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[Star-hp-l] Notes for PWGC preview (11/04/2022): 3D jet substructure measurements in pp collisions at 200 GeV
- From: "Ma, Rongrong" <marr AT bnl.gov>
- To: STAR Papers Discussion List <starpapers-l AT lists.bnl.gov>, "STAR PWG Convener List" <star-pwgc-l AT lists.bnl.gov>, STAR HardProbes PWG <Star-hp-l AT lists.bnl.gov>
- Subject: [Star-hp-l] Notes for PWGC preview (11/04/2022): 3D jet substructure measurements in pp collisions at 200 GeV
- Date: Fri, 4 Nov 2022 20:01:10 +0000
Date: 11/04/2022
Participants: Monika Robotkova, Raghav Kunnawalkam Elayavalli, Joern Putschke, Helen Caines, Daniel Cebra, Nihar Sahoo, Barbara Trzeciak, Sooraj Radhakrishnan, Qinghua Xu, Xiaoxuan Chu, Prithwish Tribedy, Subhash Singha, Jiangyong Jia, Xiaofeng Luo, Takafumi
Niida, Rongrong Ma
Title: 3D jet substructure measurements in pp collisions at 200 GeV
PAs: Monika Robotkova, Georgi Ponimatkin, Jana Bielchikova, Raghav Kunnawalkam Elayavalli, Helen Caines, Joern Putschke
Target journal: PRL and PRD
Proposal page: https://drupal.star.bnl.gov/STAR/blog/elayavalli/run12-iterative-substructure-1st-2nd-and-3rd-splittings-fully-unfolded-zgrg-distribu
Presentation: SLIDES
The PWGC panel previewed a paper from HP PWG. The panel found that analysis is mature and the paper should move forward, and the target journals are appropriate. The following points were discussed.
(Q: question, A: answer, C: comment)
s3
Q: is it true that different splittings are separated so much in space?
A: this cartoon is for illustrative purpose. It does not correspond to reality, where splittings happen within a very short time scale.
Q: is it true that different splittings are separated so much in space?
A: this cartoon is for illustrative purpose. It does not correspond to reality, where splittings happen within a very short time scale.
s11
Q: how do you classify first, second and third splits?
A: they are classified based on the SoftDrop algorithm by following the hardest branch.
Q: how do you know they correspond to first, second and third splits in a parton shower?
A: these definitions are operational, and depend on the specific jet finding and reclustering algorithms. It is not easy to connect them to the parton splitting, which is why we intentional use jets, instead of partons, in the paper.
Q: how do you classify first, second and third splits?
A: they are classified based on the SoftDrop algorithm by following the hardest branch.
Q: how do you know they correspond to first, second and third splits in a parton shower?
A: these definitions are operational, and depend on the specific jet finding and reclustering algorithms. It is not easy to connect them to the parton splitting, which is why we intentional use jets, instead of partons, in the paper.
s12
Q: we know that the jet patch trigger biases towards gluon jets. Is this effect accounted for?
A: yes, this effect is accounted for when correcting the jet trigger efficiency based on event generators. Jet substructure shapes for particle-level jets that do not satisfy the jet patch trigger are used. Furthermore, we restrict our measurements to be above 20 GeV/c, where the trigger bias on the neutral energy fraction is seen to be small and the triggered jet sample is close to the inclusive jet sample.
C: it will be useful to compare the jet substructure distributions between quark and gluon jets, and between jets that pass vs. do not pass the jet patch trigger in PYTHIA.
Q: we know that the jet patch trigger biases towards gluon jets. Is this effect accounted for?
A: yes, this effect is accounted for when correcting the jet trigger efficiency based on event generators. Jet substructure shapes for particle-level jets that do not satisfy the jet patch trigger are used. Furthermore, we restrict our measurements to be above 20 GeV/c, where the trigger bias on the neutral energy fraction is seen to be small and the triggered jet sample is close to the inclusive jet sample.
