Overview
The on-line seminar series on “RHIC Beam Energy Scan: Theory and Experiment” will be held online weekly using ZOOM.The topics of this online seminar series cover broad aspects of hot and dense QCD matter, with an emphasis on physics related to RHIC beam energy scan (BES) program.
The sixth season of the series will take place
Before Mar. 12th: 10pm (Beijing)=11:00pm (Tokyo)=7:30pm (New Delhi)=3:00pm (Frankfurt) =6:00 am (San Francisco)=9:00 am (New York)
After Mar. 12th: 9pm (Beijing)=10:00pm (Tokyo)=6:30pm (New Delhi)=2:00pm (Frankfurt) =6:00 am (San Francisco)=9:00 am (New York)
on Tuesdays between Mar. 7th and July. 11th, 2023.
Schedule
Mar. 7th
Experimental results from the RHIC beam energy scan program and future outlook
Bedangadas Mohanty (NISER, India)
Abstract:
We will discuss selected results related to the QCD phase diagram, hyperon polarization, spin alignment of vector mesons and nuclei production from the RHIC beam energy scan program. These topics motivate continuing the dedicated experimental programs in the high baryon density regime.
Chair: Nu Xu (LBNL)
Mar.14th
Title: Dense nuclear matter equation of state of from heavy-ion collisions
Agnieszka Sorensen (INT)
Abstract: Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few MeV to well above a hundred MeV. Consequently, properties of strong interactions probed in heavy-ion collisions are complementary to those enabled by studies of nuclear structure and neutron stars or neutron star mergers. However, robust interpretations of experimental results require further developments in modeling. In this talk, I will discuss the status of efforts to constrain the dense nuclear matter equation of state at intermediate energies. I will also outline developments in state-of-the-art models necessary to fully utilize the potential of the forthcoming wealth of data from the BES-II program at RHIC, from GSI and FAIR, as well as from FRIB and future FRIB400.
Chair: Ulrich Heinz (OSU)
Slides Recording (Part A, Part B)
Mar. 21st
Title: Dynamics and dissipation in neutron star mergers
Mark Alford (WUSTL)
Abstract: Neutron star mergers, like heavy ion collisions, are a direct probe of hot and dense nuclear matter. The merger causes dramatic changes in temperature and density that happen in milliseconds, thereby probing dynamical properties that may help us uncover the phase structure of ultra-dense matter. I will describe some of the relevant material properties, focusing on beta equilibration and its consequences such as bulk viscosity.
Chair: Thomas Schaefer (NCSU)
Mar. 28th
Hard Probe, no seminar
Apr. 4th
Heavy ion collisions from 5 TeV down to 4 GeV in the EPOS4 framework
Klaus Werner (Subatech)
Abstract: The EPOS4 project is an attempt to construct a realistic model for describing relativistic collisions of different systems (from proton-proton (pp) to nucleus-nucleus (AA)) at energies from several TeV per nucleon down to several GeV. We argue that a parallel scattering formalism (as in EPOS4) is relevant for primary scatterings in AA collisions above 4 AGeV, whereas sequential scattering (cascade) is appropriate below. We present briefly the basic elements of EPOS4, and then investigate heavy ion collisions from 5.02 TeV down to 4 GeV, to understand how the physics changes with energy, studying in particular the disappearance of the fluid component at low energies.
Chair: Dirk Rischke (Frankfurt)
Apr. 11th
Easter holiday, no seminar
Apr.18th
From QED to QCD: Discoveries and Applications with Polarized Photons
Daniel Brandenburg (OSU)
Abstract: Only a handful of fundamental interactions between light and matter are allowed by the theory of quantum electrodynamics, almost all of which have been observed in the 80+ years since their prediction. Among the lowest-order interactions, only the Breit-Wheeler process, the simplest mechanism for converting 'light quanta' into matter and antimatter, eluded observation for nearly a century.
