STAR Flow, Chirality and Vorticity PWG

[ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp>]

Dear Chunjian

Thanks for the quick answers. 

In some of your earlier presentations on 16/Jun and 1/Jul, I see somewhat different 

v2 variance definition on p5 and p4, respectively. Is this same as what you show on p6 

from today? I think my question was what happens if you just use only the 2nd term in 

your earlier presentations p5(16/Jun) or p4(1/Jul) or a central moment of the v2{2} just 

like the pT variance. 

For about the closure test, I was wondering about the multi-particle effect/efficiency, 

that can not be described by the product of the single efficiency, although such 

non-linear effects could be small and negligible for this variable… By the way, do you 

know why eta-phi-map affects only in small multiplicity region below RefMult<300 from 

Jiangyong’s presentation on 30/Sep? Sorry if I'm forgetting this discussion at that time. 

Best regards, ShinIchi

2020/10/14 11:23、Chun-Jian Zhang <chun-jian.zhang AT stonybrook.edu>のメール:

Dear Shinlchi,

Hello, Thank you for your kind questions. It’s my honor to answer these in advance. 

1. You do have two variables for pT variance (variance and reduced one), while you 

have only one dynamical variance for v2, which is pre-determined by the difference 

between 2- and 4-particle cumulants, have you tried to use other v2 variance definitions? 

My real question is whether this is the best normalization variable? What happens 

if we define this as same as the one for pT variance? 

We use pT variance as our denominator. I think this is not confused. For the v2 variance part, we already showed that

our definition is the best one to get larger statistics and lower non-flow contributions. Moreover, they are consistent. 

Please find them in https://drupal.star.bnl.gov/STAR/system/files/deformation_STAR_SBU_chunjianzhang%20bulk_0616.pdf

For the reduced variance that I want to request preliminary here, I want to address that the reduced pt variance is an important orientation without self-correlation in the future. 

Actually we are now cautious for requesting high-order skewness and kurtosis part, we are doing additional checks and also need to think more its sensitivity.  

2. You’ve shown the standard and sub-event result comparisons in Fig.6. Although 

one might expect and you also mentioned that this is a better with sub-event especially 

for peripheral, but you have chosen the standard one for the final plots, which might be 

understandable because of the better statical significance. But anyway, I do agree it 

would not matter much for this data, though. 

Yeah. That is due to statistical consideration. Subevent methods play a role in suppressing non-flow contributions in peripheral regions. 

For the final publication, we need to deliberate how to show this and which is best way. (This will be decided later)

3. I would still like to see some closure test starting from some model with detector 

filters including acceptance and efficiency, which I hope you could show us sometime 

in the future before your final publication. 

I am a little bit confused about this question. I think jiangyong already showed this in a right way in the last bulk-corrr. 

Please find the slides in https://drupal.star.bnl.gov/STAR/system/files/JiangyongJia_fcv_093020.pdf 

I also did some naive closure test in https://drupal.star.bnl.gov/STAR/system/files/deformation_STAR_SBU_chunjianzhang%20bulk_0701_bulkcorr.pdf

But if you have additional good idea, please let us know. 

4. You labeled “two centrality definition”, however I would think this is done with 

one centrality definition but presented in two different ways: Nch and centrality. 

I would also like to see if you could plot as a function of ZDC energy, for example, 

where we trigger on the ultra central events, or "refMult vs BBC” centrality comparison. 

Yes. You are right. That’s the mis-labeled sentence.  The correct way is centrality in two different way: Nch and Centrality percentage. 

We would not like to squeeze the central region. That’s why I request them together. 

Yeah. That maybe a good idea. Let me rethink about this. But I need to say, centrality definition does’t change the signal and signal is 

also doesn’t depend on the binning style( refmult binning/ Nch binning). 

I hope my naive understanding for your questions is correct and also answer parts of them. 

Best regards,

Chunjian 

On Oct 13, 2020, at 9:38 PM, ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp> wrote:

Dear Chunjian

Very nice results!

In order for you to think about some possible answers in advance, I would like to send 

a few more questions for the meeting tomorrow (tonight for me). 

1. You do have two variables for pT variance (variance and reduced one), while you 

have only one dynamical variance for v2, which is pre-determined by the difference 

between 2- and 4-particle cumulants, have you tried to use other v2 variance definitions? 

My real question is whether this is the best normalization variable? What happens 

if we define this as same as the one for pT variance? 

2. You’ve shown the standard and sub-event result comparisons in Fig.6. Although 

one might expect and you also mentioned that this is a better with sub-event especially 

for peripheral, but you have chosen the standard one for the final plots, which might be 

understandable because of the better statical significance. But anyway, I do agree it 

would not matter much for this data, though. 

3. I would still like to see some closure test starting from some model with detector 

filters including acceptance and efficiency, which I hope you could show us sometime 

in the future before your final publication. 

4. You labeled “two centrality definition”, however I would think this is done with 

one centrality definition but presented in two different ways: Nch and centrality. 

I would also like to see if you could plot as a function of ZDC energy, for example, 

where we trigger on the ultra central events, or "refMult vs BBC” centrality comparison. 

Best regards, ShinIchi

2020/10/14 9:30、Chun-Jian Zhang <chun-jian.zhang AT stonybrook.edu>のメール:

Hi Shinlchi,

Please find my slides in https://drupal.star.bnl.gov/STAR/system/files/Request_Preliminary_chunjianZhang_bulkcorr1012.pdf

Best regards,

Chunjian 

On Oct 12, 2020, at 7:21 AM, ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear FCV PWG colleagues
We will have our weekly FCV PWG meeting on coming Wednesday 14/Oct/2020
9:30AM (in BNL) at our usual time and place. So if you have anything to present,
please let us know and please post your slide by Tuesday. We'll use the same
Zoom room link for the meeting, where the meeting ID and password are in our
usual drupal agenda page below.
Best regards, Jiangyong, Prithwish and ShinIchi

https://drupal.star.bnl.gov/STAR/blog/jjiastar/bulkcorr
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