STAR Flow, Chirality and Vorticity PWG

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

Dear Jiangyong and Chunjian
Thank you for pointing this out. I would wait for a confirmation from 
Chunjian 
that we can take these two plots in two different presentations as 
apple-to-apple 
comparison, which is just given by the centrality bin width effect or not. 

While an additional direct comparison in the lower-right 2x2 plots on the 
same 
page 7 from Chunjian’s slide for the last week, "black to black" and "blue to 
blue“ 
comparison between upper and lower panel will tell us what I meant as 
shifting 
effect, that should be seen only in blue relative to black, where black and 
blue 
are almost exactly on top (and aligned) in each of 2x2 panel, where I do not 
see 
the bin width effect, there. 
Best regards, ShinIchi

> On Oct 7, 2021, at 23:36, Jiangyong Jia via Star-fcv-l 
> <star-fcv-l AT lists.bnl.gov> wrote:
> 
> Shinichi,
> 
> This was shown before on Aug 4 on slide 11 (solid circles)
> https://drupal.star.bnl.gov/STAR/system/files/isobar_nuclear_deformation_0804_bulkcorr_czhang.pdf
> 
> which you can compare with top-left panel of slide 7 from last week
> https://drupal.star.bnl.gov/STAR/system/files/isobar_nuclear_deformation_0929_Collmeeting_czhang_v3.pdf
> 
> you can see the difference without needing to plot them directly.
> 
> Jiangyong
> 
> On 10/7/21 10:28 AM, ShinIchi Esumi via Star-fcv-l wrote:
>> Dear Chunjian
>> If you have the comparison between the two ratios "ratio of average" and 
>> "averaged ratio" in both wide and small steps of the centrality bin, that 
>> you 
>> have not shown us yet, right? On the other hand, the shifting effect 
>> should 
>> always be there, where we are comparing v2 at different multiplicity for a 
>> given 
>> centrality in case of centrality dependent plot as I mentioned in my 
>> previous 
>> E-mail, that I hope you have understood. So if you could just re-plot what 
>> I’ve 
>> mentioned in "PS" of my previous E-mail, I would guess you could judge 
>> yourself what the more dominant effect is. 
>> Best regards, ShinIchi
>> 
>>> On Oct 7, 2021, at 22:17, Jiangyong Jia via Star-fcv-l 
>>> <star-fcv-l AT lists.bnl.gov> wrote:
>>> 
>>> Hi, Shinichi,
>>> 
>>> I want to chime in and clarify this point
>>> 
>>>> So I just wanted to say it is reasonable to see your minimum at about 
>>>> Nth_corr~220 
>>>> to be systematically higher at about ~1.01 than the other minimum of 
>>>> about ~1.00 at 
>>>> centrality 5-20%. Maybe this is what you meant by saying "the ratio of 
>>>> average and 
>>>> averaged ratio are different" or "the centrality bin width effect”, 
>>>> which sounds different 
>>>> to me. But anyway, I think we understood, which is more like “a shifted 
>>>> ratio" etc. I think 
>>>> it was indeed a good decision for you to show the ratio as a function 
>>>> multiplicity, which 
>>>> is expected to be different from the one as a function of centrality 
>>>> anyway. Thanks 
>>>> again for the hard works and interesting results. 
>>>> Best regards, ShinIchi
>>> There are two effects
>>> 
>>> 1)  We have found even if you bin events in centrality, as long as it is
>>> very fine bins in centrality, you will see the ratio is at 1.01.
>>> 
>>> This is really because centrality bin width effect. <v2R/V2Zr>
>>> !=<v2R>/<V2Zr>. Because the latter ratio, the <Nch> for <v2R>
>>> and <v2Z> are different in the central region. 
>>> 
>>> 2) second effect is that the peak of v2 ratio is around Nch~80 (the peak
>>> is very broad and shallow), while the peak of v2 ratio obtained for wide
>>> centrality bin as in CME paper would be around 40-50% corresponding to
>>> Nch~60. This difference in this case is actually due to the fact that
>>> <v2R/V2Zr> at the same Nch does not corresponds to the ratio at the same
>>> centrality. i.e. <v2R/V2Zr>_Nch !=<v2R/V2Zr>_cent. In fact, if we bin
>>> events with narrow centrality, we can recover the same peak location.
>>> 
>>> Jiangyong
>>> 
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