STAR Flow, Chirality and Vorticity PWG

["Tang, Aihong" <aihong AT bnl.gov>]

Hi, Ashik :

This looks like a nice idea to look at observables. I have one comment on your conclusion. My comment should not affect your paper moving forward for PWGC preview but it is a point for future paper discussions.

We see a seemingly positive correlation between v1 splitting and \Delta q and \Delta s. (page 8 of your slides

https://drupal.star.bnl.gov/STAR/system/files/FCVmeeting_Jul072021_ashik.pdf). You attribute those to possible QED and/or QCD driven effect. However, the \Delta q and \Delta s are highly correlated (page 5). In fact, if one examine a group of particles with same \Delta s in the left plot, one can hardly see a change in v1 splitting. The seemingly positive slope could be solely driven by the \Delta s.  Furthermore, the most significance (15\sigma) is obtained by forcing the fitting function goes to zero at \Delta q = 0. This is fine if the only difference in the plotted samples is \Delta q, however, it is not the case here.  The similar comment applies to the right plot too. It is just striking to me that we are reporting a 15 sigma effect, while looking at groups of samples with same \Delta s but different \Delta q, we can hardly see a difference for _any_ groups.  So we have to be careful about that procedure and the significance obtained from it,  IMO it could be misleading.  That said, it is still an intriguing way to look at the splitting though.

Thanks,

Aihong

  

On Jul 15, 2021, at 5:47 PM, ASHIK IKBAL via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear Conveners, all,

I have prepared the replies to the comments I got during my last FCV presentation (July 07, 2021). Please find my responses here: https://drupal.star.bnl.gov/STAR/system/files/Reply_FCV_Jul072021_ashik.pdf

I would request you for approval to go forward with the PWGC review.

Thanks,

Ashik

On Mon, Jul 12, 2021 at 11:59 AM ASHIK IKBAL <ashikhep AT gmail.com> wrote:

Hi Sooraj,

Thanks for your email. Here are my responses:

The v1 for positive as well negative charge is negative at positive rapidity - at least for the sqrt {s_NN} studied here. You can have a look at (at 27 and 54.4 GeV): https://drupal.star.bnl.gov/STAR/system/files/STARprelim_BulkCorr016102019.pdf

It's true that the magnetic field affects the v1 for positive and negative charge. But, one should keep in mind that the real scenario is much more complicated due to transport for beam rapidity and other effects like Coulomb, etc.  In our analysis, the Delta v1 is not calculated by simply subtracting v1 b/w positive and negative particles (except v1(omegabar) - v1(omega)), rather by subtracting v1 b/w combinations of produced particles. The combinations have different charge differences. The Delta v1 slope increases with charge differences at 27 GeV and I think it is consistent with the deflection from the magnetic field.

Now in my slide 39, I showed the pT/nq dependence of 2 combinations having identical quark contents ((charge diff is zero).). This a test for the coalescence inspired sum rule with pT/nq. You can see that the sum rule holds very well at the intermediate pT region to the pT region shown here. However, at very low pT, there is a difference. While in slide 42, I showed the pT/nq dependence where there are non-identical quark combinations (charge diff is non-zero). So, one should not expect the agreement in the region where there was an agreement for the identical quark content case before. In the other words, this is a violation of the sum rule for non-zero charge diff. 

Our conclusion of the Delta v1 slope is based on the rapidity dependent study. It is important to mention that we curved out the same phase space (pT/nq-y) region for every particle in our analysis. In this way, we already have the lower pT/nq cut in our analysis. 

Regarding the mass scaling effect on flow, I would say there is an effect of mass on the flow. This is respected in our measurements. We combine different produced particles in such a way that the combinations have the same mass at the partonic level.

Let me know if you need further clarifications.

Best,

Ashik

On Fri, Jul 9, 2021 at 3:28 PM Sooraj Radhakrishnan <skradhakrishnan AT lbl.gov> wrote:

Hi Ashik,

   These are nice studies and interesting results. Can I ask a couple of questions/clarifications?

