STAR Flow, Chirality and Vorticity PWG

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

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
>