STAR Flow, Chirality and Vorticity PWG

[Sooraj Radhakrishnan <skradhakrishnan AT lbl.gov>]

Date: 09/27/2024

Participants: Alex Jentsch, Lanny Ray, Jae Nam, Xiaoxuan Chu, Hanna Zbroszczyk, Prithwish Tribedy, Richard Seto, Isaac Mooney, Nihar Sahoo, Qian Yang, Guannan Xie, Tommy Tsang, Yue Hang Leung, Barbara Trzeciak, Sooraj Radhakrishnan

Title: Test of  the v_{2} Factorization Hypothesis in Au+Au collisions at  sqrt{s_{NN}}=200 GeV at STAR

PAs: Lanny Ray, Alex Jentsch, Prabhat Bhattarai, Elizabeth Oldag

Target journal: PRC

Proposal page: https://www.star.bnl.gov/protected/jetcorr/estruct/ray/FactorizationWebpage/

Presentation:https://drupal.star.bnl.gov/STAR/system/files/Factorization_PWGC_Preview_Talk_1.pdf

The PWGC panel previewed a paper proposal from FCV PWG. The panel found that the analysis is mature and results are important and interesting, and the paper should move forward. The journal choice was also found to be appropriate. The following points were discussed.

Q: On S9, are these models or just functions

A: These are just functions to describe the shape components. These were used also in previous STAR paper

Q: If these functions don't quite reproduce the shapes, won't it affect your conclusions?

A: It could, this is to be evaluated in future studies

Q: Are the PID cuts momentum and eta dependent?

A: Yes, they are, dependent on momentum p and eta

Q: Why are the centrality bins chosen the way as they are in analysis, like 38-46% etc? 

A: This is to compare to previous results published with similar selections. In the earlier analysis, a shift was needed with trigger efficiency causing the bin boundaries to shift 

Q: Does the non-flow subtraction enforce that the factorization holds?

A: No, it doesn't, There are cases where the ratio r is not 1

Q: Do the studies here with mini-jets imply that the typical delta_eta cuts used in analyses are good? 

A: Yes, we can infer so

Q: For the cases where the ratio is different from 1, do you see a dependence on average yt or yt difference? 

A: There doesn't seem to be a strong dependence on yt difference. 

Q: What about the average yt?

A: Yes, we can look into that

Q: What are the different colors for systematic uncertainties?

A:  The uncertainties are extrapolated where the Barlow checks return zero for the systematic variations 

Q: In your fitting, do you have any eta dependence for v2?

A: No. But we did try with eta dependence in the previous study, it has a negligible impact on the results 

--

Sooraj Radhakrishnan

Research Scientist,

Department of Physics

Kent State University

Kent, OH 44242

Physicist Postdoctoral Affiliate

Nuclear Science Division
Lawrence Berkeley National Lab
MS70R0319, One Cyclotron Road

Berkeley, CA 94720

Ph: 510-495-2473

Email: skradhakrishnan AT lbl.gov