In this talk I will present the recent discovery of the Breit-Wheeler process by the STAR collaboration achieved by harnessing photons manifest from the ultra-Lorentz boosted Coulomb fields of colliding heavy nuclei. The discovery of the Breit-Wheeler process also provides a novel tool for studying the gluon distribution of heavy nuclei at high energies and helps resolve a decade long puzzle -- the anomalously large nuclear radii extracted from photonuclear interactions in heavy-ion collisions. By utilizing a polarization sensitive technique in photonuclear interactions that was developed for the Breit-Wheeler process, it is possible to measure the radii of large nuclei at high energy to sub-femtometer precision and resolve this two-decade old puzzle. Finally, I'll describe how solving this puzzle in nuclear physics reveals a novel phenomenon in quantum mechanics with potentially far-reaching implications.
Chair: Zhangbu Xu (BNL)
Apr. 25th
Dileptons and BES physics
Frank Geurts (RICE)
Abstract:
Electromagnetic signals such as dileptons are excellent tools to probe the strongly interacting medium created in heavy-ion collisions. Their minimal interactions with the medium and long mean free paths give us experimental access to various physical sources throughout the entire evolution of the system. Studying the invariant mass spectra can help to disentangle these sources and provide information on, e.g., in-medium spectral functions, the lifetime of the system, and temperature measurements at different stages of the evolution. In this talk, we review the application of dilepton measurements, recent results in the context of the RHIC BES program, and the prospect of future measurements.
Chair: Chun Shen (WSU)
May. 2nd
Heavy flavor in QCD matter and lattice
Alexander Rothkopf (U. Stavanger)
Abstract: In this talk I will review recent lattice QCD studies, which elucidate the physics of in-medium heavy quarkonium, touching upon the complex heavy quark potential, in-medium meson spectral functions and heavy-quark related transport coefficients. While progress is being made in generating high precision simulation data, a major challenge remains in the need to extract spectral functions via an ill-posed inverse problem to access phenomenologically relevant real-time dynamics. Recent studies combine both direct reconstruction methods, as well as effective field theory guided spectral modeling to tackle this challenge.
Chair: Claudia Ratti (U. Houston)
May. 9th
Topical discussion on vector meson spin alignment in HIC
Presentation 1: Measurement of global spin alignment of vector mesons at RHIC
Subhash Singha (IMP, CAS)
In non-zero impact parameter heavy-ion collisions, a large initial orbital angular momen- tum (OAM) can be present. Such a large OAM can induce a non-vanishing polarization for hadrons with non-zero spin. The global spin alignment of vector mesons is quantified by the 00th element of the spin density matrix (ρ00) with respect to the quantization axis, i.e. normal to the reaction plane. It can offer information on the spin-orbital interactions of the QCD medium. In this talk, we will present the transverse momentum (pT ), collision centrality, and beam energy dependence of ρ00 for φ and K∗0 vector mesons in RHIC Beam Energy Scan Au+Au collisions at √sNN = 11.5 - 200 GeV. The ρ00 of φ meson is unex- pectedly large, while that of K∗0 is largely consistent with non-polarization baseline. The pattern and magnitude of φ meson ρ00 can not be explained by conventional mechanisms but may be attributed to the influence of a vector meson strong force field. The measure- ment of the global spin alignment can potentially reveal information about the strong force field as well as the spin dynamics of the QCD medium.
Presentation 2: Vector meson polarization from pp to Pb-Pb collisions at the LHC
Luca Micheletti (INFN)
Polarization measurements represent an important tool for understanding the particle production mechanisms occurring in proton–proton collisions. In particular, for quarkonium states, the very small polarization measured at the LHC represents a serious and a long-lasting challenge for theoretical models.
When considering heavy-ion collisions, particle polarization could also be used to investigate the characteristics of the hot and dense medium (Quark- Gluon Plasma) created at LHC energies. Recently, it has been shown that light vector mesons produced in Pb–Pb collisions are polarized, an effect likely due to the presence of a large angular momentum of the strongly interacting system produced in non-central heavy-ion collisions, because of spin-orbital coupling. It has also been conjectured that quarkonium states could be polarized by the strong magnetic field generated in the early phase of the evolution of the system.
In this talk the latest polarization measurements at LHC will be presented, focusing on light vector mesons and quarkonia and providing an overview on the perspectives for this specific observable.
