STAR Flow, Chirality and Vorticity PWG

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

Dear Yicheng,

I am not sure if your response addresses my question. For the SP/PP method to work, we need the \Delta rho_00 of the rho-meson, not the phi-meson, to be maximized in PP. This is a specific condition required by your procedure. Are there any experimental measurements to support this? A clear and direct answer would be greatly appreciated. 

Thanks,

Aihong

On Nov 26, 2024, at 1:07 PM, Feng, Yicheng <feng216 AT purdue.edu> wrote:

Hi Aihong, 

The STAR nature paper is an experimental paper. The conclusion was that the phi meson global spin alignment measurement can only be explained by color field fluctuations of the participant interaction. 

Sincerely,

Yicheng

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From: star-fcv-l-request AT lists.bnl.gov <star-fcv-l-request AT lists.bnl.gov> on behalf of Tang, Aihong <aihong AT bnl.gov>
Sent: Monday, November 25, 2024 8:52 PM
To: star-fcv-l AT lists.bnl.gov <star-fcv-l AT lists.bnl.gov>
Subject: Re: [[Star-fcv-l] ] AuAu 200GeV CME paper draft and analysis note

 

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Hi Yicheng,

Thank you for your reply. You referenced a theoretical work, which I am neither questioning nor debating. My question is simply this : since we are writing this experimental paper, do we have experimental evidence to support our statement and underlying assumptions ? 

Best,

Aihong

On Nov 25, 2024, at 8:07 PM, Feng, Yicheng <feng216 AT purdue.edu> wrote:

Hi Aihong, 

We had a reference right in that statement 

[30] Z.-T. Liang and X.-N. Wang, Spin alignment of vector mesons in non-central A+A collisions, Phys. Lett. B 629, 20 (2005)

From my reading, the conclusion of the STAR nature paper of phi spin alignment (since there is no rho measurement) is that only the color field fluctuation can explain the measurements. 

Those QCD effects should be involved with the collision zone created by the participants.

Sincerely,

Yicheng

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From: star-fcv-l-request AT lists.bnl.gov <star-fcv-l-request AT lists.bnl.gov> on behalf of Tang, Aihong <aihong AT bnl.gov>
Sent: Monday, November 25, 2024 3:34 PM
To: star-fcv-l AT lists.bnl.gov <star-fcv-l AT lists.bnl.gov>
Subject: Re: [[Star-fcv-l] ] AuAu 200GeV CME paper draft and analysis note

 

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Dear Yicheng,

Thank you for your post. We'd like to revisit a question regarding the strong assumption about global spin alignment and its behavior in PP and SP.

For the PP/SP method to be valid, one must assume that the \Delta rho_00 of the rho-meson reaches its maximum along PP, similar to the behavior of v2. While this assumption could be correct or incorrect, there are currently no measurements to either support or refute it. Could you kindly elaborate on the evidence supporting your statement that "Because it (global spin alignment) is an effect of spin-orbit coupling in the participant zone, such a contribution would behave also like the flow-induced background and thus be subtracted in this SP/PP method" ?

Thanks,

Aihong

On Nov 22, 2024, at 2:07 PM, Feng, Yicheng <feng216 AT purdue.edu> wrote:

Hi FCV, 

We had a PWGC preview of the CME paper proposal and got many valuable comments. We’ve documented it here: 

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

We have prepared a paper draft and analysis note. 

paper draft: https://drupal.star.bnl.gov/STAR/system/files/AuAuFcme_Paper_Pwg_v4.pdf

analysis note: https://drupal.star.bnl.gov/STAR/system/files/AuAuFcme_Note_Pwg_v4.pdf

More details can also be found on the drupal webpage: 

https://drupal.star.bnl.gov/STAR/blog/fengyich/fcme-AuAu-200-GeV-after-background-estimate

If you have any questions/comments, please let us know.

Sincerely,

Yicheng