STAR Flow, Chirality and Vorticity PWG

[Takafumi Niida <niida AT bnl.gov>]

Date: 10/7/2022

Participants: Cameron Racz, Ding Chen, Erik Loyd, Shinichi Esumi, Richard Seto,Daniel Brandenburg, Daniel Cebra, Barbara Trzeciak, Hanna Zbroszczyk, Maria Zurek, Md. Nasim, Nihar Sahoo, Prithwish Tribedy, Sooraj Radhakrishnan, Subhash Singha, Xiaofeng Luo, Yi Yang, Takafumi Niida, Rongrong Ma

Title: Event Plane Correlated Triangular Flow in Au+Au Collisions at sqrt{s_NN} = 3 GeV

PAs: Cameron Racz, Ding Chen, Erik Loyd, Shinichi Esumi, Richard Seto

Target journal: PRC

Proposal page: https://drupal.star.bnl.gov/STAR/blog/dchen/Event-Plane-Correlated-Triangular-Flow-AuAu-Collisions-sqrtNN3-GeV-0

Presentation: https://drupal.star.bnl.gov/STAR/system/files/v3_3GeV_PWGC_preview_4.pdf

The PWGC panel previewed a paper proposal from FCV PWG. The panel found that the analysis is mature and results are interesting and agree that the paper should go forward. The target journal is appropriate. The following points were discussed.

General:

C. In title, "Event plane correlated triangular flow” is used but it would better to say “Reaction plane correlated triangular flow” or “Rapidity odd triangular flow” as “EP” could be Psi3 or other orders.

A. PAs agree with that.

Q. Is it useful to show any comparison with HADES results?

A. Such a comparison was done internally.

C. Since the conclusion mentions the relation, it may be easy to see by eye in plot(s).

Slide 3:

C. "3.85A GeV” should be quoted as "2.9A GeV” as it is used for the kinetic energy instead of total energy, if you want to compare with HADES “1.23A GeV” that is for kinetic energy.

Slide 4-5:

Q. PAs used bad run list from QA group but the resulting number of events looks smaller than expected. Why?

A. Some of the data were not available when making own trees due to access issue. 

C. Rongrong will talk to S&C to check if this dataset is already duplicated in distributed disk. If not, he will ask them to do so. It should be ~202M events and make sure to be consistent with other analysis/papers.

Slide 10:

Q. Why are deuteron systematic uncertainties relatively small compared to those for protons and tritons.

A. Not sure why. PAs will check the details.

Q. For subevent systematics, did you just change the rings used for reference subevent, not subevent for flow measurement? Have you tired to use EPD B for flow measurement?

A. Right and EPD B has worse resolution.

Slide 19:

Q. Do you understand why triton shows different behavior? Does this mean that the coalescence doesn’t work for triton? Isn’t it consistent with other papers?

A. PAs also do not know the reason but it could be due to different production mechanism like fragmentation rather than coalescence.

C. In light nuclei v1/v2 3 GeV paper, at least v1 shows A-scaling for p/d/t but v2 doesn’t follow the scaling especially for protons.

C. BES-I light nuclei v2 paper also indicates that the scaling doesn’t work at lower energies.

C. There will be significant contribution of the feed-down from excited nuclei at lower energies, which might be related to this behavior. It would be nice if PAs can check the effect using any model.

C. Another possibility is due to quite different acceptance for tritons. Would be good to check pT(or centrality?) dependence for different slice of rapidity

Q. Why do tritons have smaller systematic uncertainties only for mid centrality?

A. Could be due to the combinations of statistics/difference acceptance/smaller signal etc. PAs will check on this.

Q. What is the pileup contribution? Did you study the effect or tried to remove the contribution?

A. Pileup cut was applied but do not know if there is possible contribution.

C. Pileup contribution will be ~1% level in most central events.

Slide 23:

Q. Was tracking efficiency applied for pT-integrated v3 results?

A. Yes for p/d/t but not for pions/kaons since they are close to zero.

C. Understood but since the data are presented and compared to theoretical calculations it would be still good to correct for it.

Q. How the epsilon was calculated in JAM? Are they initial epsilon?

A. No, they are final epsilon. We picked up particles around t=50 fm/c and calculated epsilons.

Q. How did you choose the models (JAM/SMATH) to compare with the data?

A. They have different mean field potentials available.

C. FYI: other 3 GeV paper used UrQMD cascade+mean field. For tritons, they are not produced in the model. So We used proton v2 as an input in JAM model and implemented coalescence in afterburner.

Slide 25:

Q. Can you update this cartoon with better resolution version?

A. Yes, we can.