STAR Correlations and Fluctuations PWG

[米柯 <mike1996 AT mails.ccnu.edu.cn>]

Dear Hanna,

Thank you so much for your useful comments, please see me answer below.

1.Preliminary plots have been uploaded to my blog link: 

https://drupal.star.bnl.gov/STAR/blog/kmi/preliminary-aps2021-proton-xi-correlation-function

2.Slide 7: what is the reason to place here so many details about particle reconstruction?

Are you going to discuss details about these differences?

If not, I recommend providing general info about particle reconstruction; for many cases, the selection criteria are the same (e.g., nSigma, rapidity, etc..). This table can be moved to backup, you can provide just general information. 

—>I have moved table into backup. 

3.Slide 9: Your definition of k* is incorrect. k* calculated in PRF reference means momentum of the first particle of the pair.Do you consider PRF reference? Do you use k* variable? Using PRF is correct for nonidentical particles combinations. You can add a simple plot illustrating what k* considered in PRF reference is. 

—>Yes,we consider it in pair reference frame . I changed the definition to “k* is momentum of particle in pair reference frame” 

 

Having here cascade purity, it would be nice to have proton’s purity too. 

—>Proton purity plot added

I also don’t understand why you define proton’s purity as P(proton) = S/(S+B) * Fr(proton).

You should consider PID probability instead of S/(S+B) in the case of protons.

—>Changed

4.Slide 10: You state here ~3.9\sigma (central) and ~4\sigma (peripheral), but it is valid only if you assume Coulomb interaction in case of source with radius = 3 fm (central) and radius = 2 fm (peripheral). These numbers would change if you consider different source sizes. From these plots, I don’t understand why you choose these source sizes for your correlation functions. Add explanation here. 

—>Based on the paper you send and the antiproton-antiproton nature paper , the appropriate choice of source size is ~3.7~4fm for central and 2.75~3fm for peripheral. So we choose 3.5/4/4.5/5 fm(central) and 2/2.5/3/3.5 fm(central) for comparison .Also we calculate the significance of these eight source size , deviation of these eight different source sizes are all larger than 3sigma .What’s more ,we are going not to mention significance in this talk .

From other baryon studies, we know that source sizes should be larger, for example, for the proton-proton case, in the case of central collisions, source size can be around 4 fm and bigger. 

Also, you should mention that feed-down correction taking into account residual correlations is not implemented here.

—>Added on slide 10 “Weak decay feed-down is corrected, but residual correlations are not studied yet."

5.Slide 11: I would be very careful showing this result. You show a ratio of two correlation functions taking into account sources of sizes of 2 and 3 fm, but you don’t prove they are the best fits. You never show the fit taking into account full FSI for a single correlation function. You also show the ratio of functions assuming just Coulomb interaction, indicating it is more or less close to the unity. However, it can be just an example of such source sizes.

—>In order to show more comparison ,we take more two ratios (3fm/4fm and 3fm/5fm both for Coulomb and Strong interaction) . If we focus on one combination, coulomb potential ratio can largely cancelled (NOT entirely) compared to only strong interaction ratio .We will consider the residual Coulomb effect into fitting part , however fitting will not be shown on this meeting .  Future fitting results will give us the exact source size number . Here we just show the comparison .

Update slide has been uploaded into same link , please find it through :

https://drupal.star.bnl.gov/STAR/node/54563

Best regards,

Ke

2021年4月9日 下午10:53，Hanna Paulina Zbroszczyk via Star-cf-l <star-cf-l AT lists.bnl.gov> 写道：

reference