Chair: Jinfeng Liao (U. Indiana)
Slides (Presentation 1 Presentation 2) Recording
May. 16th
Ab initio lattice simulations for nuclear structure and heavy-ion collision initial states
Dean Lee (MSU)
Abstract:
This talk presents the concepts and methods of ab initio nuclear lattice simulations. The starting point is chiral effective field theory implemented on a three-dimensional spatial lattice. Auxiliary-field Monte Carlo simulations allow us to compute the many-body correlations of nucleons from first principles. I discuss the cluster substructures and shape deformations that emerge from these calculations and their significance for ultrarelativistic collisions. I also outline a workflow in the future where ab initio nucleonic configurations with full A-body correlations can be made available for heavy-ion collision initial states.
Chair: Jiangyong Jia (StonyBrook)
May. 23th
On the road to quantum simulating QCD
Zohreh Davoudi (Maryland)
Abstract: A successful program called lattice Quantum Chromodynamics (QCD) has enabled a first-principles look into certain properties of hadrons, nuclei, and thermal matter with the aid of classical computing. At the same time, we have yet to come up with a more powerful computational tool to predict, from the underlying QCD interactions, phases of matter in its densest form and complex dynamical processes after the Big Bang and in heavy-ion collisions. Can a large reliable (digital or analog) quantum simulator eventually enable studies of the strong force? What does a quantum simulator have to offer to simulate QCD, and how far away are we from such a dream? In this talk, I will describe a vision for how we may go on a journey toward quantum simulating QCD, by taking insights from early to late developments of lattice QCD and its achievements, by motivating the need for novel theoretical, algorithmic, and hardware approaches to quantum-simulating this unique problem, and by providing examples of the early steps taken to date in establishing a quantum-computational lattice-QCD program.
Chair: Longgang Pang (CCNU)
May. 30th
Topical discussion: Light nuclei and hyper-nuclei productions
Presentation 1: Hyper-)nuclei production and the coalescence—correlations relation
Kfir Blum (Weizmann)
Abstract:
The mass number scaling of the yields of hadrons in hadronic collisions begs for a first-principle explanation. Thermal models famously fit this scaling, with only O(1) inaccuracy over some 9 orders of magnitude in yield, but these fits are arguably not basic theory. Nuclear coalescence suggests a way forward, in the sense that it allows information on the phase space of nucleons at kinetic decoupling to be converted into an approximate first-principle prediction for nuclei yields. The nucleon phase space is constrained by correlation analyses (femtoscopy). I discuss the coalescence—correlations relation, highlighting theoretical predictions and uncertainties. I also comment on recent measurements, notably (i) experimental analyses designed to put coalescence and correlations on equal footing, and (ii) measurements of hyper-triton production in small systems.
Presentation 2: Light Nuclei and Hypernuclei Production in Heavy-Ion Collisions - Recent Experimental Results and Future Prospects
Yue Hang Leung (Heidelberg)
In heavy-ion collisions, light nuclei and hypernuclei production have been suggested to be sensitive to local baryon density fluctuations and baryon-strangeness correlations respectively, and may be utilized to study the QCD phase diagram. However, our understanding of the production mechanisms of nuclei in heavy-ion collisions remain incomplete; it remains a mystery how such weakly bound states survive the hot and dense medium. A solid understanding on their production mechanisms is essential in order for us to use them to extract information relevant to the QCD phase diagram. Meanwhile, measurements on the intrinsic properties of hypernuclei, such as their lifetimes and binding energies, can provide constraints to the hyperon-nucleon interaction, which is an essential ingredient in the equation-of-state of high baryon density matter.
In this talk, recent experimental measurements on light nuclei and hypernuclei production in heavy-ion collisions will be presented, with a focus on the STAR Beam Energy Scan. These measurements will be compared to various model calculations and implications on their production mechanisms will be discussed. Recent measurements on the intrinsic properties of hypernuclei will also be shown. Future prospects on furthering our understanding of the QCD phase diagram and the nuclear equation-of-state at high baryon density with light nuclei production will be discussed.
