Bulletin of the American Physical Society
6th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Sunday–Friday, November 26–December 1 2023; Hawaii, the Big Island
Session M14: Relativistic Heavy Ions III |
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Chair: Takafumi Niida Room: Hilton Waikoloa Village Kohala 4 |
Friday, December 1, 2023 2:00PM - 2:15PM |
M14.00001: Signals of initial state quantum entanglement in relativistic particle collisions Rene Bellwied I will show thermodynamic entropy calculations based on charged particle multiplicity data from proton-proton collisions at the LHC in comparison to entanglement entropy calculations based on initial state gluon distributions. The commonalities between the initial and final state distributions suggest that entanglement could be a possible source for the seemingly thermal and collective behavior in small systems. I will pose the question on when such a picture could and will break down due to decoherence of the initial state. I will also try to show that a rather simple final state measurement should be sensitive to gluon saturation, in particular when properly binned in rapidity space. |
Friday, December 1, 2023 2:15PM - 2:30PM |
M14.00002: Tracking the baryon quantum number with heavy-ion collisions Chun Yuen Tsang The baryon number is a conserved quantity in quantum chromodynamics (QCD), which is conventionally thought to be shared equally among the valence quarks in baryonic matter. However, an alternative theory suggests that the baryon number is carried by a non-perturbative, Y-shaped topology of gluons connecting to three quarks. This topology is called the baryon junction. Neither theory has been experimentally verified yet. The STAR Collaboration reports here two pieces of experimental evidence which collectively indicate that valence quarks do not carry baryon numbers. |
Friday, December 1, 2023 2:30PM - 2:45PM |
M14.00003: Charge-dependent anisotropic flow in relativistic resistive magneto-hydrodynamic expansion Chiho Nonaka, Nicholas J Benoit, Takahiro Miyoshi, Hiroyuki Takahashi, Kouki Nakamura We have investigated the charge-dependent anisotropic flow in high-energy heavy-ion collisions, using relativistic resistive magneto-hydrodynamics (RRMHD). First, we construct a relativistic resistive magneto-hydrodynamic (RRMHD) numerical simulation code for high-energy heavy-ion collisions.We confirm that our code reproduces well the results of standard RRMHD tests in the Cartesian coordinates and in the Milne coordinates. Next, we apply our RRMHD code to analysis of the charge-dependent anisotropic flow in high-energy heavy-ion collisions.We consider the optical Glauber model as an initial model of the quark-gluon plasma (QGP) and the solution of the Maxwell equations with source term of the charged particles in two colliding nuclei as initial electromagnetic fields. The RRMHD simulation is performed with these initial conditions in Au-Au and Cu-Au collisions at sqrt{sNN} = 200 GeV. We have calculated the charge-odd contribution to the directed flow Δv1 and elliptic flow Δv2 in both collisions based on electric charge distributions as a consequence of RRMHD. We conclude that the charge-dependent anisotropic flow is a good probe to extract the electrical conductivity of the QGP medium in high-energy heavy-ion experiments. |
Friday, December 1, 2023 2:45PM - 3:00PM |
M14.00004: Construction of the sPHENIX Detector and Performance from Its First Year of Operation Edward J O'Brien sPHENIX is the first new major detector at the Relativistic Heavy Ion Collider at BNL in over twenty years. Its design has been optimized to measure a comprehensive set of jet, open heavy flavor and upsilon observables with both large statistics and broad kinematic reach in RHIC collisions of AA, pA and pp. The detector is composed of a set of hadronic and EM calorimeters, tracking subsystems, strip and pixel silicon detectors, and trigger detectors readout through a fast, high-bandwidth Data Acquisition system. At the detector’s core is a 1.4 T superconducting solenoidal magnet formerly of the BaBar experiment. Construction of sPHENIX was completed in April 2023, and sPHENIX has commissioned and taken first data in the RHIC 2023 Run. This talk will discuss the challenges associated with building sPHENIX during a global pandemic, the race to complete sPHENIX assembly before the start of the RHIC run, and the performance of sPHENIX during its first year of operation at RHIC. |
Friday, December 1, 2023 3:00PM - 3:15PM |
