notably better agreement with the data for the anisotropic flow and the identified particle yields than the previous results.
Furthermore, we quantify the sensitivities of newly developed flow observables, Asymmetric Cumulants and Symmetry Plane Correlations, highlighting the importance of measuring independent and sensitive observables. Finally, we explore alternative initial-state models with fewer parameters to improve the estimation and address the current model limitations. This is further studied by comparing the marginal likelihood of the models. These efforts require ongoing advancements in both theoretical frameworks and computational methods.
[1] J.E. Parkkila $\textit{et al.}$, New constraints for QCD matter from improved Bayesian parameter estimation in heavy-ion collisions at LHC, $\textit{Physics Lett. B 835}$, 137485
Speaker: Maxim Virta (University of Jyväskylä) -
5:31 PM
Hadron production at centre of mass energies 62.4, 200 and 2760 GeV , RHIC and LHC energies through recombination model 7m
We use the Recombination Model to explain the hadron production data at center of mass energies 62.4, 200 and 2760 GeV at LHC and RHIC. The Recombination model considers the effective valence quark energy and momentum without taking the sea quarks and gluons explicitly into account. This model has been quite successful in explaining the larger-than-expected baryon-to-meson ratio and the leading particle effect in heavy ion collision experiments. This model also provides a general framework to describe the whole momentum spectrum of the matter created in such experiments, without any restriction to the high or low transverse momenta regime for $p_T$<20 GeV/c. In this model, the hadron yield is a convolution of the probability of finding the valence quarks with the specific momenta and the probability of recombination of the quarks to produce the hadron. The sources of the recombining quarks can be classified as either of thermal (having transverse momenta < 3 GeV/c) origin or of shower origin (having transverse momenta > 3 GeV/c). We propose the expressions for the probability of recombination of the quarks into produced hadrons with the help of energy-momentum conservation laws. We consider the effect of the confinement of valence quarks inside the hadrons explicitly. For low transverse momentum, we use a thermal distribution of the recombining quarks, and for high transverse momentum, we take the momentum distribution from the fragmentation functions obtained in previous works. Using this formalism, we were able to explain the meson production at low transverse momentum ($p_T$ < 3 GeV/c) satisfactorily for the first time. We also present an empirical formula for the dependence of the hadron yield on the center of mass energy and the number of participants in the collision. We were also able to reproduce the low and intermediate transverse momentum spectra (0 < $p_T$ < 8 GeV/c) of the hadrons satisfactorily.
Speaker: Somenath Pal -
5:38 PM
An investigation of forward-backward correlations in hybrid UrQMD-hydro generated data 7m
One of the prime objectives of heavy ion collisions (HIC) is to find experimental evidence of the deconfinement phase transition from hadronic matter to quark-gluon plasma (QGP) in the reaction products of heavy ion collisions. Various hadronic models are used to study the investigation of the signature of QGP. One of the most successful models is the hybrid UrQMD-hydro model. It is a micro+macro hybrid approach that incorporates a hydrodynamic phase into the UrQMD hadronic model using Equations of State (EoS's). The evolution of the system is divided into three parts: (i) initialize with particle degrees of freedom; (ii) evolve with hydrodynamics; and (iii) free particle production with the Cooper-Frye approach.\par
Numerous observables are used to study correlations and fluctuations in HIC. One such important observable is forward-backward (F-B) correlations in rapidity or pseudorapidity space. The source of the fluctuations in the final state phases is the initial event-by-event fluctuation in energy density. Many researchers have already studied F-B correlations. A rigorous study on F-B correlations in nucleus-nucleus collisions has been reported by NA22 Collaboration, STAR of RHIC, and ALICE of LHC. The same study will be significant to be carried out at the highest SIS100 energy of FAIR as according to the hydrodynamical calculations the deconfined phase boundary will be accessible around the same energy. In this study, an attempt has been made to investigate the F-B correlation in UrQMD-hydro generated data for 10 AGeV Au+Au collisions.Speaker: Somen Gope (Bose Institute) -
5:45 PM
Investigation of the cluster structures in light nuclei through photon flow in O+O collisions at LHC energies 7m
In relativistic nuclear collisions, spatial anisotropies characterized by initial eccentricity, triangularity, and higher-order eccentricities arise from the geometry of the collision and fluctuations in the initial energy density distribution. These spatial anisotropies subsequently manifest as momentum anisotropies in the final-state particles through the collective expansion of the hot and dense medium produced in such collisions. The presence of cluster structures in light nuclei, such as $^{7}$Be, $^9$Be, $^{12}$C, and $^{16}$O, induces nuclear deformities, resulting in significant spatial anisotropies in the overlap region when collided at relativistic energies.
