STAR Correlations and Fluctuations PWG

[Nu Xu <nxu AT lbl.gov>]

Dear Daniel,

Please send us the latest version of your talk. I will read it through today.

Regards,
Nu

> On May 12, 2024, at 12:14 AM, Kincses Dániel via Star-cf-l 
> <star-cf-l AT lists.bnl.gov> wrote:
> 
> Dear Hanna, Nu,
> 
> Thanks for the further comments, I have updated the slides.
> 
> I define the following quantities on slide 3:
> x: particle coordinate vector, p: particle momentum
> S(x, p): single-particle phase-space density (called single-particle source 
> or emission function)
> r: pair separation, K: pair average momentum
> D(r, K): pair phase-space density (or pair source)
> and S depends on particle momenta, D depends on pair average or total 
> momentum.
> This is the same as equations 2 and 3 in Ann.Rev.Nucl.Part.Sci. 55 (2005) 
> 357-402.
> There, s(p,x) is used for what I call S(x,p), and also, in that paper, 
> S_P(r) is used for what I call D(r, K), with also P=K.
> 
> I made the following modifications:
> Slide 3: 
>     • I distinguish S and D more clearly by writing out "Single particle 
> phase-space density (emission func.)"
>     • I added the reference to the bottom of the slide to 
> Ann.Rev.Nucl.Part.Sci. 55 (2005) 357-402 
> Slide 4: 
>     • I also added the note to the top "S: Single particle phase-space 
> density (emission function)"
> Slide 15:
>     • I added a further note that the core-halo picture mentioned here is 
> not the same as the EPOS core-corona notation; it is just a coincidence 
> that they are named the same. In EPOS, the core is the part coming from the 
> hydro evolution, and the corona contains high-momentum particles (jets).
> Slide 19:
>     • According to Hanna's advice, I changed the bullets, and now it states 
> "Observation" and "Possible interpretation" instead of "Conclusion".
> 
> Thanks,
> DanielFeladó: 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: 2024. május 12., vasárnap 2:47
> Címzett: star-cf-l AT lists.bnl.gov <star-cf-l AT lists.bnl.gov>
> Másolatot kap: Hanna Paulina Zbroszczyk <hanna.zbroszczyk AT pw.edu.pl>
> Tárgy: Re: [Star-cf-l] STAR presentation by Daniel Kincses for CPOD 2024 
> submitted for review
>  Dear Daniel and All,
> 
> Thanks for explanations. 
> 
> Slide 3/4:
> Then, it would help if you wrote the formulas taken from 
> Ann.Rev.Nucl.Part.Sci. 55 (2005) 357-402 paper.
> Take then equations 2 and 3. 
> I suggest distinguishing between the emission function that depends on 
> momenta and positions and the source function depending on relative 
> positions only (with identical velocities and total momentum). 
> Slide 15:
> Regarding S_{core} and R_{halo}, slide 26 (backup) would help if you extend 
> the discussion related to UrQMD / EPOS3 parts about core/corona 
> contributions. 
> Slide 19:
> About Nu’s concern, I agree that the statement about increased particle 
> density, as does come from your model study, is not directly related to the 
> presented experimental results, so you may restructure your summary slide 
> by adding in the end bullet about possible physics messages, making the 
> same time your statement lighter. 
> I hope it helps. 
> 
> Thanks,
> Hanna
> 
> 
> Prof. Hanna Zbroszczyk, PhD, DSc, Eng.
> 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
> 
> 
> 
> Wiadomość napisana przez Nu Xu via Star-cf-l <star-cf-l AT lists.bnl.gov> w 
> dniu 12.05.2024, o godz. 00:44:
> 
> Hi Mate and All,
> 
> Thank you for these explanation's.
> All you have said is possible, but we should conclude with results, not 
> speculations. The result should be presented in the talk.
> 
> Regards,
> Nu
> 
> On May 11, 2024, at 1:22 PM, Mate Csanad <csanad AT bnl.gov> wrote:
> 
> Hi Nu,
> 
> Sorry to amend myself, but there is an additonal point: if densities are 
> larger, freeze-out may happen later, and hence larger tails appear in the 
> freeze-out distribution. This may be the effect in the end that causes 
> alpha to decrease with increasing energy.
> 
> Best regards,
> Mate
> 
> 2024. 05. 11. 22:04 keltezéssel, Mate Csanad írta:
> Hi Nu,
> I am sorry if I misunderstand the point you raise, but maybe it helps 
> clarifying things if I try to elaborate what Daniel is trying to say in the 
> discussed slide.
> The idea (speculation) is that the total hadron multiplicity is increasing 
> with collision energy, and if this increase is faster than the quark-hadron 
> (or chemical) freeze-out volume, then also hadron number density also 
> increases with collision energy. In turn, this increase in density (and a 
> possible increase in temperature) decreases the mean free path in the 
> hadron gas phase. This is directly connected to the nature of diffusion, 
> how anomalous it is, to what extent it differs from normal diffusion. The 
> larger the difference, the more anomalous the diffusion is, the smaller 
> alpha may become.
