STAR HardProbes PWG

[Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>]

Hi Tong,

Please find my reply inline.
And looking forward to seeing your updated presentation slides.

On 2022-10-02 07:43, Tong Liu wrote:
> Hi Nihar,
>
> Thanks for your comments. Please find my responses below-- those not
> mentioned are applied to my slides already. However I'd like to take
> until Sunday night and hopefully make some more changes to them before
> uploading again, since we already have a lot to discuss here.
>
> Title: good catch; I meant “high-pt”. One of the worst places to
> have a typo :p
> Slide#3:
>
> _Do you want to say something about right side plots? Any link to your
>
> analysis…please point out that.
> Here it’s just an introduction to high pt hadron as a proxy to jet
> quenching effect. The plot I used is the Au+Au high-pt hadron Raa,
> which is going to be used later as well; in the text I was really
> trying to be general and not talk about any specific measurement, but
> I might talk about it orally. If you think it’s too much though I
> can take it off; but I’d say let’s wait till a first rehearsal.

OK. that's fine.

> Also it might be a good idea to put this slide right after the title
> slide?
> Slide#4:
>
> STAR TPC eta acceptance is |eta| < 1.4 (without iTPC)
>
> What acceptance you are quoting here?
> I'm pretty sure it's |eta|<1… Please see slide 4 in
> https://indico.cern.ch/event/689846/contributions/2947105/attachments/1635225/2608617/Yichang-ChiYang.pdf
> [1]
> Slide#6
>
> _Can you please remind me where do you get this "p+p uncertainty"?
>
> That comes from this paper:STAR Phys. Rev. Lett. 91, 172302 (2003)
> Slide#10:
>
> It is important to mention for Au+Au, d+Au, and Cu+Cu, what pT ranges
>
> were used?
>
> It’s also using 5.1-10 GeV, same as isobar. The statement at the
> bottom of the graph was meant for all measurements, but apparently it
> was not clear enough. Any suggestions?

I would add one bullet mentioning this.

> Slide#12:
>
> _ you have now two models: I) HG-PYTHIA QM2022 preliminary and II) new
>
> results that you labeled as "X+X N_hard"
>
> AFAIK, the difference between I) and II) is due to choice of N_hard
> and
>
> N_part . Is not that?
>
> But from your labels it seems for I) you used pT>5 GeV, and for II)
>
> N_hard is used but all pT range.
>
> Is that true?
> _ Why your uncertainty band for I) QM2022 preliminary results has been
>
> changed? It looks wider band in your preliminary results.
> OK let me explain further here… what the HG-PYTHIA model does is, it
> generates a Glauber-level collision, throw a Poisson dice and
> determine how many hard collisions each NN collision has (Nhard). Then
> it goes to PYTHIA and ask for a p+p collision with nMPI=Nhard (yeah
> that part I don’t understand yet either); then all the tracks from
> all the PYTHIA collisions are stacked together to be the synthetic
> event. Here in the plot, both options categorized events into
> centralities with the “refmult” of this synthetic event, but the
> “benchmark values” are calculated in different ways: in the
> “Nhard” option, the average Nhard in each centrality class is
> compared to <Nhard> of pp collisions, while in the “Y_ch” option,
> the invariant yield of 5 GeV+ tracks is used (<Ncoll> scaling is
> applied in both cases, of course). I didn’t use any <N_part> in this
> baseline beyond the x axis.
> As for the change to QM prelim, that one  was easy: I squeezed much
> larger statistics out of the simulation. In fact this one is still
> statistical error only, and I’ll try to get a crude systematics in
> the next week.

Ok, I got it some extent now.



Thank you
Nihar
> Slide#14:
>
> Do you have associated systematic uncertainty for <Ncoll> and <Npart>
>
> scaled?
>
> The systematic uncertainty assigned to <Ncoll> and <Npart> by the
> centrality group is VERY small, and I suspect they are correlated
> between species, so they also largely cancel out.
>
> Tong Liu
> Ph.D. Student '2023
> Physics Dept., Yale University
>
> Tel: 203-435-2130
>
> On Sat, Oct 1, 2022 at 3:03 AM Nihar Sahoo via Star-hp-l
> <star-hp-l AT lists.bnl.gov> wrote:
>
> > Hello Tong,
> >
> > Please find my comments below  on your nice presentation slides.
> >
> > Slide#1:
> > Title: System size dependence of pT hadron yield modification…"
> > ->
> > "System size dependence of hadron yield suppression…" or something
> > like
> > that
> > Here, "pT hadron yield modification" sounds awkward.
> >
> > Slide#3:
> > _Title: "…QGP probe" -> "…QGP Probe"
> > _"..lose energy to QGP" -> "… lose energy in QGP"
> > _"…RAA: comparison to p+p collisions" -> not quite right? Define
> > RAA
> > using Au+Au and nuclear thickness function..
> > It is important for your previous bullet for Npart and Ncoll
> > _Do you want to say something about right side plots? Any link to
> > your
> > analysis…please point out that.
> >
> > Slide#4:
> > STAR TPC eta acceptance is |eta| < 1.4 (without iTPC)
> > What acceptance you are quoting here?
> >
> > Slide#6
> > _Can you please remind me where do you get this "p+p uncertainty"?
> >
> > Slide#8-9
> > I would make that blue box transparent such that the data points can
> > be
> > visible behind.
> >
> > Slide#10:
> > It is important to mention for Au+Au, d+Au, and Cu+Cu, what pT
> > ranges
> > were used?
> >
> > Slide#12:
> >
> > _ you have now two models: I) HG-PYTHIA QM2022 preliminary and II)
> > new
> > results that you labeled as "X+X N_hard"
> > AFAIK, the difference between I) and II) is due to choice of N_hard
> > and
> > N_part . Is not that?
> > But from your labels it seems for I) you used pT>5 GeV, and for II)
> > N_hard is used but all pT range.
> > Is that true?
> >
> > _ Why your uncertainty band for I) QM2022 preliminary results has
> > been
> > changed? It looks wider band in your preliminary results.
> >
> > Slide#14:
> > Do you have associated systematic uncertainty for <Ncoll> and
> > <Npart>
> > scaled?
> >
> > Cheers
> > Nihar
> >
> > On 2022-09-29 09:54, webmaster--- via Star-hp-l wrote:
> > > Dear Star-hp-l AT lists.bnl.gov members,
> > >
> > > Tong Liu (tong.liu AT yale.edu) has submitted a material for a
> > review,
> > > please
> > > have a look:
> > > https://drupal.star.bnl.gov/STAR/node/61208
> > >
> > > Deadline: 2022-10-11
> > > ---
> > > If you have any problems with the review process, please contact
> > > webmaster AT www.star.bnl.gov
> > > _______________________________________________
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>
>
> Links:
> ------
> [1] 
> https://indico.cern.ch/event/689846/contributions/2947105/attachments/1635225/2608617/Yichang-ChiYang.pdf