STAR Flow, Chirality and Vorticity PWG

["Huan Zhong Huang" <huang AT physics.ucla.edu>]

Hoajie,
  You corrected for some of the significant differences (luminosity and Vz) 
between the isobar systems. At the end how you determine the final accuracy 
of our systematic correction and how you compare your accuracy with the 
sensitivity to the ratios. If there are indeed a slight shift in x-y position 
of the beam between isobar systems, how your procedure will take care of this 
slight shift. 
  Please note neither Yu nor I claim the multiplicity shift is reliable or 
real. We just wish to point out that the ratios used in the physics analysis 
is sensitive to small difference and we need to demonstrate that we have 
reached the accuracy that we need to adequately pursue the physics topic. 
  Thanks.
  Huan


-----Original Message-----
From: haojiexu <haojiexu AT rcf.rhic.bnl.gov> 
Sent: Wednesday, April 13, 2022 5:41 PM
To: Huan Zhong Huang <huang AT physics.ucla.edu>
Cc: 'STAR Flow, Chirality and Vorticity PWG' <star-fcv-l AT lists.bnl.gov>; 
'Chunjian Zhang' <chun-jian.zhang AT stonybrook.edu>
Subject: Re: [Star-fcv-l] STAR presentation by Haojie Xu for Quark Matter 
2022 submitted for review

Hi Huan,

Thank you for your comments and interest in my QM talk. And also thank Yu for 
the testing on multiplicity shift, the effect of one bin offset is large but 
I don’t think this shift is reliable.

The multiplicity ratios shown in my QM slides are not the raw multiplicity 
distributions. As it was done in the general centrality definition procedure, 
we have corrected the luminosity dependent and the multiplicity distributions 
in different vz bins are corrected to vz=0. I think the effect you mentioned 
has been taken care of by the procedures. 
More details of the procedure can be found in my presentation given in the 
centrality definition meeting:
https://drupal.star.bnl.gov/STAR/system/files/Centrality20220301.pdf

Yes, the neutron skin effect can also be obvious at peripheral collisions. 
One of the observables is the net charge ratios I have shown in my QM 
presentation.

