STAR Correlations and Fluctuations PWG

[Takafumi Niida <niida AT bnl.gov>]

Date: 3/10/2023

Participants: Ho San Ko, Ashish Pandav, Nu Xu,
Hanna Zbroszczyk, Barbara Trzeciak, Maria Zurek, Md. Nasim, Ting Lin, 
Toshihiro Nonaka, Yi Yang, Yue-Hang Leung, Zhenyu Chen, Rongrong Ma, Takafumi 
Niida

Title: Charged Particle Multiplicity Dependence of the Net-Proton 
Distributions in sqrt{sNN} = 200 GeV Ru+Ru and Zr+Zr Collisions
PAs: Ho San Ko, Xin Dong, ShinIchi Esumi, Ashish Pandav, Nu Xu, Yu Zhang
Target journal: PLB
Proposal page: 
https://drupal.star.bnl.gov/STAR/blog/hsko/Paper-Proposal-200-GeV-isobar-collisions-net-proton-fluctuation-analysis
Presentation: 
https://drupal.star.bnl.gov/STAR/system/files/Isobar_net_proton_high_moment_analysis_paper_proposal_PWGC_preview.pdf

The PWGC panel previewed a paper proposal from CF PWG. The panel found that 
analysis is mature and results are interesting, and recommends that the paper 
should move forward with the comment that the physics conclusion should be 
sharpened focusing more on isobar data. The following points were discussed.


Q. In conclusions, PAs mention that high multiplicity (HM) pp result and 
central AA are consistent with LGT model. But HM pp and peripheral AA are 
consistent within their uncertainties. Does it somehow contradict? Do PAs 
mean QGP is formed in pp and all centrality of AA?
A. QGP could be formed in HM pp. Currently uncertainty is large but it can be 
further checked with run25 pp data. We try to say that the overall decreasing 
trends of the cumulant ratios from positive to negative toward high 
multiplicity, which approach Lattice QCD calculations, indicates the creation 
of thermalized medium. We also refer to the ongoing GPC paper for pp.
C. In Fig. 4, it is true for C4/C2 but C5/C1 and C6/C2 don’t show the trend 
with given uncertainties. Isobar central data look consistent with peripheral 
data. It would be nice to zoom-in y-axis more if there is such a trend. All 
possible explanations should be discussed in the paper.

Q. In Fig. 4, have you checked what the significance of the decreasing trend 
is?
A. Haven’t calculated the significance but we fitted the data with polynomial 
function as seen in slide 19.
C. If you want to mention the decreasing trend, it would be better to say so 
quantitatively.

Q. C4/C2 and C6/C2 seem to show the decreasing trend while C5/C1 doesn’t. Any 
intuitive explanation?
C. Likely due to statistical fluctuations

Q. In Fig. 4, three systems are compared. We guess PAs applied the kind of 
relative efficiency to refmult3 on x-axis. Could you explain a bit?
A. For Isobar and AA, we haven’t corrected for the efficiency. As shown in 
slide 17, the effect is ~14% which doesn’t change the picture in Fig. 4. For 
pp collisions, efficiency is ~90% difference. So the x-values for pp were 
corrected for the effect.
C. It’s not a fair comparison. Since all the embedding data are there, why 
PAs don’t correct for the efficiency, which should be more fair and no 
confusion among the different systems. Please think about the data 
presentation in a better way.

C. Embedding reproduction was done for isobars with some tunings. The effect 
may be small but please check and make sure that the results don’t change.
A. Will do so.

Q. Have you presented your centrality definition in centrality meeting? It 
would be better to make an official record.
A. No, PAs will do so.

Q. HRG was compared to the data in Fig. 3 but there was no mentioning. What 
is the conclusion?
A. The data are far away from the unity which HRG and Grand Canonical cannot 
describe the data.
C. In the paper, please mention something if it’s in the figure.