sPHENIX discussion of physics

["Huang, Jin" <jhuang AT bnl.gov>]

Introduction - Hideki Okawa

 

MDC1 plan:

Sebastian: do plan to produce an AuAu background with HIJING simulation?

Jin: Background is the most challenging part. Concern AuAu simulation too slow to match background stat. So suggest follow the sPH-HF-2017-02 note and use fast simulation to update the AuAu background with the updated tracking. There was a validation plot in sPH-HF-2017-02 to check fast simulation against full simulation

Hideki: how ATLAS handle the background study? 

Sebastian: ATLAS simulated PYTHIA and PYTHIA embedding to real data

 

 

HF tools - Cameron Dean

 

Hideki: When MB simulation would be submitted? 

Cameron: expect a fix into the production build (acts was not handling low multiplicity events), they should be ready to go

 

 

D0 update - Hansheng Li

 

Jin: it is interesting to notice the asymmetric tail on slide 3 

Cameron/Wei/Jin: suggest check 2D plots: 

• D0 Mass vs D0 pT
• p_reco/p_truth vs p_truth for the pion and kaon tracks. 

 

Slide 5: b->D0 has a significant DCA peak at zero

Cameron: Charm is produced while a b production? 

Jin: This may be possible as MPI is on, but the cross-section at RHIC should be small

Cameron: ACTS vertex to false in this analysis, and the code could have grabbed secondary vertex in the truth container and used as primary vertex

Jin: there is a deterministic way to extract the primary vertex via HepMC::FourVector& PHHepMCGenEvent::get_collision_vertex()

 

Wei: It will be very useful to have an ancestry trace to quarks to validate the quark origin of the b->D0?

Cameron: latest version should have that. 

 

 

Slide 6: 

Cameron : TrackIP Chi2>1 FD X2 >80 push the resonance to be displaced

 

Xin: what is the decay vol. setting in Pythia? 

Jin: currently not set [ https://github.com/sPHENIX-Collaboration/MDC1/blob/main/submit/HF_pp200_signal/rundir/phpythia8_HF_MDC1.cfg ]

Xin: suggest to hand long-lived particles to G4 propagation and it is great Fun4All has the built-in Pythia6 decayer

Hideki: How STAR handled it? 

Xin: Via embedding. 

 

TODO by Jin and Cameron: work with ACTS developer on the vertex finding algorithm for HF MDC1. 

 

 

D_s update - Zhaozhong Shi

 

Jin: what was the difference between slides 3 and 4 in cuts? 

Zhaozhong: matching truth PID, vertex matching cuts. 

 

Jin: is there a way to apply a cut on the KFParticle output nutple that requires a parent to exclusively decay to a final state? 

Cameron: Currently no direct trick. 

Jin: for Zhaozhong, a quick fix is to follow hansheng's example to cut on inv. mass of the truth momentum matching PDG mass. 

Jin: decay finder is a cleaner solution. And it would be great if the decay finder could output a DST object, so a user analysis module could match the finder result to the events.  

 

Xin: what is the low pT reach for the Ds reco?

Zhaozhong: CMS D_s reached down to 3GeV/c, B_s can reach zero. Not yet looked carefully at sPHENIX. 

Jin: might need dedicated D_s signal filtered simulation to build sufficient statistics on the pT acceptance scan

 

 

 

______________________________

 

Jin HUANG

 

Physicist, Ph.D.

Brookhaven National Laboratory

Physics Department, Bldg 510 C

Upton, NY 11973-5000

 

Office: 631-344-5898

Cell:   757-604-9946

______________________________

 

From: Huang, Jin
Sent: Friday, May 14, 2021 1:33 PM
To: sphenix-hf-jets-l AT lists.bnl.gov
Cc: sphenix-physics-l AT lists.bnl.gov; sphenix-maps-l AT lists.bnl.gov
Subject: [Monday 8PM EDT] bi-weekly heavy flavor topical group meeting

 

Hi Everyone,

 

This is a reminder that we will have our next HF topical group meeting on May 17 Monday 8PM EDT.  

 

On the agenda will follow up many of the work on MDC1 analysis:

 

• Introduction – co-conveners
• KFParticle and MDC1 updates - Cameron Dean
• DCA for Prompt and non-prompt D0 – Han-sheng Li
• D_s check with truth tagging – Zhaozhong Shi

 

Please join us via

 

• Indico: https://indico.bnl.gov/event/11886/
• ZOOM connection: https://bnl.zoomgov.com/j/1613938007?pwd=QjYzUnpYQ2xNZWZLSy9qd3Z4dFpzZz09

 

We look forward to talking to you all at the meeting.

 

Best regards,

 

Hideki & Jin