with best regards,
Haojie

On 2022-04-12 03:19, Huan Zhong Huang wrote:
> Hi Haojie et al,
>   This is an interesting approach. I am concerned whether you have 
> done the systematic checks to demonstrate the sensitivity of potential 
> systematic bias to the physics conclusion. Yu Hu helped to plot the 
> multiplicity ratio of Ru+Ru/Zr+Zr if the multiplicity of the Zr+Zr 
> collisions is systematically offset by a few tracks. When the Zr 
> multiplicity is shifted by one track out of 300-400 tracks, the ratio 
> changes very significantly. Therefore, it is critical that we show 
> that there is no systematic bias between two isobar collisions even at 
> one particle level.
>   Because of the isobar charge difference, I tried to ask CAD what the 
> possible magnitude of beam difference (position and collision axis).
> Bill Christie suggested that we should be able to get the data from 
> reconstructed vertex distributions as a function of Z. Gene Van Buren 
> has some data on this. He indicated that the beam position between Ru 
> and Zr could be shifted by 40-50 microns. We may need to examine this 
> shift with the full isobar data. In order to examine if this magnitude 
> of beam shift will cause any systematic bias in the measured 
> multiplicity, we may need to use GEANT simulations of the Ru+Ru 
> collisions and shift the beam position to measure potential change in 
> the TPC multiplicity. That would ensure that we have a good control of 
> the systematics. There may be other approaches to use experimental 
> data to examine the potential shift due to beam variations. But I do 
> not know how well we can control the systematics with the experimental 
> approach.
>   If this potential systematic shift is real, we may have to revisit 
> the model used for centrality definition as well.
>   Naively I would expect that the peripheral collisions would be more 
> sensitive to the shape and distribution of the neutron skin.
>   In any case, this is an interesting topic. It would be good if you 
> help evaluate these sensitivity issues. I am sorry that it took me 
> long to catch up with many interesting QM talks and did not comment 
> sooner.
>   Thanks. Regards,
>   Huan
> 
> -----Original Message-----
> From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> On Behalf Of 
> haojiexu via Star-fcv-l
> Sent: Wednesday, March 30, 2022 10:39 AM
> To: Chunjian Zhang <chun-jian.zhang AT stonybrook.edu>
> Cc: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
> Subject: Re: [Star-fcv-l] STAR presentation by Haojie Xu for Quark 
> Matter 2022 submitted for review
> 
> Dear Chujian, Rongrong, and all,
> 
> Slide 12 has been updated with chunjian's new plot. Comments from 
> google doc are also implemented. Here is the link to the updated 
> slides
> 
> https://drupal.star.bnl.gov/STAR/system/files/QM2022_HaojieXu_v11.pdf
> 
> with best regards,
> Haojie
> 
> 
> On 2022-03-30 09:52, Chunjian Zhang wrote:
>> Dear Haojie,
>> 
>> Hello. It’s a very nice result from hydro and I am looking forward to 
>> your nice draft. Thank you~
>> 
>> best regards
>> Chunjian
>> 
>>> On Mar 29, 2022, at 8:46 PM, haojiexu <haojiexu AT rcf.rhic.bnl.gov>
>>> wrote:
>>> 
>>> Dear Chunjian,
>>> 
>>> Thank you for considering my suggestion. Actually, our hydrodynamics 
>>> give the same conclusion that the two system have the same nonlinear 
>>> coefficients within error, while the approximation can bias this 
>>> conclusion. It is good to hear that the data show the same trend.
>>> It is interesting that the magnitude of this bias can be 
>>> quantitively described by our hydrodynamic simulaitons, this may 
>>> indicate the non-flow contributions are largely canceled in the 
>>> ratios.  Attached please find plot from our recent work that we plan 
>>> to submit to arXiv in the next few days.
>>> 
>>> with best regards,
>>> Haojie
>>> 
>>> 
>>> 
>>> On 2022-03-30 07:50, Chunjian Zhang wrote:
>>>> Dear Haojie,
>>>> Hello. Very nice and comprehensive slides to me.
>>>> Thank you for your nice suggestions. Now we use the exact 
>>>> ac2{3}/<v_2^4> ratio between Ru+Ru and Zr+Zr collisions as the 
>>>> equations.
>>>> Please find the new plot in
>>>> https://drupal.star.bnl.gov/STAR/system/files/ac23_STAR_0329.pdf  
>>>> It will be helpful if you could use this new plot to replace the 
>>>> old version in the slide 12. And also change the third bullet point 
>>>> to “Non-linear coefficents are ideally identical in the final-state””.
>>>> Thank you.
>>>> The nonflow would be mostly canceled and then will not affect the 
>>>> double ratios in the lower panel especially from midcentral to 
>>>> central collisions.  If it still has residual nonflow, it may only 
>>>> affect peripheral region a little bit. The model study here also 
>>>> helps us to clarify this.  Even so, the futher relevant nonflow 
>>>> understanding is ongoing in our to do list.
>>>> best regards
>>>> chunjian
>>>>> On Mar 29, 2022, at 1:07 AM, haojiexu <haojiexu AT rcf.rhic.bnl.gov> 
>>>>> wrote Hi Chunjian, and all Your nice suggestions are implemented, 
>>>>> here is the updated slides
>>>> https://drupal.star.bnl.gov/STAR/system/files/QM2022_HaojieXu_v10.p
>>>> d
>>>> f
>>>>> I am still worried about the message from lower panel of ac3 plot.
>>>>> Besides the non-flow effect, as I have already mentioned, the 
>>>>> ac2{3}/v_2{2}^{4} is not exactly the non-linear coefficient.  As 
>>>>> it was just an approximation, I suggest not to extract any 
>>>>> nonlinear coefficient at this moment. Or can you directly compare 
>>>>> ac2{3} to <v_2^{4}> instead of v_2{2}^{4}?
>>>>> with best regards,
>>>>> Haojie
>>>>> On 2022-03-29 04:56, Chunjian Zhang wrote:
>>>>> Dear Haojie,
>>>>> Hello. Very nice and comprehensive slides. Please find some 
>>>>> comments
>>>>> below:
>>>>> 1) S3:
>>>>> —>  v2-> v_{2}
>>>>> —> I guess you would like to use the new Ntrk ratio plot from the 
>>>>> nice isobar publication.
>>>>> 2) S9: It would be helpful if you could add one more reference:
>>>>> J.Jia
>>>>> and C. Zhang, arXiv:2111.15559
>>>>> 4) S12:
>>>>> —> above formula, n=2, just label ac_2{3}….
>>>>> —> I would be helpful you could add a punchline as other slides at
>>>>> below: “Experimental test on non-linear coupling coefficient”.
>>>>> Thank you for your suggestions for the plots. The double ratio is 
>>>>> the money plot calculated from above panels. Then the audiences 
>>>>> would see how is the difference directly. Also, ampt calculation 
>>>>> could reproduce the data. The detailed nonflow studies for 
>>>>> understanding any flow observables are extramly complicated and 
>>>>> there are no any conclusive answers yet. let’s not worry about it.
>>>>> best regards
>>>>> Chunjian
>>>>> On Mar 28, 2022, at 11:22 AM, haojiexu via Star-fcv-l 
>>>>> <star-fcv-l AT lists.bnl.gov> wrote:
>>>>> Dear chunjian, and all
>>>>> The slides have been updated with suggestions from the last FCV 
>>>>> meeting and Collaboration meeting. I also made a few minor changes.
>>>>> Your comments are welcome. Here is the link to my slides 
>>>>> https://drupal.star.bnl.gov/STAR/system/files/QM2022_HaojieXu_v9.p
>>>>> d f I have a suggestion on ac2{3} plot in slide 12. I suggest do 
>>>>> not show the lower panel and the value of the non-linear 
>>>>> coefficient ratio, because the ac2{3}/v_2{2}^{4} is not exactly 
>>>>> the non-linear coefficient, and ac2{3} is also sensitive to 
>>>>> non-flow effect.
>>>>> with best regards,
>>>>> Haojie
>>>>> On 2022-03-08 23:55, webmaster--- via Star-fcv-l wrote:
>>>>> Dear star-fcv-l AT lists.bnl.gov members, Haojie Xu
>>>>> (haojiexu AT zjhu.edu.cn) has submitted a material for a review, 
>>>>> please have a look:
>>>>> https://drupal.star.bnl.gov/STAR/node/58778
>>>>> ---
>>>>> If you have any problems with the review process, please contact 
>>>>> webmaster AT www.star.bnl.gov 
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