STAR Correlations and Fluctuations PWG

[Sooraj Radhakrishnan <skradhakrishnan AT lbl.gov>]

Hi Rutik,

   Please find some comments from me on your slides below 

S3: BES-II collider program ... 

S3: above --> >=

S3: and the BES-II FXT program ...

S4: Why 150 M? Previous analyses had 260 M good events. May be change to #of events used 

S5: TPC and TOF to reject out of time pileup events?

S7: How do correlated emission from resonance decays etc affect the <p_T> distributions? Mixed-events wont capture these correlations 

S8: How are mixed-events constructed here? Not clear from the cartoon. Do you select for an event with N tracks, one track each from N different events to make the mixed event?

S9: The reference article number seems not correct, could you check? Also, why is the distribution of mean not Gaussian?

S10: What is eta [-1,1] here? Also, do we have uniform acceptance down to pT = 0.15 across the rapidity window at 3 GeV? How does this affect the dynamical fluctuations? For example, see the acceptance plots here https://www.sciencedirect.com/science/article/pii/S037026932200137X

S10: Is the <p_T> expected to be higher at 3 GeV? Or is this an acceptance effect?

S12: How do you apply the efficiency correction? Do you do unfolding or subtract the difference of the mean from the simulation?

S15: Why does the ALICE data point differ from the trend at top RHIC energies?

S16: How does the varying acceptance with rapidity affect the correlations here? Can the 3 GeV measurements be compared to those at higher energies?

S16: The value of the correlator at 3 GeV is closer to the value at LHC energy, and very different from that from UrQMD? What do we conclude here? 

S20: This is the impact of Delta eta between the pairs, but doesnt reflect the detector acceptance effects in the FXT set up

S21: Do we understand the energy dependence? May be the last statement can be made more broad that we are working to understand the energy dependence as well?

Best,

Sooraj

On Sat, Feb 10, 2024 at 4:18 PM Rutik Manikandhan via Star-cf-l <star-cf-l AT lists.bnl.gov> wrote:

Hello Nu,

The idea was that a smaller transverse flow would keep the system together longer 

and hence increase the interactions, but the experimental evidence as you say would imply otherwise,

so I've removed that line.

Here is the updated version : https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver_6_0.pdf

Thank you!

Best,

Rutik Manikandhan

PhD Candidate, Experimental Nuclear High Energy Group

Physics Dept.

University of Houston

On Sat, Feb 10, 2024 at 1:07 PM Nu Xu <nxu AT lbl.gov> wrote:

Dear Rutik and All,

slide 10: What is the experimental evidence to claim “The system remains in a regime of elastic interactions for a longer period of time as
compared to collider energies”? In fact, from pion HBT measurements, one observes that the duration of the pion source becomes longer at higher collision energy.

