STAR Flow, Chirality and Vorticity PWG

[egroker <egroker1 AT gmail.com>]

Dear Conveners,

Thank you for your feedback
I implemented comments from Jiangyong, please have a look at new version: https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V3.pdf

I guess, in future I'll try to use EP method as main option for KFParticle calculations, and I'll be back to PWG with KFParticle with helices comparison ASAP.

Thank you,
Egor Alpatov

On Mon, Oct 12, 2020 at 7:10 PM ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp> wrote:

Dear Egor
Your comment about the following is indeed interesting and it might mean the
invariant mass method is not really adequate for the KF particle method, since
the relative BG contribution is not really determined by the “random” combinatorial
contribution. This is also seen just by looking at the Minv distribution, which does
not look like the single gaussian from the detector resolution + random combinatorial
BG, which should have a smooth function with Minv, which is most likely not the
case and might even have a weak peak at the lambda mass, because of the way
how it is done in KF. I hope you will come back to the PWG with more detailed
studies on these points. Thank you very much.
Best regards, ShinIchi

“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."

> On Oct 12, 2020, at 1:50, egroker <egroker1 AT gmail.com> wrote:
>
> Dear Conveners,
>
> I've already written about implementation of Shinichi's comments, but I guess it could be lost in this dialogue.
> Please have a look at my proceeding and comment it if necessary: https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V2_0.pdf
>
> Thank you,
> Egor Alpatov 
>
> On Thu, Oct 8, 2020 at 11:30 AM egroker <egroker1 AT gmail.com> wrote:
> 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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