STAR Correlations and Fluctuations PWG

[傅川 <fuchuan AT impcas.ac.cn>]

Dear ShinIchi,
             Thank you for your comments/questions.
Latest UrQMD pL r0 (RMS of r* (pair distance in PRF)) is larger compared to 
previous results. 
Please find the reason below:
The CF is effected by source size r0 as well as \vec{k*}.\vec{r*}. 
In data and UrQMD, there exist a bit angle correlations between 
\vec{k*} and \vec{r*} (\vec{r1} - \vec{r2}) caused by collective behavior, 
it has small effects on pL CF, while we see the effect is non-negligible in 
UrQMD 
pL CF within stat. error. In previous pL LL curve production, the phase space 
did not include this angle correlation, so previous pL source size r0 is 
underestimated. 
Now this angle correlation was included in pL LL curve production.

We will include this angle correlation in p-p LL curve production, 
and fit to pp CF from UrQMD and data, then get updated pp source size.
Hope this can resolve the issue on pp source size you point out.     

I do not understand how to take average of both p and Lambda with natural 
ratio in the UrQMD.
In CRAB package, the pair distance in PRF (r*) is an important input 
parameter for correlation calculation,
and it is directly related to the CF calculation.
In UrQMD, we calculated the pL r* pair by pair like CRAB code done, and get 
the RMS of r*.    

Please let me know if there is any questions/comments.

Best regards,
Chuan

> -----原始邮件-----
&gt; 发件人: "EsumiShinIchi via Star-cf-l" <star-cf-l AT lists.bnl.gov>
&gt; 发送时间: 2024-03-19 23:23:38 (星期二)
&gt; 收件人: "fuchuan AT mails.ccnu.edu.cn" <fuchuan AT mails.ccnu.edu.cn>
&gt; 抄送: EsumiShinIchi <esumi.shinichi.gn AT u.tsukuba.ac.jp>, "STAR 
Correlations and Fluctuations PWG" <star-cf-l AT lists.bnl.gov>
&gt; 主题: [Star-cf-l] Some more questions on your talk today
&gt; 
&gt; Dear Chuan
&gt; On Fig.4 in your slide 14 from today, the experimental data and 
&gt; UrQMD are now comparable, which were not really the case in your 
&gt; previous presentation (sorry, if I’m wrong), so I first like to know 
what 
&gt; has changed. I would also like to understand why RMS is quite different 
&gt; (especially for p-p system), although it would give the true geometry 
&gt; with expanding kinematics, if we apply the same kinematic cuts as 
&gt; for the correlation and L.L.-fitting analysis. Thank you very much for 
&gt; the very nice analysis and results. 
&gt; Best regards, ShinIchi
&gt; 
&gt; PS : Sorry for asking the same question, the Rg is given by 
&gt; single track, so do you take average of both p and Lambda 
&gt; with natural ratio in the UrQMD for p-Lambda system? 
&gt; 
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