A recent proposal for dedicated $^{16}$O-$^{16}$O collision runs at 7 TeV at the LHC has opened up the opportunity for experimental verification of cluster structures at such energies and investigation of $\alpha$-cluster structures in light nuclei by examining final state observables in relativistic nuclear collisions. Moreover, the system size of $^{16}$O-$^{16}$O collisions is comparable to high-multiplicity proton-proton (pp) and peripheral lead-lead (Pb-Pb) collisions which provides a unique opportunity to investigate the origins of collective behavior in small collision systems.
In this work, we investigate the initial state produced in collisions of $\alpha$-clustered oxygen nuclei at 7 TeV assuming tetrahedral structures. We use GLISSANDO initial conditions and study the resulting flow observables for photons within the framework of the MUSIC hydrodynamics model and state-of-the-art rate of photon production. Our study compares these results with those from unclustered $^{16}$O-$^{16}$O collisions, revealing significant qualitative and quantitative differences in photon observables between the two cases.
We demonstrate that photon observables in $^{16}$O-$^{16}$O collisions can serve as a valuable probe for investigating the nucleon-level geometry as well as the initial state produced in relativistic nuclear collisions.Speaker: Sanchari Thakur (Bose Institute (IN))
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Parallel D: Hard probes, heavy flavor. Chair: Santosh K Das
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4:35 PM
Recent developments in open heavy-flavour physics: ALICE highlights 18m
Recent advances in the field of open heavy-flavour physics have provided profound insights into the behavior of heavy quarks (charm and beauty) in extreme conditions of matter created in high-energy heavy-ion collisions. The ALICE experiment at the Large Hadron Collider (LHC) has been at the forefront of these studies, offering precision measurements and groundbreaking results that shed light on the properties of the quark-gluon plasma (QGP).
This mini-review talk will summarize recent ALICE highlights in open heavy-flavour physics, focusing on the production, propagation, and hadronization of heavy quarks in heavy-ion collisions. Key topics include the energy loss of heavy quarks in the QGP, constraints on the transport coefficients of the medium, and the interplay between heavy-flavour hadronization and the surrounding QGP. Results from proton-proton (pp) and proton-lead (p-Pb) collisions will also be discussed.
In addition, the presentation will offer a glimpse into upcoming challenges and opportunities in the field, highlighting planned upgrades to ALICE and prospects for future measurements. With the next phase of experiments on the horizon, the discussion will emphasize how these new findings will shape our understanding of heavy-flavour interactions and the properties of the QGP.
Speaker: Samrangy Sadhu (University of Bonn (DE)) -
4:53 PM
Heavy quarks in glasma 18m
Heavy quarks in glasma
Speaker: Pooja Pooja (University of Jyväskylä) -
5:11 PM
Can high-p⊥ theory and data constrain η/s? 18m
Understanding the temperature dependence of the viscosity-to-entropy ratio (η/s) is essential for characterizing the properties of the matter produced in ultra-relativistic heavy ion collisions at RHIC and LHC. Low-p⊥ theory and data are, however, weakly sensitive to the commonly assumed forms of the temperature dependence of η/s, especially at high temperatures. To address this, we use high-p⊥ data and theory to impose further constraints on it. Our approach, based on the study of dynamical radiative and collisional energy loss of jet particles in the medium, yields promising results in constraining the temperature dependence of η/s. This demonstrates the utility of combining low-p⊥ and high-p⊥ methods to better constrain the properties of the Quark-Gluon Plasma (QGP).
