STAR Flow, Chirality and Vorticity PWG

[egroker <egroker1 AT gmail.com>]

Dear Shinichi,

Thank you for comments, I implemented almost all of them. Here is the link:
https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V2_0.pdf

And some comments and answers:

>L20-23 connection from flow to vorticity
I just realised, that in text I didn't mention vorticity yet, and talking about global polarization bit later, so i removed it from here. Now the logic is "flow understanding->initial conditions->global polarization, dependent on these conditions too"
Hope it fits well....

>L57 optical fibers in BBC

From documentations we have much more optical fibers in EPD, but they also are used in BBC

>Fig.3 Fit of <sin> vs Minv: background polarization

The effect from making parameter free is ~ 2% both for Lambdas and Xi, but I didn't include it yet in systematics. I'll try to say why.
When we were doing this for the traditional helix method, we had a big background with some proton-pions pairs with random proton's phi,

BUT in KFParticle these particles are also fitted into the decay point, which, as we see from the fact that their invariant mass doesn't correspond with Lambda, doesn't even exist.

While for particles of interest in mass window (Lambda and Xi) we probably get something like "true" angle between particles from these fit, it also creates "false" angles for tracks in the background. 
This leads to the possibility of some "big background polarization", which doesn't really exist

So for now my opinion is that we SHOULD assume background polarization to zero, because these are our expectations from physics.
I could make picture wider, so there'll be more observable big fluctuations around zero for Lambdas, but I'm afraid in this case this picture will become just a mess, cause I need to keep the same y-axis range for Xi and Lambda <sin>.

Anyway, I remember my promise to show differences between KFParticle and Helices methods, and I will do it ASAP and look at this point more precisely.

Thanks,
Egor Alpatov

On Thu, Oct 8, 2020 at 6:31 AM ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear Egor and all
I send you my comments on your nice proceeding, which would need to be submitted almost
simultaneously just after your talk during the conference, this is almost impossible for us to
review both your talk and proceedings at the same time, it is not your fault though… I would
sign off with the following comments implemented.
Best regards, ShinIchi

L11-12: It would be better to say why this is important.
L20-23: It would be better to have some connection from flow to vorticity like directed flow and global polarization etc, between the two sentences.
L25-26: You are missing a word after polarized or remove "by this..."
L37: ... differential measurements like pT, rapidity and azimuthal dependences etc?
L38: , and this could be achieved by additional measurements using ...
L57: I thought optical fibers are used only for EPD, not for BBC, maybe I’m wrong, please make sure.
Eq.4: I know people uses tan^-1, but I would choose to write atan2(Qy, Qx)...
L66: TPC B-field (parallel to Z) would limit the pT, not the total momemtum...
L67: The number of hits per track automatically limits the eta acceptance, but you can do the additional cut on eta, so you can select eta, so it sounds odd to say "should".
L89-90 and Eq.6 : superscript is changing "Bg" and "bckg", I would prefer just "bg". "sgn" can be spelled out as "signal".
Fig.3: Are there better choice of figures? The BG region could have even a larger polarization than the signal region especially for Lambda, so the zero polarization assumption would not hold here. I hope your systematic error would include at least free constant parameter fit for the BG polarization, right?
L102 and 107: A weak centrality dependence could possibly be seen, "observed" might even be too strong, or?
L103: would require
L109: Non-zero sigal with ~2sigma ...

> On Oct 7, 2020, at 21:28, Takafumi Niida <niida AT bnl.gov> wrote:
>
> Dear Jiangyong and all,
>
> Now this proceedings is under FCV PWG review.
> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/global-hyperon-polarization-auau-collisions-√snn-27-gev-star-experiment
>
> I checked the conference page and it seems they request to submit proceedings just after the conference (by October 11):
> https://urldefense.com/v3/__https://indico.particle.mephi.ru/event/35/page/46-conference-proceedings__;!!P4SdNyxKAPE!S09R-z82LnJa6M8RC0xP_jWUpFOKPaFoFtFDx9H02oegCbnRY9y3eWiRTqsZQLP8edefjrzZ$
>
> Best regards,
> Takafumi
>
>
>> On Oct 7, 2020, at 9:07 PM, Jiangyong Jia <jiangyong.jia AT stonybrook.edu> wrote:
>>
>> I confused this as a talk and pressed button by accident, and I did not
>> understand why they need to post proceedings now.
>>
>> Can we restart the process?
>>
>> Jiangyong
>>
>> On 10/7/20 4:31 AM, Takafumi Niida wrote:
>>> Dear FCV and CF conveners,
>>>
>>> I notice that participants for ICPPA (Egor, Eugenia, Petr) posted their proceedings while we went through the talk slides (except Petr). One of them (Egor’s one in FCV) came to star-talks but I didn’t see you made any comment on it. Just in case you overlooked or mixed with the talk slides, I just wanted to ask you to take a look and make comments. It’s also possible that I missed the discussion. If so could you send me the link to the email thread?
>>>
>>> Egor’s proceedings:
>>> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/global-hyperon-polarization-auau-collisions-√snn-27-gev-star-experiment
>>>
>>> Eugenia’s proceedings:
>>> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/pion-femtoscopy-pau-and-dau-collisions-sqrtsnn-200-gev-star-experiment-1
>>>
>>> Petr’s proceedings: Not yet posted
>>>
>>> Thank you.
>>>
>>> Best regards,
>>> Takafumi
>>>
>>
>

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