STAR Correlations and Fluctuations PWG

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

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,
Daniel

---

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: 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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