STAR Flow, Chirality and Vorticity PWG

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

Dear Haojie and ShinIchi,
  Thanks for the update and sorry for the late response. It is very typical 
nowadays that I lag behind in my email responses.
  On a gross scale, I do not have any problem if you claim that there is no 
effect related to vertex and/or efficiency differences. But when you focus on 
the ratio at the very tail region, we know that the sensitivity is very much 
enhanced. So I have not seen any quantitative estimate that demonstrated that 
there is nothing to worry about.
  When you examine the multiplicity and the vertex positions to see if there 
is any correlations, you did it as a function of run number. I am afraid that 
this approach may not be a sensitive way. As you may know the vertex position 
averaged over a run contains too many effects including the z vertex and the 
slope parameters which may be run dependent. You may be better off to focus 
on data within one run. I understand that you have already done the Vz 
dependent corrections. So you may ask the question whether you correctly 
attributed the physical reason for the Vz correction and whether the 
correction method (for the turning point, instead of the falling shape for 
example) is well justified.
  When I suggested you to carry out quantitative systematic estimate, it 
probably does not make sense to you. Let me try to elaborate a little. Since 
you focus on the ratio of multiplicity in the tail region, you may check how 
the ratio changes with possible multiplicity shift (more detailed and finer 
steps than Yu did). Then if you decide that in order to constrain nuclear 
shape parameters well using the ratios in the tail region, you may decide our 
goal of systematic error allowed. That would be our quantitative goal for 
controlling the systematics for this physics measurement. 
  Once you know the goal that you need to achieve, you may be able to examine 
if your Vz/Vx/Vy studies are compatible with achieving the goal. We know that 
the average multiplicity between Ru+Ru and Zr+Zr differ by a few counts while 
the average Vx and Vy are slightly different. I wondered that among these two 
refmult difference how much should be attributed to true shape difference and 
how much to run condition difference. What makes you so confident that there 
is no effect from vertex difference at the accuracy level that we need to 
achieve. If we trust the simulation package, we may have to simulate the same 
collisions with a slight shift in vertex positions in order to guage the 
sensitivity.
  In any case, thanks for the hard work. 
  Regards,
  Huan

-----Original Message-----
From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> On Behalf Of ShinIchi 
Esumi via Star-fcv-l
Sent: Thursday, April 21, 2022 8:58 PM
To: 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 Haojie
Thanks for the plots. I have one question. 
Is the second page for the entire run and event for both RuRu and ZrZr? 
Could you plot the 2nd page correlation just for the two run ranges for each 
of 2 species, where you draw 2 black lines (run ranges) in each panel of the 
1st page, and plot one range for red and another range for blue points? 
Could you also plot each point event-by-event, not run-by-run for these two 
run ranges. 
Best regards, ShinIchi

