STAR Correlations and Fluctuations PWG

[Takafumi Niida <niida AT bnl.gov>]

Date: 10/22/2021

Participants: Yu Zhang, Daniel Cebra, Xin Dong, Xiaofeng Luo, Sooraj Radhakrishnan, Daniel Brandenburg, Daniel Cebra, Hanna Zbroszczyk, Jiangyong Jia, Maria Zurek, Matt Posik, Md. Nasim, Prithwish Tribedy, Qinghua Xu, Raghav Elayavalli, Hanseul Oh, ShinIchi Esumi, Helen Caines, Rongrong Ma, Takafumi Niida

Title: High Order Cumulants and Correlation Functions of Proton Multiplicity Distributions in \sqrt{s_{NN}} = 3 GeV Au+Au Collisions

PAs: Yu Zhang, Daniel Cebra, Xin Dong, Samuel Heppelmann, Ho San Ko, Xiaofeng Luo, Toshihiro Nonaka, Sooraj Radhakrishnan, Nu Xu

Target journal: PRC

Proposal page: https://drupal.star.bnl.gov/STAR/blog/sheppel/protonhighermoments3gev

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

The PWGC panel previewed a paper from CF PWG. This was done before with the short paper but re-previewed because of new plots added and some modification. The panel think that the results are mature having all the details of analysis. The target journal is appropriate. The following points were discussed.

Fig. 9 and 19

Q. In the end, VF is applied to the data. UrQMD is not corrected for VF?  VF is large and mode-dependent. How could it affect physics conclusion, any effect on root-S dependence?

A. VF correction is not applied to UrQMD. VF is small at higher energies. Also, results with VF correction and results with CBWC are consistent at higher energy. When comparing to other energies, most central data is shown where VF effect is very small.

Q. Since we present VF-uncorrected data, can theorists apply their new VF correction if developed and possibly get different physics conclusion?

A. Current model used in this study is already typical model. PAs wouldn’t expect huge difference. Also at central bin the effect is ~5%.

Q. In Fig. 9, the result “w/o VF corr” is corrected for CBWC? 

A. Yes.

Q. “b<3 fm” can be considered as true value?

A. Yes.

C. It would be nice to add results of CBWC with npart here.

Q. VF is large in mid central collisions according to slide 13. The trend can be seen when comparing results with/without VFC(Galuber), but not for VFC(UrQMD). Any comment?

A. Probably because of poor resolution at peripheral collisions.

Q. How is the pile-up correction technically done?

A. If we know single-collision multiplicity distribution and pile-up events are described by superposition of them, the cumulants can be recursively corrected from low multiplicity by subtracting the pile-up contribution.