STAR Correlations and Fluctuations PWG

[Somadutta Bhatta <somadutta.bhatta AT stonybrook.edu>]

Dear Rutik,

Claiming b=-0.5 or independent superposition for 200 GeV in slide 17 is inconsistent with previous publication from STAR (Phys.Rev.C 72,044902 (2005)).

Please see the attached plot from STAR paper (PhysRevC.99.044918 (2019)) which you use in slide 17. The same paper also includes a ratio of data wrt power-law fit. 

There is a deviation in mid-central (between 2.5-5%)  wrt power law (also mentioned in the paper), consistent with previous STAR publication Phys.Rev.C 72,044902 (2005). This paper clearly says that there is a deviation from power-law scaling! 

This deviation from the expected 1/sqrt(Npart) or the power law exponent of -0.5 is due to genuine correlations within particles beyond independent superposition.

Therefore, it is not accurate to claim uncorrelated sources on the slides.

My suggestion would be to not claim independent superposition for 200 GeV and 2.76 TeV as it is not correct.

In addition, The figure in Slide 17 is not from the reference mentioned on the slides. The correct reference should be PhysRevC.99.044918 (2019).

Thanking You,

Som

On Thu, Feb 8, 2024 at 12:05 PM Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:

Hello Somadutta and Conveners,

I have made the changes accordingly, thank you for the input!

link: https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver3.pdf

Best,

Rutik Manikandhan

PhD Candidate, Experimental High Energy Group

Physics Dept.

University of Houston

On Thu, Feb 8, 2024 at 8:32 AM Somadutta Bhatta <somadutta.bhatta AT stonybrook.edu> wrote:

Dear Rutik,

Thank you for sharing your nice slides for WWND.

I have a few comments on claims about the independent superposition scenario (particle production from uncorrelated sources) at 200 GeV and 2.76 TeV made in Slide 17 and 18 of your presentation.

Your slides have the following statements:

Slide 17: Power law seems to describe the data at 200 GeV, implying an independent sources scenario
Slide 18: STAR 200 GeV and ALICE 2.76 TeV follow power law (b=-0.5). 

In previous publications from STAR/ALICE studies of mean pT fluctuations (at 200 GeV and 2.76 TeV), they have reported the existence of genuine correlations beyond the independent sources scenario. A power-law fitting parameter of exactly -0.5 implies that the produced particles are from independent pp-like sources, whereas, any value of the parameter larger than that implies the existence of genuine dynamical correlations in excess of independent superposition.

In the ALICE paper (Fig 5 in https://arxiv.org/pdf/1407.5530.pdf), the power-law fitting for sqrt(K2) reports a value of power-law exponent ~0.45 at 2.76 TeV, whereas, STAR measurements (Fig 3 in https://arxiv.org/pdf/nucl-ex/0504031.pdf) reports significantly larger correlations than HIJING calculations (HIJING is expected to follow independent superposition exactly, see https://arxiv.org/pdf/2112.03397.pdf). A HIJING model comparison is also shown in the ALICE paper as well with the same conclusion.

These observations imply that particle production in data is not only from uncorrelated sources and that there exists genuine dynamical correlations at 200 GeV as well as 2.76 TeV deviates from independent superposition.

Therefore,  I think claiming that  "STAR 200 GeV and ALICE 2.76 TeV follow power law"  might be misleading and needs to be fixed on the slides.

Warm regards,

Som

On Thu, Feb 8, 2024 at 8:38 AM Rutik Manikandhan via Star-cf-l <star-cf-l AT lists.bnl.gov> wrote:

Hello Conveners,

Here is the updated version of the talk: https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver_2.pdf

Best,

Rutik Manikandhan

PhD Candidate, Experimental Nuclear High Energy Group

Physics Dept.

University of Houston

On Wed, Feb 7, 2024 at 9:10 AM Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:

Hello Conveners,

Here is the updated version of the talk for WWND 2024.

https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver1.pdf

Best,

Rutik Manikandhan

PhD Candidate, Experimental High Energy Group

Physics Dept.

University of Houston

On Sun, Feb 4, 2024 at 7:51 PM Nu Xu <nxu AT lbl.gov> wrote:

Hi Rutik,

I read your draft already but did not write to you because we will discuss on Thursday.
Regards,
Nu

> On Feb 4, 2024, at 5:27 PM, Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:
>
> Hello Nu,
> Could you please review my talk for WWND?
> Thank you!
> Best,
> Rutik Manikandhan
> PhD Candidate, Experimental High Energy Group
> Physics Dept.
> University of Houston
>
>
> ---------- Forwarded message ---------
> From: webmaster--- via Star-cf-l <star-cf-l AT lists.bnl.gov>
> Date: Thu, Feb 1, 2024 at 2:18 PM
> Subject: [Star-cf-l] STAR presentation by Rutik Manikandhan for WWND 2024 submitted for review
> To: <star-cf-l AT lists.bnl.gov>
> CC: <webmaster AT star.bnl.gov>
>
>
> Dear star-cf-l AT lists.bnl.gov members,
>
> Rutik Manikandhan (manikandhan.rutik AT gmail.com) has submitted a material for 
> a review, please have a look:
> https://drupal.star.bnl.gov/STAR/node/66691
>
> Deadline: 2024-02-11
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--

Thanking You,

Yours Sincerely,

Somadutta Bhatta,

Relativistic Heavy Ion Group,

Stony Brook University

--

Thanking You,

Yours Sincerely,

Somadutta Bhatta,

Relativistic Heavy Ion Group,

Stony Brook University