> In other words, the following things happen with increasing collision 
> energy:
> 1) Increase in the number density of the hadron gas
> 2) Decrease in the mean free path in the hadron gas
> 3) More frequent hadron collisions, and more of them in total
> 4) More anomalous nature of hadron diffusion (in the hadron gas)
> 5) Smaller alpha values, i.e., larger tails of the spatial distribution of 
> the last points of scattering (hadron kinetic freeze-out distribution)
> This line of argumentation in fact can be checked in UrQMD, or any simle 
> hadron gas model, how the spatial freeze-out distributions change with 
> collision energy - was however not yet done. What is known (published) is 
> that in EPOS (including UrQMD), alpha is a bit smaller at LHC than at top 
> RHIC energy. Furthermore, Daniel's recent UrQMD results indicate that alpha 
> is even larger in pure UrQMD at 3.2 or 3.9 GeV (and there is also a small 
> increase from 3.9 to 3.2 GeV ).
> I'm not sure if this clears the point to be conveyed, but Nu, please let 
> Daniel and me know if we misunderstood what you wrote.
> Thanks, best regards,
> Mate
> 2024. 05. 11. 16:56 keltezéssel, Nu Xu via Star-cf-l írta:
> Dear Daniel and All,
> 
> Thank you for the quick responses.
> Regarding to the first reply to my first point, I am still not convinced.
> Two particle correlations do not ‘see' the density because it only be 
> effective when the strong interactions are ceased. Source size parameters 
> do not reflected direct the size ( -> density) due to other effects such as 
> collective flow.
> 
> The claim of density effect could be misleading.
> 
> Regards,
> Nu
> 
> On May 11, 2024, at 5:18 AM, Kincses Dániel <kincses AT ttk.elte.hu> wrote:
> 
> Dear Hanna, Nu,
> Thank you for the comments and suggestions, I updated the slides 
> accordingly.
> I also compiled a list of answers here:
> https://urldefense.com/v3/__https://docs.google.com/document/d/1ukHI7AjBrvGqx38Rw92UbKR8o-YjG7i_s6NkDqQ3Gsw/edit?usp=sharing__;!!P4SdNyxKAPE!CZR6W96_ct1ht2jBBbzhX_QQcYy3nG_lF2UMvvYdbS4Fd36N1EHQ3ub83NIVl_9Nd9POaT-FWItK2Sw1Pso$
> 
> Thanks,
> Daniel
> 
> Feladó: Star-cf-l <star-cf-l-bounces AT lists.bnl.gov>, meghatalmazó: Nu Xu 
> via Star-cf-l <star-cf-l AT lists.bnl.gov>
> Elküldve: 2024. május 11., szombat 4:01
> Címzett: STAR Correlations and Fluctuations PWG <star-cf-l AT lists.bnl.gov>
> Másolatot kap: Nu Xu <nxu AT lbl.gov>
> Tárgy: Re: [Star-cf-l] STAR presentation by Daniel Kincses for CPOD 2024 
> submitted for review
>  Dear Daniel and All,
> 
> I agree with all comments/suggestions offered by Hanna.
> In addition, I have the following two suggestions:
> 
> 1) slide 19 - Summary: (i) “Increasing particle density → rescattering 
> decreases 𝜶?”  the HBT refers to the freeze-out particle correlation. Why 
> does it sensitive to density before freeze-out? It appears that at higher 
> collision energy or more central collisions, the source is further away 
> from Gaussian. I suggest remove the speculation. (ii) Lower - right figure: 
> remake the plot till x-axis to 300 GeV;
> 
> 2) slide 18 - last bullet: replace "No non-monotonic trend observed yet” by 
> “No non-monotonic trend in alpha observed yet”;
> 
> Hope this is helpful.
> 
> Nu
> 
> On May 10, 2024, at 3:34 PM, Hanna Paulina Zbroszczyk via Star-cf-l 
> <star-cf-l AT lists.bnl.gov> wrote:
> 
> Dear Daniel,
> 
> Thanks for your update, I have a few more remaining comments:
> 
> Slide 3:
> I still don’t understand why S function depends on spatial and momentum 
> coordinates.
> Provide a reference here. Why do you use different to Koonin-Pratt equation?
> 
> Slide 4:
> Once more about the statement dla Levy shape of the correlation function is 
> not a consequence of conversion from 3D to 1D case. Can you prove this? Do 
> you have any example that if your source can be described by Gaussian 
> distributions in 3D, you will end up with Gaussian in 1D as well?
> 
> Slide 6:
> Again: speaking about critical behavior, do you have prediction of D(r) 
> when \alpha is 0.5?
> Do you have an example of the correlation function for such a case?
> 
> Slide 15:
> Can you discuss here how S_{core} and S_{halo} look like?
> 
> Slide 18:
> I suggest not to discuss CMS results, especially when you don’t show them 
> (which is ok).
> 
> Kind regards,
> Hanna
> 
> Prof. Hanna Zbroszczyk, PhD, DSc, Eng.
> 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
> 
> 
> 
> Wiadomość napisana przez webmaster--- via Star-cf-l 
> <star-cf-l AT lists.bnl.gov> w dniu 06.05.2024, o godz. 17:12:
> 
> Dear star-cf-l AT lists.bnl.gov members,
> 
> Daniel Kincses (kincses AT ttk.elte.hu) has submitted a material for a review,
> please have a look:
> https://drupal.star.bnl.gov/STAR/node/67691
> 
> Deadline: 2024-05-20
> ---
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> webmaster AT www.star.bnl.gov
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