M14.00005: Exploring a high-density regime in the QCD Phase diagram at J-PARC Heavy-Ion Project (J-PARC-HI) Hiroyuki Sako J-PARC (Japan Proton Accelerator Research Complex) is one of the world’s highest-intensity proton accelerators for material and life sciences, neutrino physics, and hadron and nuclear physics in the GeV energy range. We are planning a future project, J-PARC-HI, to accelerate world's highest-intensity heavy-ion beams at J-PARC. For the acceleration scheme, a new heavy-ion linac and a booster ring are required as an injector, while the heavy-ion beams can be accelerated in the existing 3-GeV synchrotoron (RCS) and 30-GeV synchrotoron (MR) . The maximum beam rate is expected to reach 1011 Hz, which is the world's highest intensity for the heavy-ion beam, and the energy can vary from 1 to 12 AGeV/c. We will explore QCD phase structures in a high-baryon density regime such as the first-order phase boundary, the QCD critical point, and QCD superconducting phases with various probes such as event-by-event fluctuations, dileptons, collective flow, and two-particle correlations. We also search for various multi-strangeness particles/nuclei and study hadron-hadron interactions including strangeness. In this talk, we introduce the overview of J-PARC-HI including the staging strategy with a low-intensity injector and an experiment at the existing J-PARC E16 spectrometer (Phase 1), and with a high-intensity injector and an experiment with a new large acceptance spectrometer (Phase 2). We show the status of the dilepton measurements in a p+A collisions at J-PARC E16 which serves as a baseline experiment for J-PARC-HI. Then, we will show some of the physics feasibility for dilepton and hadron measurements at J-PARC-HI. |
Friday, December 1, 2023 3:15PM - 3:30PM |
M14.00006: Acceleration of Heavy-Ion Beams at J-PARC kazuhiro Tanaka In the development of nuclear physics in Japan, research using so-called high-energy heavy ion beams of 10 GeV per nucleon or more has been a research vacuum due to the lack of facilities in Japan to accelerate such beams and conduct experiments. |
Friday, December 1, 2023 3:30PM - 3:45PM |
M14.00007: ALICE 3 - A new horizon for QCD Anthony Timmins 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. |
Friday, December 1, 2023 3:45PM - 4:00PM |
M14.00008: sPHENIX MVTX Commissioning at BNL Zhaozhong Shi sPHENIX is a new state-of-the-art heavy-ion physics experiment at RHIC in the past 20 years. At the center of the sPHENIX detector, the Monolithic-Active-Pixel-Sensor (MAPS) based VerTeX detector (MVTX) is a high-precision silicon pixel detector adapted from the ALICE Inner Tracking System. The MVTX provides excellent position resolution and the capability of operating in continuous streaming readout mode, allowing precise vertex determination, and recording a large data sample, both of which are particularly crucial for heavy flavor physics measurements. The MVTX has been installed to the sPHENIX detector on April 1 and passed all tests. sPHENIX has completed its first year Au + Au collision data taking from May 18 to August 1. During the run, a significant background, potentially linked to beam halo, is observed by the MVTX. Notably, ALICE also reported similar issues at the LHC in Run 2023 and found a solution with the LHC accelerator division. In addition, cosmic data were collected for calibration and alignment purposes. This presentation will cover the commissioning and performance of the MVTX detector. We will also discuss various aspects, including studies on MVTX raw data processing, beam background, noise levels, and tracking alignment. |
Friday, December 1, 2023 4:00PM - 4:15PM |
M14.00009: Developments in Entanglement Enabled Spin Interference James D Brandenburg Photonucelar processes have been understood for decades to be a golden channel for performing tomography of the gluon density and spatial distribution within nucleons and nuclei. The recent discovery of entanglement enabled spin interference in the angular distribution of $ ho^0 ightarrow pi^+pi^-$ from diffractive photonuclear interactions has opened new avenues for investigating the gluon distributions in heavy nuclei. However, the mechanism enabling this interference effect is still being investigated. In this talk I will summarize the current observations based on experimental results from multiple collaborations. Next, I will discuss the available theoretical models along with the implications for the future studies of gluon tomography in heavy ion collisions. Finally, I will discuss potential explanations for the entanglement enabling this novel form of interference. |
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