Chair: Che-Ming Ko (TAMU)
Slides (Presentation 1 Presentation 2) Recording
June. 6th
Thermalization and collectivity in small and large systems
Aleksas Mazeliauskas (Heidelberg)
Abstract:
Heavy-ion collisions at BNL’s Relativistic Heavy Ion Collider and CERN’s
Large Hadron Collider provide strong evidence for the formation of a quark-gluon plasma. Effective weak-coupling QCD descriptions and strong-coupling holographic approaches support the rapid thermalization picture in large collision systems. The outstanding question in QCD is whether the hydrodynamically-flowing quark-gluon matter forms in even smaller collision systems. On the opposite end of the energy scale, the emerging collectivity in strongly-correlated few-body systems can also be studied in table-top experiments with ultracold atomic gases. In this talk, I will review the state of the art of QCD thermalization studies and identify promising connections with cold-atom experiments.
Chair: Soeren Schlichting (Bielefeld U.)
Jun. 13th
Three body interactions studied at the LHC
Abstract
After the successful application of femtoscopy to pp and pPb collisions at the LHC to study the residual strong force among hadrons, we have moved the focus of our research to three body systems.
In this talk I will present the results obtained in the study of three nucleons systems, Kaon proton proton and Lambda proton proton systems discussing the challenges and future plans .
Laura Fabbietti (TUM)
Chair: Scott Prat (MSU)
Jun. 20th
Initial Stages, no seminar.
June. 27th
ALICE 3 - A new horizon for QCD
Abstract
The ALICE detector was built to study many-body Quantum Chromo-Dynamics (QCD) at high temperature and effectively zero baryon density, using relativistic heavy-ion collisions at the Large Hadron Collider (LHC). These collisions form the Quark Gluon Plasma (QGP), a state of matter where quarks and gluons are no longer confined inside hadrons. The ALICE physics program centers around the key questions related to QGP phenomena. These include the macroscopic and microscopic properties of the QGP, and the details of the QGP phase transition to hadrons, that is believed to have taken place in the early Universe. At the same time, ALICE’s versatile setup allows for the study of pp collisions, p–Pb collisions, and ultra-peripheral collisions. The associated studies serve as deep probes of cold nuclear matter, and allow for investigations of stellar and interstellar phenomena. The ALICE Collaboration plans a major upgrade of its detector, referred to as ALICE 3. ALICE 3 is proposed for physics data-taking in the LHC Run 5 (starting 2035) and beyond. I will discuss the proposed physics program, detector concept, and expected physics performance.
Anthony Timmins (U. Houston)
Chair: Daicui Zhou
July. 4th
Independence day, no seminar
July. 11th
The Quest to Understand the Fundamental Structure of Matter and the Realization of ePIC
Rolf Ent (JLab)
Chair: Bowen Xiao (CUHK)
Registration:
The interested participants are kindly requested to register through "registration" on the left side of the indico page. By attending this event you agree that the seminar and discussion being recorded and posted on the seminar web site.
Organizers:
Heinz, Ulrich (OSU) heinz.9@osu.edu
Luo, Xiaofeng (CCNU) xfluo@ccnu.edu.cn
Ratti, Claudia (UH) cratti@central.uh.edu
Song, Huichao (PKU) huichaosong@pku.edu.cn
Xu, Nu (LBNL) nxu@lbl.gov
Yin, Yi (IMP) yiyin@impcas.ac.cn
Previous series:
Code of Conduct :
The organizers are committed to making this seminar series productive and enjoyable for everyone. Creating a supportive professional environment where open and frank discussion of ideas can take place, where everyone is treated with courtesy and respect, and in which diversity and inclusion are valued is the responsibility of all the participants. We will not tolerate harassment of attendees or others involved in the conference in any form. By joining the Zoom call, you agree to follow these guidelines:
1) Behave professionally in personal interactions. Harassment and sexist, racist, or exclusionary comments or jokes are not appropriate. Harassment includes sustained disruption of talks or scientific discussions, deliberate intimidation, stalking, offensive comments related to gender identity, sexual orientation, disability, physical appearance, body size, race, nationality, or the religion or non-religion of participants.
2) Be kind to others. Do not insult or put down the speaker or the other attendees. Scientific discussion and criticism is vital and should be conducted in this spirit.
3) All communication should be appropriate for a professional audience including people of many different backgrounds.
Should a participant be asked to stop any inappropriate behavior, they are expected to comply immediately. In serious cases, they may be muted or asked to leave the meeting at the sole discretion of the organizers.
