STAR HardProbes PWG

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

Hello Youqi,

Please find my reply and queries inline.


On 2022-09-25 23:02, Youqi Song wrote:
> Hi Nihar,
>
> Thanks for the feedback. I updated the slides here:
> https://drupal.star.bnl.gov/STAR/system/files/prelim_request_092522.pdf
>
> Response to unnumbered comments:
>
> Yes, I have three MCs, Herwig, Pythia8 and Pythia6, but what I did
> earlier was just to use Pythia6 for the *misses*, I still did
> unfolding with each of the different MC prior shapes. (Now the plots I
> updated on Friday have both the misses and the unfolded parts with
> different priors). I plotted the fully corrected distributions with
> the different priors together with other sources of sys uncertainty in
> backup slide 1, and I just added a backup slide 2 with just the
> distributions due to prior shape variation.

Ok, that's fine.
> Ok, I've added a slide after slide 15 to show the error breakdown.

I like this comparison plot that is in Slide#16. It looks like at this 
stage both Multifold and RooUnfold give roughly the same uncertainties. 
But we need to go through some other systematic uncertainties (like you 
mentioned below) in future after HQ conf.
> For detector and generator level pT shape smearing, I think the idea
> is to add some smearing to the response matrix itself. Maybe others
> can correct me if I'm wrong.
Not sure if I understand this correctly, this needs a discussion. Could 
you please bring this topic up in your next presentation?
But for HQ, I think it is Ok, the systematic uncertainties you have for 
STAR preliminary.


> Response to numbered comments:
>
> 1. For the detector response systematics, there are hadronic
> correction, tower scale and tracking efficiency variation.
> For hadronic correction, I see how it makes sense to vary in data as
> well, but I learned that Raghav and Isaac didn't vary data for their
> analyses, so I decided to go with how they did it. Also, I tried
> varying data as well, but it didn't have a large effect. See the
> comparison plot I added in slide 12.

Good that you checked this for Hadronic correction.

> For tower scale and tracking efficiency, I am not sure how we would
> vary data. Right now I decreased the tracking efficiency in Geant by
> 4%, and kept data the same. Do you mean that we should drop 4% tracks
> in data for this variation as well?

No, we don't change anything in the data. We can only change in the 
tracking efficiency from embedding.
You mentioned that you only decreased 4%. Have you considered also 
increasing 4% in your systematic uncertainties ? Just to confirm.

> 2. Great, I updated the figure in the slide.

Good, Can you please lower your y-axis scale (say -0.01) so that all the 
markers can be seen properly, particularly at large M region?
(in a plot, all data points should be presented/shown clearly)

> 3. The star markers are MultiFold mass distributions divided by
> RooUnfold mass, so I'm not sure why we want a different style marker?

Suggesting because ratio star marker no need to be the same with 
Multifold marker style. just for cosmetic.

> The error bands are my unfolding systematics and RooUnfold unfolding
> systematics added in quadrature, and then divided by RooUnfold mass
> distribution.

Can you please label your Y-axis accordingly without labeling as "Ratio 
with RooUnfold"?
It is not clear what you have written above. Is not it?
Please put pT range, "STAR Preliminary", and other info like your 
slide#19.

> 4. Great, agreed :)
>
> 5. I updated the legend to include "Detroit tune". I'm not sure we
> want to push for the q vs g separation physics message. Maybe Helen
> and Raghav can say more about this, but my understanding is that the
> quark and gluon jets can have similar fragmentation patterns at 200
> GeV and there can be ambiguity regarding e.g. if you want to call a
> jet initiated from g->qqbar splitting a quark jet or a gluon jet, so
> instead it might be more interesting to treat the jets with different
> M and Q as having different fragmentation patterns.
Ok, that makes sense to me.


