STAR Flow, Chirality and Vorticity PWG

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

Subhash Singha ( connectsubhash AT gmail.com ) has commented on a material  
originally submitted by Charles Robertson ( rober558 AT purdue.edu ) at
https://drupal.star.bnl.gov/STAR/presentations/Quark-Matter-2025/Phi-Meson-Local-Global-and-Helicity-Spin-Alignment-STAR

Comment:
Dear PAs,

Nice abstract. I have a few suggestions for your consideration:

Title: I would suggest something like: Measurement of Global, Local, and  
Helicity Spin Alignment of ϕ-Mesons in High Nuclear Collisions at RHIC
(But in the abstract text you have to clarify what you mean by local)

I would suggest to remove l#2-5: "They are predicted .... physical  
mechanisms."
l#5: "However, a significant ...strong force field []" --> We observed  
unexpectedly large ρ_00 values for ϕ(1020) mesons in the first phase of the 
 
RHIC Beam Energy Scan (BES-I) in Au+Au collisions. These values exceed  
conventional expectations based on global hyperon polarization induced by  
orbital angular momentum, suggesting the possible presence of a strong force  
field for ϕ mesons [].

l#8-11: "Previous measurements ....decay daughter distributions" --> Previous 
 
ρ00 measurements use a 1D angular distribution in θ* (polar angle of the  
daughter kaon in the ϕ meson rest frame relative to the event plane). We  
will use both angular dimensions (theta* and \phistar), enabling off-diagonal 
 
element extraction with fewer assumptions about decay daughter distributions.

l#11-15: "We wil present .... (BES-II)" --> We will present differential  
measurements of ϕ-meson ρ_00 and off-diagonal spin density matrix elements, 
 
using data from the second phase of RHIC BES (BES-II) in Au+Au collisions at  
√sNN = 7.7–19.6 GeV collected by STAR. Results will be shown as functions 
 
of rapidity (y), centrality, and transverse momentum (pT).

l#15-17: "Alongside, ... two from" --> Additionally, we will present  
differential helicity frame spin alignment results to test their predicted  
relation with global spin alignment.
l#18-20: "We will also present ... pair invariant mass" --> We will also  
present ρ_00 results using two alternative extraction methods: (i) ⟨cos2  
θ*⟩ and (ii) ⟨cos 2ϕ*⟩ (where ϕ* is the projection of θ* onto the  
transverse plane) as a function of the kaon pair invariant mass.
l#21-22: I would suggest removing: "We report ... where applicable."
l#23: To me the definition of local is not obvious here, I guess you are  
trying to follow the same convention as used in lambda polarization along  
beam axis, right?

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