Speaker: Dr Bithika Karmakar (University of Wroclaw) -
5:29 PM
Study of Heavy Quark Momentum Broadening in a Non-Abelian Plasma in- and out-of-equilibrium 13m
Heavy quarks are formed in the earliest stages of heavy-ion collisions and hence carry comprehensive information about the entire evolution of the initial non-equilibrium glasma phase to a quark-gluon plasma phase, its subsequent hydrodynamic evolution and hadronization at later stages. One of the quantities of interest to model this evolution and to compare with experimental observations is the heavy quark momentum diffusion coefficient $\kappa$, which determines how strongly these interact with the medium. We first estimate $\kappa$ relevant for the pre-thermalization stage in a highly occupied state of SU(2) gauge fields inspired from the color glass condensate (CGC) effective theory. For this we implement for the the first time, relativistic evolution of heavy quarks in the mass range of charm and bottom quarks in a background of over populated SU(2) gauge fields which are evolved using classical-statistical real-time lattice techniques. Based on a novel methodology to extract the momentum broadening for relativistic quarks, in out-of-equilibrium conditions, we find that the momentum distribution of heavy quarks exhibit interesting non-perturbative features at initial times eventually going over to a diffusive regime, where we extract the momentum diffusion coefficient [1]. We find a sizeable discrepancy between the results, calculated earlier in the static limit. We further extend our techniques to estimate $\kappa$ for heavy quarks in SU(2) gauge theory at high temperatures where its magnetic modes can be described classically within an effective theory [2]. By combining these results we also can provide a comparative study of kinetic equilibration times for charm and bottom quarks relevant for heavy-ion experiments.
References:
[1] Harshit Pandey, Soeren Schlichting, and Sayantan Sharma. Heavy-Quark
Momentum Broadening in a Non-Abelian Plasma away from Thermal Equilibrium. Phys. Rev. Lett., 132(22):222301, 2024.
[2] Dietrich Bodeker. On the effective dynamics of soft non-Abelian gauge fields at finite temperature. Phys. Lett. B, 426:351–360, 1998.Speaker: Harshit Pandey (The Institute of Mathematical Sciences, Chennai, India) -
5:42 PM
Diffusion coefficients of D-meson in rotating Hadron gas 7m
In off-central heavy ion collisions (HIC), the initial orbital angular momentum (OAM) of the colliding heavy nuclei can be transferred to the participants and subsequently to the nuclear medium formed. This finite OAM can lead the system to rotate with some finite angular velocity. The transport properties, like electrical conductivity, viscosities, thermal conductivity, heavy meson diffusion, etc, of the rotating nuclear medium are generally modified with respect to their non-rotating counterparts. The diffusion coefficients of heavy mesons and the corresponding nuclear suppression factor RAA are useful probes to understand the nature of the medium formed in the HIC experiments. In this work, we have determined the anisotropic spatial diffusion coefficients of D-meson diffusing under the background of rotating hadronic gas. To calculate the diffusion coefficients, we have set up a covariant Boltzmann transport equation in the rotating frame using the relaxation time approximation. The background hadron gas has been modeled by the popular hadron resonance gas model (HRG). The relaxation time is determined by assuming a hard-sphere-type scattering model of the D-meson with the HRG. The range for the scattering length “a” of the D-meson-HRG interaction is obtained by varying “a” to cover the results of the existing model calculation of the parallel component of diffusion. After calibrating the scattering length, we obtain the variation of the perpendicular and hall diffusion coefficients both with respect to temperature and angular velocity.
