STAR HardProbes PWG

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

Hi Tong,

If you are around, can you please join today's reserved day HP-pwg 
meeting?
I have some questions on your results, it would be good if we can 
discuss this online.

Thank you
Nihar

On 2022-10-04 06:11, Tong Liu wrote:
> HI Nihar,
>
> I uploaded a new version of the slides, please take a look. As for the
> pt range in previous results, I decided to do some "subtraction"
> instead of "addition" by removing the word "isobar" from the text on
> figure, so that it looks more like I'm referring to everyone. Please
> let me know what you think about it. Also I'll try to push on the
> pythia MPI side, but I'm not very sure I'll be able to get anywhere
> significant beyond where I am now. Let's assume this is the message we
> are going to give, and I'll let you know if I dig up something.
>
> Tong Liu
> Ph.D. Student '2023
> Physics Dept., Yale University
>
> Tel: 203-435-2130
>
> On Mon, Oct 3, 2022 at 9:07 AM Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>
> wrote:
>
> > 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