STAR Flow, Chirality and Vorticity PWG

[Takafumi Niida <niida AT bnl.gov>]

Date: 5/28/2021

Participants: Prabhupada Dixit, Shaowei Lan, Md. Nasim, Shusu Shi,
Barbara Trzeciak, Daniel Brandenburg, Daniel Cebra, ShinIchi Esumi, Hanna 
Zbroszczyk, Maria Zurek, Matt Posik, Prithwish Tribedy, Qinghua Xu, Raghav 
Elayavalli, Hanseul Oh, Yi Yang, Rongrong Ma, Takafumi Niida

Title: Elliptic and triangular flow of (multi-)strange hadrons in Au+Au 
collisions at sqrt(sNN) = 54.4 GeV
PAs: Prabhupada Dixit, Shaowei Lan, Md. Nasim, Shusu Shi
Target journal: PRC
Proposal page: https://www.star.bnl.gov/protected/lfsupc/nasim/webpage_54gev/
Presentation: 
https://drupal.star.bnl.gov/STAR/system/files/paper_proposal_54gev_pwgc_0.pdf

The PWGC panel previewed the paper from FCV PWG. The panel found that the 
analysis is mature and the paper should move forward with the proposed 
journal. Physics conclusions should be strengthen with possible comparisons 
with theoretical models. The following points were discussed during the 
meeting.

s2: Do proton and phi v2 cross at high pT? Even at 1.5 GeV, the ratio looks 
below 1.
A. Yes, it crosses at higher pT, like >2 GeV.

s8: The total systematic uncertainties look larger than rough estimate from 
each plots. Please double-check.
A. PAs will check again.

Fig. 5: 
Q. The choice of fitting to Ks0 has any physics oriented reason? Depending on 
which particle you choose, the visibility will look quite different.
A. Most precise data, i.e. K0s, was selected for baseline.

Q. NCQ scaled Lambda v3 is deviated from the global trend at low pT (not so 
significant at v2). Any intuitive explanation?
A. Not really. PAs are also not sure if the feed-down is responsible for it.

C. Especially the lower is crowded. Please consider to draw Lambda and K0s in 
3rd panel for better visibility.

Fig. 6 and 7: Why there is difference between particles and anti-particles in 
general?
A. Transport quarks would have more interactions since they exist in the 
initial state, which leads to larger flow, while anti-particles contain more 
produced quarks (anti-quarks). 
C. See arXiv:1107.3078 by Jamie, Mike and Paul.

Fig. 9:
Q. "Mass ordering violation” comes from 1 lowest data point with only ~1sigma 
effect, right?
A. Yes. Therefore PAs used the word “Hint”.

Q. The ratio for more central data is smaller. Should we expect this?
A. protons are more affected by hadron rescattering and therefore the ratio 
becomes smaller

Q. There is centrality dependence at 54 GeV but no energy dependence compared 
to 200 GeV. Should we expect larger for 200 GeV?
A. There will be competing effects between partonic and hadronic 
interactions. At higher energy, partonic interaction would become large.

Q. Why anti-proton was chosen here while proton was used in previous study as 
shown in slide 2?
A. At 200 GeV, almost no difference between p and pbar. At 54 GeV, to avoid 
transported protons, pbar was used.

Q. Why 0-10% is not shown while 0-80% data is shown in the right panel? 
A. Due to large error for phi, PAs didn’t include it.
C. No reason to hide the data. It would be better to present.

C. Would be better to have pi, K, p in Fig. 9 as well as in other figures.
A. pi, k, p data are ongoing with another GPC with 3 GeV. Will check the 
status with Shaowei.

Q. Any plan to have model comparison? 
A. Currently no. 
C. PAs should ask theorists and see if the calculations can be obtained 
within a reasonable time scale. 

Q. What is the importance to look at 54 GeV?
A. There would be a transition between partonic and hadronic phases and the 
dynamics may also change.