Cheers
Nihar

> Best,
> Youqi
>
> On Sun, Sep 25, 2022 at 8:23 AM Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>
> wrote:
>
> > Hello Youqi,
> >
> > Thank you for your update and this information.
> >
> > I have the following comment and questions on your new updated
> > results
> > (plots) and also your notes.
> >
> > > Regarding systematics,
> > > - You might have noticed that the systematic errors for multifold
> > have
> > > gone up by a bit. This is because I realized that before, when
> > doing
> > > herwig and pythia8 shape variations, I was using pythia6 mass
> > > distribution for the misses. Now I changed it so that the misses
> > > contribution
> > > for prior shape variation is also weighted by the mass ratio of
> > herwig
> > > (pythia8) over pythia6.
> >
> > Good that you found out this.
> > If I understand correctly, you have three MCs: Herwig, Pythia8, and
> > Pythia6. You used each of these MC mass distributions for the mass
> > shape
> > variation for sys uncertainties. Earlier, you used Pythia6 for all
> > these
> > cases, but now you corrected it with their respective mass shapes.
> > Is
> > that correct?
> > Could you show (include in your backup) us those mass distribution
> > variations using these three different MC priors? Curious to see the
> >
> > difference due to different fragmentations in the mass distribution.
> >
> >
> > > - After talking with Isaac, I learned that unfolding systematics
> > due to
> > > variation of iteration number and variation of prior shape were
> > treated
> > > as correlated in previous analyses, while I originally had these
> > added
> > > in quadrature. Now I also treat them as correlated by just taking
> > the
> > > largest contribution to the unfolding systematic as the overall
> > > unfolding systematic, and add it in quadrature with detector
> > > systematics.
> >
> > Could you please separate out I) statistical uncertainty, II)
> > Correlated
> > Sys, and III) Uncorrelated Sys in your plot ( using Style2 in
> > slide#16)
> > without adding in quadrature? Please use a smaller marker size to
> > see
> > the stat. Error bar (even if it is small).
> >
> > > - Regarding the question whether there's anything still missing
> > that's
> > > raised during the meeting yesterday, I forgot to mention that we
> > > haven't included detector and generator level pT shape smearing.
> > This
> > > is included in Raghav's and Isaac's analyses because they did 1D
> > > reweighting, but we are not sure if it should be included for
> > > multidimensional unfolding.
> >
> > Hmm, Is not it that the total detector effects (tracking efficiency
> > and
> > pT smearing) are considered using this multifold while you create
> > something like the response matrix? What am I missing here?
> >
> > Comments on your slide#12 (from this email preliminary templet
> > slides)
> >
> > 1. Slide#12: As you have mentioned, you have varied only in the
> > embedding, not in the data. General practice is to vary in the data.
> > But
> > not sure if that will be accurately translated to the variation in
> > the
> > data. It is interesting. i) Then how do you use tracking efficiency
> > (+-4%) variation in embedding to get systematic uncertainties? ii)
> > Can
> > you please do a test where you apply the same variation in the data
> > and
> > use the respective variation in the embedding and then check if you
> > get
> > approximately the same sys. variation between the two cases ?(just
> > for
> > one case which one has a bigger effect).
> >
> > 2. I like Style-4 (slide18) of figure-1 if you don't want to shift
> > the
> > published results. In this case, I would suggest using an open black
> >
> > star for published results and a filled red marker for your new
> > Multifold results. Then you plot your red filled star top on the
> > published results (open back mark). In this case, you don't need to
> > shift the published results, and no confusion, and will look good.
> >
> > 3. SLide19, Fig-1 ratio plot: In this plot, assuming statistical
> > uncertainties cancel out. Are these bands only the ratio of
> > systematic
> > uncertainties? Can you use a separate marker style here in order to
> > avoid your mass distribution red star style?
> >
> > 4. SLide#21: Thank you for including raw distribution here. It looks
> >
> > like there is a noticeable difference between raw and Multifold
> > levels.
> >
> > 5. Slide#23: Thank you for including PYTHIA8 curves. I like this
> > plot
> > and the comparison. Pythia8 and Data are consistent. You could point
> > out
> > that further study is ongoing to explore mass distribution between q
> > vs.
