STAR Flow, Chirality and Vorticity PWG

[dshen <dshen AT rcf.rhic.bnl.gov>]

Hi Fuqiang, Zhiwan and all,

It was a inspiring discussion on the systematic uncertainty calculations 
yesterday, it pushes me to think.
I tend to agree with Zhiwan and what the blind-analysis did, i.e. use 
denominator of 1/sqrt(12).
The argument was that one shouldn't divide the variation by 1/sqrt(12) 
because the variation isn't proved to be the maximum - minimum, I think 
there is a misunderstanding of the reason behind it.
It isn't based on the assumption that the variation is maximum - 
minimum, the underlying assumption is that the true value falls within 
"default cut" +- "variation".
Let's take an example, say, the default cut is DCA<2, and the systematic 
cut is DCA<1.
The assumption is that the non-biased value is in the interval of (def. 
- |def.-sys.|,  def. + |def.-sys.|), and it can be any value in that 
interval with equal probability (uniform distribution) assuming we don't 
have any pre-knowledge to the best position. That's the reason of why 
people assign |def.-sys.|/sqrt(12) as 1 sigma and use two-side band.
It hasn't to be the maximum - minimum, although it isn't incorrect 
technically to use larger uncertainty, say, use Dca<0.1 to Dca<100.  But 
I think the principal is to provide the best estimate instead of the 
most conservative value.
What variation can be considered as reasonable? I think it is based on 
experience and common sense to a specific physics topic. For CME study, 
like what Zhiwan did, it is reasonable to assume the non-biased value 
falls with in DCA<2 +- |DCA<2 - DCA<1|, for example.

That's my two cents.

Best,
Diyu



On 2023-12-06 05:10, Zhiwan Xu via Star-fcv-l wrote:
> Dear Conveners,
>  I would like to update the paper proposal on the CME search in STAR 
> BES-II.
>  Please kindly add me to the schedule.
>
>  The paper proposal webpage:
>
> https://drupal.star.bnl.gov/STAR/blog/zhiwanxu/Paper-Proposal-Search-Chiral-Magnetic-Effect-RHIC-Beam-Energy-Scan-II
>  The slides:
>   
> https://drupal.star.bnl.gov/STAR/system/files/paper_proposal_CME_BESII_v2.pdf
>
> Best,
> Zhiwan
>
> ------------------------------------
> Zhiwan Xu,
> Department of Physics and Astronomy, UCLA
> zhiwanxu AT physics.ucla.edu
>
> ----- Original Message -----
> From: "subhash via Star-fcv-l" <star-fcv-l AT lists.bnl.gov>
> To: "STAR Flow, Chirality and Vorticity PWG" <star-fcv-l AT lists.bnl.gov>
> Cc: "subhash" <subhash AT rcf.rhic.bnl.gov>
> Sent: Sunday, December 3, 2023 11:21:34 PM
> Subject: [Star-fcv-l] FCV PWG meeting on 06/December/2023 Wed. 9:30 AM 
> EDT
>
> Dear All,
>
> We shall have our weekly FCV PWG meeting this Wednesday (06/Dec/2023) 
> at
> 9:30 AM EDT. If you would like to present please let us know. Please 
> try
> posting your slides by Tuesday. The agenda will be collected at:
> https://drupal.star.bnl.gov/STAR/blog/jjiastar/bulkcorr
>
> Zoom details are copied below.
>
> Thanks and regards,
> Prithwish, Zhenyu and Subhash
>
>
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