Is the sign of the observed Delta v1 consistent with the deflection from a magnetic field? Shouldnt the v1 from the magnetic field be negative for a positive charge at positive rapidity?

I see on your slides 39, 42 that the pT dependences are not trivial. Do you understand these? In 39, there is a difference at low pT, while in 42 its mostly at high pT. So if you have a lower pT cut, would it change your conclusions?

When you add the v1 and select the pT ranges, would any mass scaling effects affect the flow values? At low momenta, there is also mass scaling in addition to quark number scaling

thanks

Sooraj

On Wed, Jul 7, 2021 at 6:16 AM ASHIK IKBAL via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear all,

Please find my slides here:

https://drupal.star.bnl.gov/STAR/system/files/FCVmeeting_Jul072021_ashik.pdf

Thanks,

Ashik

On Wed, Jul 7, 2021 at 4:26 AM Niseem via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi All,

Please find my slides at this link,

https://www.star.bnl.gov/protected/bulkcorr/niseem/pwg_2021/ptpt_model_data_3.pdf

Thanks,
Niseem

On 7/6/21 4:49 AM, knayak via Star-fcv-l wrote:

Dear Conveners,

    I would like to give the paper proposal “Directed flow of identified hadrons in Au+Au collisions at 19.6, 27 

and 54.4 GeV in STAR”. Could you please add my name in the agenda?

Thanks,

With best regards

Kishora

 Original Message 

Sender: ShinIchi Esumi via Star-fcv-l<star-fcv-l AT lists.bnl.gov>

Recipient: Chirality and Vorticity PWG" <star-fcv-l AT lists.bnl.gov>

Date: Monday, Jul 5, 2021 18:52

Subject: [Star-fcv-l] FCV PWG meeting on 7/July/2021 Wed. 9:30AM at BNL

Dear FCV PWG colleagues 

We will have our weekly FCV PWG meeting on this Wednesday morning 7/July/2021 

9:30AM in BNL (NY time zone) at our usual time and place. So if you have anything to 

present, please let us know and please post your slide by Tuesday. The zoom room link, 

ID and pass for the FCV PWG meeting are in our usual drupal agenda page below. 

Please also keep in mind that all the preliminary plots should have already been there 

in the summary area below. 

Best regards, Jiangyong, Prithwish and ShinIchi 

Meeting agenda page with zoom link : https://drupal.star.bnl.gov/STAR/blog/jjiastar/bulkcorr 
Preliminary page : https://drupal.star.bnl.gov/STAR/pwg/bulk-correlations/bulkcorr-preliminary-summary

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--

Ashik Ikbal

Research Associate

Kent State University

Department Of Physics

Kent, OH 44242, USA

Contact no.s: +1 631-504-7647 (USA)

                      +91 8250216234 (India)

Alternate e-mails: asheikh2 AT kent.edu

                             ashik AT rcf.rhic.bnl.gov

                             ashik.ikbal.sheikh AT cern.ch

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Sooraj Radhakrishnan

Research Scientist,

Department of Physics

Kent State University

Kent, OH 44243

Physicist Postdoctoral Affiliate

Nuclear Science Division
Lawrence Berkeley National Lab
MS70R0319, One Cyclotron Road

Berkeley, CA 94720

Ph: 510-495-2473

Email: skradhakrishnan AT lbl.gov

--

Ashik Ikbal

Research Associate

Kent State University

Department Of Physics

Kent, OH 44242, USA

Contact no.s: +1 631-504-7647 (USA)

                      +91 8250216234 (India)

Alternate e-mails: asheikh2 AT kent.edu

                             ashik AT rcf.rhic.bnl.gov

                             ashik.ikbal.sheikh AT cern.ch

--

Ashik Ikbal

Research Associate

Kent State University

Department Of Physics

Kent, OH 44242, USA

Contact no.s: +1 631-504-7647 (USA)

                      +91 8250216234 (India)

Alternate e-mails: asheikh2 AT kent.edu

                             ashik AT rcf.rhic.bnl.gov

                             ashik.ikbal.sheikh AT cern.ch

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