Best regards,
Nu

> On Feb 10, 2024, at 11:01 AM, Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:
>
> Hello Nu,
> Thank you for your email.
> Here are my replies
>
> 1) slide 10 - last bullet: I do not see the connections with other points. I suggest remove it;
>     I still do not follow what you are talking about. For example, what do you mean by ‘longer time’? Longer compared to high energy collisions or what?
>  Yes, as compared to collider energies, I have added that now.
> 2) Plots on slides 21, 16, 13, 10: add unit for collision energy;
>    Added
> 3) slide 11: STAR QM2022 proceedings: add the Proceedings publication information.
>  Added
>
> Here is the updated version : https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver_6.pdf
>
> Best,
> Rutik Manikandhan
> PhD Candidate, Experimental Nuclear High Energy Group
> Physics Dept.
> University of Houston
>
>
> On Sat, Feb 10, 2024 at 12:40 PM Nu Xu <nxu AT lbl.gov> wrote:
> Dear Rutik and All,
>
> Thank you for the updated draft talk. Here are my suggestions:
> 1) slide 10 - last bullet: I do not see the connections with other points. I suggest remove it;
>     I still do not follow what you are talking about. For example, what do you mean by ‘longer time’? Longer compared to high energy collisions or what?
> 2) Plots on slides 21, 16, 13, 10: add unit for collision energy;
> 3) slide 11: STAR QM2022 proceedings: add the Proceedings publication information.
>
> With these implemented, I sign off.
>
> Nu
>
>
> > On Feb 9, 2024, at 12:22 PM, Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:
> >
> > Hello Nu,
> >
> > I have made the changes as you've asked for.
> > Link : https://drupal.star.bnl.gov/STAR/system/files/WWND__2024_ver_5.pdf
> > Here are our comments for your responses:
> >  1) slide 10 - last bullet: I do not see the connections with other points. I suggest remove it;
> >     The elastic interactions would possibly widen the distribution for <pT> as now more particles gain momentum in either direction.
> > 2) slide 11: It is not clear from the texts if the efficiency is extracted from embedding or other methods. Please make it clear;
> >     The plot has embedding efficiency on it, and I've added a QM reference
> > 3) slide 13: (i) again, the notion for eta is for different frame, please make it consistent. Otherwise it will lead to confusion; (ii) plot: for y-axis, I suggest change the lower limit to something like -0.25;
> >    Changed accordingly
> > 4) slide 16: (i) 2nd-bullet: the sentence is incomplete. Should be something like “Calculations from transport model …”; (ii) The meaning of bullet 3,4,5 is unclear. Not sure what do you want to say;
> >     Changed accordingly and added a relation between Temp and <pT>, we are trying to establish a thermal fluctuations scenario
> > 5) slide 18 - 2nd bullet: the sentence is incomplete. Something like “STAR data from 200 GeV Au+Au collisions …”. The same for the 4th bullet;
> >     Changed accordingly
> > 6) slide 19: It is redundant with respect to slide 18. I suggest remove it.
> >     This slide shows that UrQMD also follows an increase with decreasing centrality and that we might not have sensitivity at most central collisions, so we would like to keep it
> > 7) slide 21 - last bullet: at the end, add “especially at the 3GeV Au+Au collisions. The effect is not yet fully understood” or something like this. This means that we are still thinking about the new result. This is th eke slide of the talk. The UrQMD model is a hadronic transport model. Supposedly, it works better for low energy collisions where partonic medium may not be dominant, see Ref. 5 and 6. However, here as one can see that the model result is totally failed while the model calculations show a reasonable energy dependence of the pT-correlation at higher collision energies. I do not understand why so.
> >    Changed accordingly
> > 8) slide 21 - References: do we need 5 and 6?
> >     Changed accordingly
> >
> > Best,
> > Rutik Manikandhan
> > PhD Candidate, Experimental Nuclear High Energy Group
> > Physics Dept.
> > University of Houston
> >
> >
> > On Fri, Feb 9, 2024 at 12:05 PM Nu Xu <nxu AT lbl.gov> wrote:
> > Dear Rutik and All,
> >
> > Here are my suggestions for the draft:
> > 1) slide 10 - last bullet: I do not see the connections with other points. I suggest remove it;
> >
> > 2) slide 11: It is not clear from the texts if the efficiency is extracted from embedding or other methods. Please make it clear;
> >
> > 3) slide 13: (i) again, the notion for eta is for different frame, please make it consistent. Otherwise it will lead to confusion; (ii) plot: for y-axis, I suggest change the lower limit to something like -0.25;
> >
> > 4) slide 16: (i) 2nd-bullet: the sentence is incomplete. Should be something like “Calculations from transport model …”; (ii) The meaning of bullet 3,4,5 is unclear. Not sure what do you want to say;
> >
> > 5) slide 18 - 2nd bullet: the sentence is incomplete. Something like “STAR data from 200 GeV Au+Au collisions …”. The same for the 4th bullet;
> >
> > 6) slide 19: It is redundant with respect to slide 18. I suggest remove it.
> >
> > 7) slide 21 - last bullet: at the end, add “especially at the 3GeV Au+Au collisions. The effect is not yet fully understood” or something like this. This means that we are still thinking about the new result. This is th eke slide of the talk. The UrQMD model is a hadronic transport model. Supposedly, it works better for low energy collisions where partonic medium may not be dominant, see Ref. 5 and 6. However, here as one can see that the model result is totally failed while the model calculations show a reasonable energy dependence of the pT-correlation at higher collision energies. I do not understand why so.
> >
> > 8) slide 21 - References: do we need 5 and 6?
> >
> > That is all for now.
> >
> > Best regards,
> >
> > Nu
> >
> >
> >
> > > On Feb 9, 2024, at 8:51 AM, Rutik Manikandhan <manikandhan.rutik AT gmail.com> wrote:
> > >
> > > Hello Nu,
> > >
> > > The version is v4 now, and this is the link:
> > > https://drupal.star.bnl.gov/STAR/system/files/WWND_2024_ver4.pdf
> > >
> > > Do let me know if this works for you.
> > > Thank you.
> > >
> > > Best,
> > > Rutik Manikandhan
> > > PhD Candidate, Experimental High Energy Group
> > > Physics Dept.
> > > University of Houston
> > >
> > >
> > > On Fri, Feb 9, 2024 at 10:47 AM Nu Xu <nxu AT lbl.gov> wrote:
> > > Dear Rutik,
> > > Somehow the link to drupal does not work.
> > > Please fix it asap.
> > >
> > > Thank you,
> > > Nu
> >
>

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--

Sooraj Radhakrishnan

Research Scientist,

Department of Physics

Kent State University

Kent, OH 44243

Physicist Postdoctoral Affiliate

Nuclear Science Division
Lawrence Berkeley National Lab
MS70R0319, One Cyclotron Road

Berkeley, CA 94720

Ph: 510-495-2473

Email: skradhakrishnan AT lbl.gov