STAR Correlations and Fluctuations PWG

[Kincses Dániel <kincses AT ttk.elte.hu>]

Dear Hanna,

Toshihiro had a remark on slide 7, he agreed that it is hard to compare to previous results when the documentation is not clear.
However, he suggested that the small difference could still be because of the different datasets,
Run-11 / Run-10 differences. If requested, I can try to repeat the same comparison with the Run-10 dataset.

The rest of the discussion was with Grigory, he had many questions and comments, I try to summarize them briefly below.

- He asked if the binning in Q is not too small for the momentum resolution.

Indeed, it may be larger than what we used here, and we did fits with rebinned

data (where Q-bins are larger). We will show such tests next time.

- He questioned the amount of fluctuation of the subplot (data-fit)/error on

slide 4. This shows the difference between the blue points and the red curve,

divided by the statistical error on the point for each bin. The chi-square is

the sum of the squares of these points, it is very close to the NDF value, and

the confidence level is thus acceptable (this basically means a chi-square

test). It is important as well, that the fluctuation of these points is centered

around zero (this is a T-test), and has a normal distribution, there are no

additional structures on this subplot e.g., as a function of Q (this basically

means a Wilcoxon test). Hence, this subplot confirms that the theory curve is

statistically well describing the data.

- We discussed the systematic uncertainties; he suggested that I also look at

purity corrections, I will try to look into this.

- We discussed furthermore the lambda parameter, its magnitude, and its

systematic uncertainties. It has the largest relative systematic uncertainties

out of the three main parameters, and the largest contributions to this are the

pair cuts and the DCA cut (as expected). A stricter DCA cut leads to a sample

where the fraction of decay pions is smaller, thus lambda will be larger.

- He also questioned the magnitude of the lambda parameter, and whether the

obtained values are too high, or what can explain such high values. There are

lots of different phenomenology results in the literature for expectations on

the mT dependence of lambda, with values up to 0.8-0.9, e.g., see for example

Fig. 3 of Phys.Rev.Lett. 81 (1998) 2205-2208

but there are many such calculations, for example, done in

Phys.Rev.C 97 (2018) 6, 064911

- He also asked what the R parameter means if the source is not Gaussian,

suggesting that it cannot mean the homogeneity length. We responded that indeed

if the source shape is not Gaussian, then the correct way to represent it is the

scale of the distribution that describes it well, in this case, the Lévy-scale

R, the width of the Lévy distribution. It is actually quite interesting that if

the Lévy-alpha has a minimum near the critical point, the Lévy-scale R has a

maximum, then it can very well be that Gaussian radii have a fully monotonic

trend. This is why it is important to investigate source radii with a

Lévy-shaped source. Also note that if the source has a long tail, then the

Gaussian radii are dominated by that tail (maybe created by hadronic

rescattering and not by QGP dynamics), and do not necessarily grasp the true

scale of the source.

I am currently trying to finalize the systematic uncertainty investigations, and 
repeat the analysis for different centrality selections. I am writing an analysis 
note, in which I will try to detail everything, and give more thorough answers
to these questions. Hopefully, I will upload it on drupal within a few weeks.

Thanks, best regards,
Daniel

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Feladó: Hanna Paulina Zbroszczyk <hanna.zbroszczyk AT pw.edu.pl>
Elküldve: 2023. június 12., hétfő 0:16
Címzett: Kincses Dániel <kincses AT ttk.elte.hu>
Másolatot kap: star-cf-l AT lists.bnl.gov <star-cf-l AT lists.bnl.gov>
Tárgy: Re: [Star-cf-l] CF PWG meeting, June 8th, 2023, time: 9:00 (BNL time)

 

Hi Daniel and All,

As I was traveling last Thursday, I could not join the meeting.

I saw your slides from the last meeting.

I heard that your presentation had been intensively commented on during the meeting.

As our meetings are not recorded, and I see only your slides, can you write some more details about your presentation and discussion?

Thanks,

Hanna

Hanna Paulina Zbroszczyk

PhD DSc Eng, Professor WUT

E-mail: hanna.zbroszczyk AT pw.edu.pl

Tel: +48 22 234 5851 (office)

Address:

Warsaw University of Technology

Faculty of Physics

Nuclear Physics Division

Koszykowa 75

Office: 117b (via 115)

00-662 Warsaw, Poland

Wiadomo¶ć napisana przez Kincses Dániel <kincses AT ttk.elte.hu> w dniu 06.06.2023, o godz. 15:17:

Dear Conveners,

I would like to give an update on the Levy HBT analysis at 200 GeV. I will post the slides as soon as possible.

Thanks,
Daniel

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Feladó: Star-cf-l <star-cf-l-bounces AT lists.bnl.gov>, meghatalmazó: Hanna Paulina Zbroszczyk via Star-cf-l <star-cf-l AT lists.bnl.gov>
Elküldve: 2023. június 5., hétfő 16:32
Címzett: star-cf-l AT lists.bnl.gov <star-cf-l AT lists.bnl.gov>
Tárgy: [Star-cf-l] CF PWG meeting, June 8th, 2023, time: 9:00 (BNL time)

 

Dear CF Activists,

We will have our weekly CF PWG meeting on Thursday, June 8th, 9:00 AM 
(BNL time). 

If you would like to contribute, please let us know.

I will be absent as I travel this Thursday but Toshihiro will chair the meeting.

Please try to post your slides at your earliest convenient.
We will connect via Zoom. Please find the connection details under the 
meeting webpage.

Thank you,
Best regards,
Toshihiro and Hanna

https://drupal.star.bnl.gov/STAR/blog/luoxf/correlations-and-fluctuations
https://drupal.star.bnl.gov/STAR/blog/gos/correlations-and-fluctuations-preliminary-plots 

Hanna Paulina Zbroszczyk

PhD DSc Eng, Professor WUT

E-mail: hanna.zbroszczyk AT pw.edu.pl

Tel: +48 22 234 5851 (office)

Address:

Warsaw University of Technology

Faculty of Physics

Nuclear Physics Division

Koszykowa 75

Office: 117b (via 115)

00-662 Warsaw, Poland