STAR Flow, Chirality and Vorticity PWG

[Takafumi Niida <niida AT bnl.gov>]

Dear Isaac,

For curiosity, I had a quick look at the data.

https://www.star.bnl.gov/protected/bulkcorr/taknn/2023/20230320_ESE.pdf

As Sergei and Gang already mentioned, probably nothing wrong with your plots. Just a matter of the sensitivity. For my test, I used TPC q2 from eta>0 and looked at v2 at backward rapidity, then the variation in v2 is <30%. If you use EPD q2, the variation would be smaller.

Best regards,

Takafumi

On Mar 18, 2023, at 3:23, Sergei Voloshin via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi Rosi, all,

- a side note -- to have in two weeks the results ready to show in public sounds a bit "overoptimistic"...

- It could be good to present the goal of this analysis - to study/measure what? It would help to understand how "efficient" ESE might be for that.

- the plots in Issac's presentation might be all right. Have you tried to estimate what to expect? Note that the ESE allows to vary v2 for about 20-50% (very roughly, depends on multiplicity, likely even less in isobar collisions). The contribution to q2 from v2 might be rather small; v2^2 \approx (q2^2 -1)/(mult-1) ).

- I would suggest to plot v2 vs q2. It is partially reflected in correlations observed in the resolution (slide 11) - but I am afraid the latter is "dominated" by the multiplicity variations.

- Judging from the EPD Psi2 resolution plot in slide 3, I would not be very optimistic for a significant variation in v2 vs q2, but it is worth to make the plot

- I would not "jump" to the method suggested by Gang. This one was developed for a very specific case (suppression of the background to the gamma correlator), and even there, the evaluation of corresponding "systematics" is far from fully understood.

regards,

Sergei   

On Fri, Mar 17, 2023 at 11:27 AM Rosi Reed via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi Zhenyu,

I'm a little confused, the weights that Isaac is using are the tile-by-tile EPD weights.  Would one use the weights that are calculated for flattening, etc, the EP as well?

The idea of this analysis is going into a poster and talk for the Hard Probes conference in 2 weeks, so it would be helpful if Isaac could get comments on a time scale earlier than a week.  At the very least, confirming the analysis procedures.  Right now he doesn't see a correlation in the TPC either - perhaps this is the weighting issue you mention.

Cheers,

Rosi

On Thu, Mar 16, 2023 at 10:43 PM zhchen via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi Isaac,

I would encourage you to present in next PWG meeting to have more
detailed discussion.
Based on my experience on a few event shape engineering analyses, the
definition of q2 is the magnitude of Q2  = Sum(w*exp(i2phi))/Sum(w). So
the denominator should include not only the multiplicity M but also the
other EPD weights.
Hope this could be helpful.

Cheers,
Zhenyu


在 2023-03-16 04:42，Mooney, Isaac via Star-fcv-l 写道：
> Hi FCV members,
>
> I’m a member of the HardProbes PWG, and I’ve been investigating some
> interesting behavior with q vectors as part of my analysis. I was
> splitting events into q2 classes, before seeing the plot I’m showing
> on slide 4 of the attached pdf, which raised the question of whether
> this is actually possible to do meaningfully.
> I was hoping to show the slides at the meeting today, but since it was
> canceled, I’m sending them here. If you have a minute, please take a
> look and let me know if you have any thoughts. To me the behavior is
> non-intuitive enough that it’s possible there’s a solution that is
> very obvious to an expert eye. And please let me know if anything in
> the slides is not clear and I would be happy to clarify it.
>
> I really appreciate any time you have to think about this!
> Best,
> Isaac
>
>
> _______________________________________________
> Star-fcv-l mailing list
> Star-fcv-l AT lists.bnl.gov
> https://lists.bnl.gov/mailman/listinfo/star-fcv-l
_______________________________________________
Star-fcv-l mailing list
Star-fcv-l AT lists.bnl.gov
https://lists.bnl.gov/mailman/listinfo/star-fcv-l

--

Rosi Reed
RHIC/AGS UEC member
Associate Professor, Physics Department
Lehigh University
(610)758-3907
16 Memorial Drive East Office 406
Bethlehem, PA 18015
she/her/hers

_______________________________________________
Star-fcv-l mailing list
Star-fcv-l AT lists.bnl.gov
https://lists.bnl.gov/mailman/listinfo/star-fcv-l

--

======================================
 Sergei A. Voloshin
 Professor of Physics,  Wayne State University,
 666 W. Hancock,  Detroit,  Michigan,  48201
 e-mail: sergei.voloshin AT wayne.edu
 Phone: 1-313-577-1630;  Fax: 1-313-577-0711     
======================================

_______________________________________________
Star-fcv-l mailing list
Star-fcv-l AT lists.bnl.gov
https://lists.bnl.gov/mailman/listinfo/star-fcv-l