> > g using this |Q| cut. This is the main physics of this |Q| cut here.
> >
> > Right? (Can you label "PYTHiA8" as "PYTHIA8 Detroit tune" or …STAR
> >
> > tune?)
> >
> > Cheers
> > Nihar
> >
> > On 2022-09-23 20:29, Youqi Song via Star-hp-l wrote:
> > > Hi all,
> > >
> > > I have updated my slides for the preliminary request at:
> https://drupal.star.bnl.gov/STAR/system/files/prelim_request_092222_0.pdf.
> > > A few things that I would like to point out:
> > >
> > > Regarding systematics,
> > > - You might have noticed that the systematic errors for multifold
> > have
> > > gone up by a bit. This is because I realized that before, when
> > doing
> > > herwig and pythia8 shape variations, I was using pythia6 mass
> > > distribution for the misses. Now I changed it so that the misses
> > > contribution for prior shape variation is also weighted by the
> > mass
> > > ratio of herwig (pythia8) over pythia6.
> > > - After talking with Isaac, I learned that unfolding systematics
> > due
> > > to variation of iteration number and variation of prior shape were
> > > treated as correlated in previous analyses, while I originally had
> > > these added in quadrature. Now I also treat them as correlated by
> > just
> > > taking the largest contribution to the unfolding systematic as the
> > > overall unfolding systematic, and add it in quadrature with
> > detector
> > > systematics.
> > > - Regarding the question whether there's anything still missing
> > that's
> > > raised during the meeting yesterday, I forgot to mention that we
> > > haven't included detector and generator level pT shape smearing.
> > This
> > > is included in Raghav's and Isaac's analyses because they did 1D
> > > reweighting, but we are not sure if it should be included for
> > > multidimensional unfolding.
> > >
> > > Regarding plotting,
> > > - For fig. 1, I made the mass distribution plot with the same data
> > > points in 4 different styles.- For fig. 1 ratio plot, the error
> > band
> > > is now centered at 1 and is the quadrature of RooUnfold's and
> > > MultiFold's unfolding systematics, divided by the mean values from
> > > RooUnfold.
> > > - For fig. 2, I also included a plot of the M vs Q correlation
> > with
> > > raw data before unfolding.
> > > - For fig. 3, I have pythia8 curves plotted together with my
> > unfolded
> > > mass distributions.
> > >
> > > Please let me know if you have any comments/suggestions.
> > >
> > > Best,
> > > Youqi
> > >
> > > On Wed, Sep 21, 2022 at 5:47 PM Youqi Song <youqi.song AT yale.edu>
> > > wrote:
> > >
> > > > Hi all,
> > > >
> > > > I have uploaded my slides here:
> > > > https://drupal.star.bnl.gov/STAR/blog/youqi/multifold092222
> > > >
> > > > Best,
> > > > Youqi
> > > >
> > > > On Wed, Sep 21, 2022 at 5:04 PM Tong Liu via Star-hp-l
> > > > <star-hp-l AT lists.bnl.gov> wrote:
> > > >
> > > > Hi all,
> > > >
> > > > Please find my pdf in this post:
> https://drupal.star.bnl.gov/STAR/blog/tongliu/Tong-Lius-HP-PWG-updates
> > > > Tong Liu
> > > > Ph.D. Student '2023
> > > > Physics Dept., Yale University
> > > >
> > > > Tel: 203-435-2130
> > > >
> > > > On Wed, Sep 21, 2022 at 3:29 AM Nihar Sahoo via Star-hp-l
> > > > <star-hp-l AT lists.bnl.gov> wrote:
> > > > Hello All,
> > > >
> > > > We got requests from Youqi and Tong to present their results for
> > the
> > > > Hot
> > > > Quark conference.
> > > > And during Youqi's talk at the collaboration meeting, we did not
> > get
> > > > time to have Q&A.
> > > > So let's meet this week to discuss their updates.
> > > >
> > > > Youqi and Tong, can you please send link of your slides in this
> > > > thread
> > > > again?
> > > > (I didn't get your previous emails, the reason I do not know)
> > > >
> > > > If anybody wants to discuss their results, please let us know.
> > > >
> > > > HP-pwg weekly meeting Drupal page:
> https://drupal.star.bnl.gov/STAR/pwg/Hard-Probes/Weekly-HP-PWG-meeting
> > > > Zoom Meeting link:
> https://bnl.zoomgov.com/j/1611419615?pwd=VW1hNm43ZDd5d2EvK2R4aEJsQ2ZNZz09
> > [1]
> > > > [1]
> > > >
> > > > Meeting ID: 161 141 9615
> > > > Passcode: 744968
> > > >
> > > > Thank you
> > > > Barbara, Yi, Sooraj, Nihar
> > > >
> > > > On 2022-09-19 22:13, Nihar Sahoo via Star-hp-l wrote:
> > > > > Hello All,
> > > > >
> > > > > Last week we discussed a lot at the collaboration meeting, If
> > > > there is
> > > > > no urgent matter to discuss,  let's cancel this week's HP pwg
> > > > meeting.
> > > > > Have a great week.
> > > > >
> > > > > Thank you
> > > > > Barbara, Yi, Sooraj, and Nihar
> > > > > _______________________________________________
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