C: it will be useful to compare the jet substructure distributions between quark and gluon jets, and between jets that pass vs. do not pass the jet patch trigger in PYTHIA.
s16
C: usage of jargons in the title and abstract will make it less accessible to the wider community, which does not meet the PRL criteria.
C: it is suggested not to use works like first, novel, for PRL since by default all manuscripts submitted to PRL are new.
A: we will work on improving upon this.
C: usage of jargons in the title and abstract will make it less accessible to the wider community, which does not meet the PRL criteria.
C: it is suggested not to use works like first, novel, for PRL since by default all manuscripts submitted to PRL are new.
A: we will work on improving upon this.
s19
Q: do you always find three splits for each jet? Do you use the same jets for different splits?
A: no, there could be jets with one, two, three or more splits. These distributions are normalized by the total number of splits for shape comparison, and the number of jets contributing to different distributions are different. There are more jets for first split than third split.
Q: can these measurements be compared to theoretical calculations?
A: we reached out to a few theorists and they mentioned that they can calculate zg and Rg at the first split. When it comes second split, non-perturbative effects become large due to the decrease of scale (pT*Rg), and therefore calculations become complicated. Hopefully, publication of these results will prompt theorists to seriously quantify the non-perturbative effects.
Q: do you always find three splits for each jet? Do you use the same jets for different splits?
A: no, there could be jets with one, two, three or more splits. These distributions are normalized by the total number of splits for shape comparison, and the number of jets contributing to different distributions are different. There are more jets for first split than third split.
Q: can these measurements be compared to theoretical calculations?
A: we reached out to a few theorists and they mentioned that they can calculate zg and Rg at the first split. When it comes second split, non-perturbative effects become large due to the decrease of scale (pT*Rg), and therefore calculations become complicated. Hopefully, publication of these results will prompt theorists to seriously quantify the non-perturbative effects.
s20
C: one can not say ".. measurements show a week dependence on the jet pT and resolution parameters ..." since these dependences are not shown in the PRL figures.
A: we will remove this statement.
C: one can not say ".. measurements show a week dependence on the jet pT and resolution parameters ..." since these dependences are not shown in the PRL figures.
A: we will remove this statement.
s28
Q: it sounds inconsistent that there is difference in zg for the same jet vs. initiator pT (which is essentially comparing jets of different pT), but no difference in zg for different jet pT (s27).
A: there could be subtle difference in jet vs. initiator pT, but we see your point. We will work on clarifying this point by pointing out the cause of the difference in zg seen in jet vs. initiator pT.
Q: it sounds inconsistent that there is difference in zg for the same jet vs. initiator pT (which is essentially comparing jets of different pT), but no difference in zg for different jet pT (s27).
A: there could be subtle difference in jet vs. initiator pT, but we see your point. We will work on clarifying this point by pointing out the cause of the difference in zg seen in jet vs. initiator pT.
s30
Q: is the narrowing of the Rg distribution with increasing splitting number due to the SoftDrop algorithm used?
A: it is true that these distributions are affected by the specific jet finding and reclustering algorithms used, which is the case for all jet measurements. We will make it very clear in the paper. Of course, these are not random choices of algorithms. The SoftDrop authors have done extensive studies that their results are consistent with pQCD calculations at high energy, which makes it even more interesting to do such measurements at RHIC energy.
Q: the HERWIG curves are very hard to see.
A: we will work on this. Maybe add a ratio plot.
Q: is the narrowing of the Rg distribution with increasing splitting number due to the SoftDrop algorithm used?
A: it is true that these distributions are affected by the specific jet finding and reclustering algorithms used, which is the case for all jet measurements. We will make it very clear in the paper. Of course, these are not random choices of algorithms. The SoftDrop authors have done extensive studies that their results are consistent with pQCD calculations at high energy, which makes it even more interesting to do such measurements at RHIC energy.
Q: the HERWIG curves are very hard to see.
A: we will work on this. Maybe add a ratio plot.
- [Star-hp-l] Notes for PWGC preview (11/04/2022): 3D jet substructure measurements in pp collisions at 200 GeV, Ma, Rongrong, 11/04/2022
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