sPHENIX discussion of physics

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

Heavy Flavor Topical Group Meeting (2021/3/8)

https://indico.bnl.gov/event/10963/

Introduction - Jin (BNL)

Completion of the MDC1 samples!

Wei: Do we plan to make minbias samples?

Jin: Not for MDC1. The target is to check the signal efficiency.

Wei: With minbias, the efficiency will change. So, the point

      is to just see the peak?

Jin: For MDC1, yes. For BG studies, we also need the fastsim.

Zhaozhong: The day light saving time will start soon.

Jin: We will stick to the same time in ET for now.

MDC1 status & updates -  Cameron (LANL)

Added more options in KFParticle.

p.5:

Hideki: We will definitely need jet samples for 2021-2025.

Jin: Tracking is now stable. We are ready to produce jetty

      samples included Hijing embedded ones. We will also

      need to do fake jet studies.

Ming: What is the expected integ. lumi. for pp?

Jin: For the calorimeter trigger case, 62 pb-1.

Vertex performance with ACTS - Dan (Colorado)

Yen-Jie: You should also check the RMS and not just

      a Gaussian fit, since there is a large tail.

Hideki: Which sample are you running over?

Dan: I produced by myself.

Jin: The events are dominated by ccbar.

p.6:

Jin: You need to first check the DCA calculation deeper.

Yen-Jie: The DCA looks asymmetric for the light-jets.

      There must be a bug.

Jin: Which DCA is this?

Dan: The z direction.

Jin: Please also check the r-phi direction. We will follow

      up offline for the details.

Joe: Is the DCA straight out of the Svtx track objects?

Dan: No, I calculate separately.

Jin: The module is old and the code has changed a lot in

      the past 3 years. The DCA calculation in the analysis

      package needs to be revisited.

b-tag calibration - Sebastian (Iowa State)

p.4:

Hideki: Which jet flavor ID is used here? Truth parton or

      hadron?

Sebastian: Truth hadron.

Jin: What is the pt cut of jets?

Sebastian: 20 GeV.

Jin: For low pt, the decays can go out of the jet cone. Are

      all the track DCAs inside the jets? We may want to

      consider variable jet size.

Sebastian: Yes, DCAs are all inside the jets. Varying R

      would be tough for the calibration, etc.

Hideki: We at least have jets with various R. We should

      keep in close touch with the Jet TG, as they should be

      calibrating those jets. We may be able to study the

      R-dependence.

p.9:

Hideki: Are these from ttbar events?

Sebastian: Yes, but even without asking for ttbar, we can

      enhance b-jets by just requiring the leptons.

p.10:

Hideki: What do you calibrate here?

Sebastian: The efficiency, not the variables.

General:

Hideki: For electrons, we may need to develop ID working

      points by ourselves for the b-tag. The Upsilon TG is likely

      to develop only a very loose working point for their

      analysis.

Jin: Yes, but their code will be a good starting point.

Sebastian: Is DCA signed in sPHENIX?

Jin: Yes, but one needs to re-calculate to get the sign.

Jin: This is a very nice summary. We will post it on our twiki

      as a reference.

MDC1 studies - Sebastian (Iowa State)

p.3:

Jin: Large DCA tail in ccbar. Interesting... What is the

      structure seen here?

Cameron: Cuts will bias the distributions. We should

      check. (-> Some plots posted on MatterMost now)

Jin: There must be pre-selections cutting away the prompt

      D0's here.

Sebastian: I will add descriptions on the selections used

      on the slides.

Jin: The DCA distributions should behave as seen in the

      2017 note. Let's check the pre-selections. We should

      also check the HepMC record to make sure that c's

      are not coming from the b's.

p.5:

Jin: Which integrated luminosity?

Sebastian: 6M ccbar events. Mixing bbbar samples.

p.6:

Jin: The plot style looks ok, but there may be tiny tuning

     from Camelia for the Software & Computing Review.

     Please also update the D+ plot with the sPHENIX style.

MDC1 studies: Lambda_c - Sourav (Vanderbilt)

Cameron: Selection looks sensible. This is quite a

     challenging decay. We can see the peak with

     the truth matching (posted on MatterMost).

Jin: We can check whether the cuts are still tight or not.