STAR Flow, Chirality and Vorticity PWG

[webmaster AT star.bnl.gov]

Dear star-fcv-l AT lists.bnl.gov members,

Subhash Singha ( connectsubhash AT gmail.com ) has commented on a material  
originally submitted by Tan Lu ( lut AT impcas.ac.cn ) at
https://drupal.star.bnl.gov/STAR/presentations/Quark-Matter-2025/Measurements-global-and-local-spin-polarization-hyperons-AuAu-collis

Comment:
Dear PAs,

Nice abstract. Here is my attempt to rephrase it, I tried to make it read  
smoother. Please feel free to edit/add/remove texts as necessary:

"In non-central heavy-ion collisions, substantial angular momentum is  
generated, resulting in significant vorticity and the spin polarization of  
particles with finite spin along the global angular momentum (called P_y).  
Additionally, anisotropic flow can produce local vorticities in both in-plane 
 
(z) and out-of-plane (y) directions, leading to what is known as local  
polarization. The RHIC Beam Energy Scan-II (BES-II) program, including the  
Fixed-Target (FXT) mode at STAR, provides a unique opportunity to investigate 
 
hyperon global polarization (Λ, Λ̅, Ξ, and Ω) over a wide range of  
baryon chemical potentials. This study probes the vortical characteristics of 
 
the medium and can serves as a tool for exploring the nuclear matter equation 
 
of state. The second harmonic of local spin polarization (P_{2y} and P_{2z})  
for Λ and Λ̅, and their differences, is predicted to be a sensitive probe  
for the spin Hall effect driven by gradients in baryon chemical potential.

In this talk, we present measurements of the global polarization of Λ, Λ̅, 
 
Ξ, and Ω at √sNN = 7.7–27 GeV in BES-II Au+Au collisions and the global 
 
Λ polarization at √sNN = 3.0–6.2 GeV in FXT Au+Au collisions.  
Additionally, we report on the second harmonic of the local Λ and Λ̅  
polarization and their differences in BES-II Au+Au collisions at √sNN =  
7.7–27 GeV. These measurements provide valuable insights into the spin  
dynamics within the QCD medium produced in heavy-ion collisions."

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