sPHENIX discussion of physics

[Hideki Okawa <Hideki.Okawa AT cern.ch>]

Heavy Flavor Topical Group Meeting (2021/7/12)

https://indico.bnl.gov/event/12395/

Introduction - Jin

We may possibly have joint meetings with the Upsilon TG

in the near future. We invited Weihu Ma for the electron ID

talk as one of the first steps.

Vertex Check from MDC1 - Sanghoon Lim (notes by Jin)

Sanghoon: PHActsInitialVertexFinder used to rerun the ACTS

   vertex finder
Cameron: final vertex finder under beta testing.
Dan: trying final ACTS vertex fidner but observed weird behavior.
Jin to Dan: were you running with MVTX hit matching requirement

   on the tracks?
Dan: no. Plan to add the cut and update to the TG in the coming

   meetings

Sanghoon: also observed low MVTX matching eff.
Jin: current tracking required track seeding of three layers, which

   leads to suppression of the previous 1 and 2 MVTX hit tracks.
Cameron: black curve is TPC alone, which relates to a similar

   observation in KFparticle study
Jin: from the daily check, the MVTX matching efficiency appears

   high at pT>1 GeV/c: https://nbviewer.jupyter.org/github/sPHENIX-Collaboration/QA-gallery/blob/jenkins-sPHENIX-test-tracking-low-occupancy-qa-1254-test-tracking_Event1000_Sum15/QA-tracking.ipynb#Number-of-clusters-per-tracker
Xin: Is there any pile up?
Jin: no. Current tracking can not handle pp pile up yet
Xin: what is the vertex distribution?
Jin: 8cm gaussian distribution: https://github.com/sPHENIX-Collaboration/MDC1/blob/main/submit/HF_pp200_signal/rundir/Fun4All_G4_HF_pp_signal.C#L225

TODO [Sanghoon]: Update slide 2 plot to use 10cm vertex cut

   to avoid bias by outside MVTX vertex acceptance

Electron ID - Weihu Ma

p.5

Jin: The rejection performance visibly differs depending

  on the charge sign, in particular p and anti-p. It is

  better to plot them separately. Anti-p requires dedicated

  studies.

Cameron: The difference between K+ and K- is also large.

p.6

Hideki: Why x-errors are so large in the upper right plot?

Weihu: The plot zooms in a narrow range, so the errors

   are not as large as they seem. Also, there are correlations

   between each point, so there is overlap among them.

p.7

Cameron: The drop in efficiency around |eta|~1 may be

   due the current treatment of the constant B field

   assumption. Please check whether this trend stays in

   MDC2.

Hideki: We should think about whether we need to develop

   our own working points in HF analyses.

Jin: It is good to have a formalized analysis module in order

   to implement momentum-dependent cut, etc.

Jin: Do we have sufficient calo information in KFParticle?

Cameron: We have 3x3 and 5x5 calo clusters in KFParticle,

   so we can easily check the cuts for HF analyses and

   compare with the Upsilon performance.

Jin: Do you apply position-dependent energy correction on

   the 3x3 clusters? How about in KFParticle?

Weihu: Yes, I do in my plots.

Cameron: It is not considered in KFParticle.

Jin: We can borrow the implementation from the Upsilon

   team.

Sebastian: Are we ok with applying just flat cuts? Have we

  looked at jet samples?

Hideki: We don't yet have jet samples.

Jin: The electron clusters are much smaller than jet cone

   size, but it is indeed important to have dedicated studies.