Speaker: Mr Ashutosh Dwibedi (Indian Institute of Technology Bhilai (IIT Bhilai))
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IAC Meeting: Room: Parallel C
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Plenary
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9:00 AM
Imaging nuclei by smashing them: how can shapes be revealed despite violent collisions? 25m
Imaging nuclei by smashing them: how can shapes be revealed despite violent collisions?
Speaker: Jiangyong Jia (Stony Brook University (US)) -
9:25 AM
Baryon and strangeness number fluctuation at LHC energies 25m
Baryon and strangeness number fluctuation at LHC energies
Speaker: Sourav Kundu (CERN) -
9:50 AM
Non-equilibrium evolution of slow-mode correlation and spectral functions near the QCD critical point 25m
We investigate the non-equilibrium effects on the structure of the correlation and spectral functions of the slow modes as the collision system evolves through the vicinity of the QCD critical point, within the time-dependent Ginzburg-Landau approximation. We model the time-evolution equation for the slow modes, by allowing the coefficients to be time-dependent. Within this framework, we study a competition between the diverging fluctuation and critical slowing in the critical region.
Speaker: Hirotsugu Fujii -
10:15 AM
Forward Physics at LHC-ALICE 25m
Forward Physics at LHC-ALICE
Speaker: Tatsuya Chujo (University of Tsukuba (JP))
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Coffee / Tea Break
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Plenary
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11:00 AM
Spin polarization in heavy ion collisions and relativistic spin hydrodynamics 25m
Spin polarization in heavy ion collisions and relativistic spin hydrodynamics
Speaker: Amaresh Jaiswal (National Institute of Science Education and Research) -
11:25 AM
Polarization measurement in relativistic heavy ion collisions 25m
Polarization measurement in relativistic heavy ion collisions
Speaker: Zhenyu Chen (Shandong University (CN)) -
11:50 AM
Quantum kinetic theory and spin polarisation in relativistic heavy ion collisions 25m
Quantum kinetic theory and spin polarisation in relativistic heavy ion collisions
Speaker: Shi Pu -
12:15 PM
QCD-Gravity double-copy in the Regge regime via shockwave collisions 25m
We present new results for gravitational wave radiation in ultrarelativistic collisions of black holes which are described as Aichelburg-Sexl shockwaves. We demonstrate that the effective “Lipatov” vertex governing graviton radiation is a mathematical double copy of the corresponding effective gluon emission vertex in heavy-ion collisions [1]. We also show that propagators in the gravitational shockwave background are double copies of the corresponding propagators in the gluon shockwave background [2]. The existence of these double-copy relations suggest that CGC-based techniques that describe the energy evolution of gluon radiation in QCD can similarly be applied to study the gravitational wave radiation spectrum in close black hole encounters [4].
[1] H. Raj and R. Venugopalan, “Universal features of 2→N scattering in QCD and gravity from shockwave collisions,” Phys. Rev. D 109, no.4, 044064 (2024) [arXiv:2311.03463 [hep-th]].
[2] H. Raj and R. Venugopalan, “QCD-gravity double-copy in the Regge regime: Shock wave propagators,” Phys. Rev. D 110, no.5, 056010 (2024) [arXiv:2406.10483 [hep-th]].
[3] H. Raj and R. Venugopalan, “Gravitational wave double copy of radiation from gluon shockwave collisions,” Phys. Lett. B 853, 138669 (2024) [arXiv:2312.03507 [hep-th]].
[4] H. Raj, A. M. Stasto and R. Venugopalan, in progressSpeaker: Himanshu Raj (Stony Brook University) -
12:40 PM
Application of machine learning and quantum computation in high energy physics 25m
Application of machine learning and quantum computation in high energy
physics
Speaker: Shuzhe SHI (Tsinghua University)
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Lunch
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Closing Session
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Concluding remarks 25mSpeaker: Sourendu Gupta
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Next ATHIC 10mSpeaker: Nu Xu
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Presentation and Vote of thanks 30m
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