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Paper proposal of v0(pt) in Au+Au and O+O at 200 GeV

Updated on Tue, 2025-08-05 22:09 by chunjian. Originally created by zainingwang on 2025-07-25 09:40.

Title:  Probing the nature of radial flow in thermalized QGP droplet from large to small system at 200 GeV

PA: Zaining Wang (PA Representative), Chunjian Zhang, Jiangyong Jia, Jinhui Chen, Shengli Huang, Yiming Xu, Shusu Shi, Guoping Wang, Yuli Kong, Pandav Ashish, Bappaditya Mondal, Prabhupada Dixit.

Analysis note:  Nearly complete

Paper draft: In progress

Target Journal: Physical Review Letters

PWG presentation:

  1. 06/18/2025 (Preliminary request, Crossing behaviors)  drupal.star.bnl.gov/STAR/system/files/FCV_updatev0ptAuAu200_0618.pdf
  2. 05/07/2025 (For energy and system comparison) drupal.star.bnl.gov/STAR/system/files/FCV_v0ptupdate_2025_0507.pdf
  3. 03/26/2025 (For model EoS study) drupal.star.bnl.gov/STAR/system/files/FCV_v0pT_update_Zaining_2025_3_19.pdf
  4. 03/12/2025 (For model PID study) drupal.star.bnl.gov/STAR/system/files/v0pT_update_2025_3_12.pdf
  5. 03/05/2025 (Comparison of different Runs)v0pT_update_2025_3_5.pdf
  6. 01/22/2025 (Measurements, |\delta\eta|dependence, refpTrange) drupal.star.bnl.gov/STAR/system/files/v0pT_2025_1_22.pdf
Abstract:

The expansion dynamics and medium properties of the quark-gluon plasma (QGP) are fundamental to understanding the nature of the fluid. We present a novel observable, v0(pT), probing the collective nature of radial expansion at 200 GeV RHIC energies for the first time. We measure the transverse momentum (pT) dependence of v0(pT) using a two-particle correlation method from large Au+Au to small O+O collisions. This long-range transverse momentum correlation shows the factorization and centrality-independent shape in pT. We also observe the characteristic mass ordering in identified hadrons at low pT and non-linear saturation behavior in the jet-quenching dominated regime at high pT. Furthermore, we also compare the state-of-the-art hydrodynamics. This work advances efforts to further constrain initial conditions and provides new insights into the nature of radial flow in thermalized QGP droplets across collision sizes.

 

Figure 1:
 

The integral v0 illustrates the global behavior of radial flow fluctuations. By comparison of Au+Au and O+O, it can be seen that v0, as a behavior of global radial flow fluctuations, scales with 1/√N.

Figure 2: 



The v0(pT) in (a) Au+Au at 200 GeV, (b) O+O at 200 GeV and v0(pT)/v0 in (c) Au+Au at 200 GeV, (d) O+O at 200 GeV. Centrality dependence and crossing point, showing the behavior of this observables. High-pT exist a drop, potential jet-quenching. After scaling by intergral v0, different centralies stay on top of each other. The scaling fails at pT larger than 2 GeV/c due to potential jet quenching effect. 

Figure 3:


The v0(pT) in (a) Au+Au 0-10% at 200 GeV, (b) Au+Au 40-50% at 200 GeV, (c) O+O 0-10% at 200 GeV, (d) O+O 40-50% at 200 GeV. Compred to the model calculations from 3DGlauber+MUSIC+ISS+UrQMD. Data model comparison shows a consistency.

Figure 4:

The v0(pT) of pid in (a) Au+Au 0-10% at 200 GeV, (b) Au+Au 40-50% at 200 GeV, (c) O+O 0-10% at 200 GeV, (d) O+O 40-50% at 200 GeV. With model comparison. Mass ordering is clear at low-pT regions. Particles experience different radial flow at low-pT region. The crossing points are determined by the mean pT of the particle.

Summary

In summary, the measurement of radial flow v0(pT) is performed by STAR experiment at the RHIC in Au+Au and O+O collisions at √(S_NN ) = 200 GeV. We observed the factorization and centrality-independent shape in pT in this long-range transverse momentum correlation without the influences from particle selection eta gaps and reference pT ranges. Interesting, one expects the characteristic mass ordering in PID due to the QGP radial expansion and clear size dependence. A precise comparison with the state-of-the-art 3D-Glauber+MUSIC+UrQMD hydrodynamic model constrains the initial conditions of QGP and indicates the EoS sensitivities to its radial expansion. This study provides new insights into the nature of radial flow in thermalized QGP droplets across collision sizes at RHIC energies.

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