> On Apr 22, 2022, at 10:33, haojiexu <haojiexu AT rcf.rhic.bnl.gov> wrote:
> 
> Dear ShinIchi, Huan, and all,
> 
> Under Jiangyong's suggestion, I have plotted the run-by-run vertex 
> distributions in both Ru+Ru and Zr+Zr collisions, attached please find the 
> plots. The vertex variations in each system are larger than the average 
> difference between the two systems. I also plot the <RefMult> vs <vx>, <vy> 
> and <vr> in each collision system. There is no evidence of efficiency 
> difference over vx, vy variations on this level.
> 
> with best regards,
> Haojie
> 
> On 2022-04-21 20:49, ShinIchi Esumi via Star-fcv-l wrote:
>> Dear Huan and all
>> There were some interesting discussions about this in the PWG meeting 
>> yesterday, the results presented by Haojie in the meeting were not 
>> enough to fully answer your question (you can see his slide in the 
>> usual PWG agenda page at :
>> https://drupal.star.bnl.gov/STAR/blog/jjiastar/bulkcorr). One 
>> difficulty is the vertex resolution changes with centrality (track 
>> multiplicity in the tpc),  but there were few more suggestions made 
>> during the meeting, so let’s see his future updates. Do we just worry 
>> about the actual vertex position dependence of the tpc efficiency?, 
>> which is basically the homework for Haojie to see the vertex position 
>> (3D xyz vertex) dependence of efficiency (effectively number of 
>> reconstructed track for a given acceptance), Or do we also need to 
>> worry about beam tuning/focusing differences, for example, beam 
>> crossing angle difference etc between the species?
>> One thing I forgot to ask yesterday was about the simulation test, 
>> where we used say our accuracy of tracking efficiency is of the order 
>> of 5% for the systematic error evaluation in the absolute yield 
>> measurements, which is clearly not enough for these studies, so the 
>> most of the people seem to be given up in this direction, but I 
>> remember there were some task force formed sometime ago, to revisit 
>> our accuracy of 5% on the absolute efficiency in the tpc, and to see 
>> if we can improve this or not. We need to see if there is any 
>> progress in this direction or not, too… Best regards, ShinIchi
>>> On Apr 15, 2022, at 11:42, Huan Zhong Huang <huang AT physics.ucla.edu> 
>>> wrote:
>>> Hi ShinIchi and Haojie,
>>> Thanks for the discussion. To pursue the physics topic, we need to 
>>> demonstrate that we have done the systematic study to the accuracy of 
>>> much better than 1/(300-400) in multiplicity measurement. We may have 
>>> done lots of systematic studies, but I am not aware one which showed the 
>>> accuracy matched what is needed for this physics topic. It will be useful 
>>> to keep this requirement in mind when you consider more studies. It would 
>>> certainly be very useful to have a full geant simulation of Ru collisions 
>>> with realistic beam profile and with the correct magnitude of position 
>>> shifts to see any effect.
>>> Haojie: if you think that your previous results have the accuracy needed, 
>>> please summarize your results/arguments in a few slides to circulate. In 
>>> particular, we will be interested in why you think that you have the 
>>> quantitative accuracy of 1/(300-400).
>>> Thanks. Regards,
>>> Huan
>>> -----Original Message-----
>>> From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> On Behalf Of 
>>> ShinIchi Esumi via Star-fcv-l
>>> Sent: Wednesday, April 13, 2022 7:50 PM
>>> To: 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 Haojie Thank you for the 
>>> confirmation. The question is how accurately we do know the relative 
>>> efficiency difference between species, compared to the observed level of 
>>> multiplicity difference of ~1/(a few 100). TPC condition itself is 
>>> unchanged as we filled two beams alternatively, but the beam 
>>> optics/position seems to be different. The effect coming from less than 
>>> mm difference of beam using the meter size detector would be small, but 
>>> we just need to make sure the effect is at lease much smaller than ~1/(a 
>>> few 100) in the realistic experimental condition.
>>> Best regards, ShinIchi
>>>> On Apr 14, 2022, at 11:35, haojiexu <haojiexu AT rcf.rhic.bnl.gov> wrote:
>>>> Dear ShinIchi,
>>>> The efficiency corrections are not implemented yet. As we have 
>>>> discussed during my presentation, we plan to use the same 
>>>> efficiency for two isobar systems, as the accuracy may not be good 
>>>> enough to do it separately.
>>>> with best regards,
>>>> Haojie
>>>> On 2022-04-14 09:29, ShinIchi Esumi via Star-fcv-l wrote:
>>>>> Dear Haojie and all
>>>>> I think Huan has a point, if the tracking efficiency is really 
>>>>> different between the two species caused by the small beam shift 
>>>>> (or any beam related systematic difference), the beam luminosity 
>>>>> and/or zvertex corrections for the refmult would not correct such 
>>>>> difference, since
>>>>> “97 vs 98” difference remain unchanged after the corrections and 
>>>>> this difference of “1 out of 500” that we believe that it is 
>>>>> coming from the nuclear structure, but I‘m not sure we have ruled 
>>>>> out any small fraction of “1” that might be coming from the beam 
>>>>> systematics or not.
>>>>> Do we correct for the tracking efficiency (for the refmult) 
>>>>> independently between two species?
>>>>> This might be a question of accuracy of our embedding simulation, 
>>>>> that does use the real data, but how precisely we can reproduce 
>>>>> the beam quality/position difference for the embedded track to be 
>>>>> combined into the real events for each species independently. Or 
>>>>> we might need to test this with full geant simulation with 
>>>>> realistic beam optics/profile, to see if our TPC (with realistic 
>>>>> holes of inactive RDOs etc) is sensitive to this or not. This is 
>>>>> to ask ourselves, if we already know our TPC efficiency (better 
>>>>> than ~1/500) relatively between two species, that is being questioned.
>>>>> Best regards, ShinIchi
>>>>>> 2022/04/14 9:41、haojiexu via Star-fcv-l 
>>>>>> <star-fcv-l AT lists.bnl.gov>
>>>>>> のメール：
>>>>>> 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_v1
>>>>>>> 1.p
>>>>>>> df
>>>>>>> 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
>>>>>>>>>> _v1
>>>>>>>>>> 0.pd
>>>>>>>>>> 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_HaojieX
>>>>>>>>>>> u_v 9.pd 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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