sPHENIX discussion of physics

[Cameron Thomas Dean <cameron.dean AT cern.ch>]

Dear all,

Here are the minutes of this weeks quarkonia and heavy flavor meeting. The meeting agenda can be found at: https://indico.bnl.gov/event/16509/

 

Introduction

Cameron - Please let the convenors know if you have any production requests for MDC2 and we'll add them to our request list. Requests can be seen here: https://wiki.bnl.gov/sPHENIX/index.php?title=MDC2_2022#Requested_Samples

 

RBRC workshop follow-up discussion

Jin - For the latest production, do we have full events?

Cameron - Currently, we only have truth information RBRC Cameron - Does anyone have any thoughts on the baryon/meson ratio in b-hadron decays?

Jin - The background rejection is a big worry, especially at low PT. We will need lots of simulations for this, we could start with a FastSim

Joe - What can we do about the PID requirements?

Cameron - It's a challenge but we can cut on the mass of intermediate products such as D0 and Lambda_c, similar techniques were employed at CMS for their b-hadron in PbPb analysis

Dennis - What do our charmonium prospects look like? Do we need to start with higher pT events?

Jin on HF jets - D0 jets are good starting points, it's cleaner and we can go to very low pT.

Dennis - Bill asked a question on radiative decays, can we do something with soft (~100 MeV) photons?

Jin - This will be close to the EMCal noise level

Jin to Dennis - Did we reach a consensus on a proceedings document on the workshop?

Dennis - We're reaching out to some speakers, we expect to have one and will arrange a timeline for it.

 

EvtGen

Slide 5

Dennis on the branching fraction - There should be some statistical uncertainty on these values.

Zhaozhong - Yes, the BF is calculated from the number of exclusive decays with respect to the total number of generated D0

 

Slide 8

Tim - You can change the Pythia decay table to get the right BF, This was done in PHENIX.

Jin - We can leave Pythia as is for now. We demonstrated that the decayer is working but we will move to EvtGen for the final production

 

Slide 13 -

Jin on changing from HepMC3 to HepMC2 - We should confirm this doesn't bring in any unexpected changes

Cameron - We should confirm this. sPHENIX and F4A use HepMC2 and we don't plan to change it as it's only a reader.

Jin - The QA module should be added to coresoftware to have as a general tool Preliminary code can be submitted for Jenkins checks already, this will help development in the long run. Zhaozhong - Do we want EvtGen for MDC2?

Jin - Yes, if ready

 

Jin - We should zoom into the D0 peak to see if we're missing photons in our truth record. Our truth compression can drop very low-energy photons which can impact the reconstructed mass.

 

AOB

Ming - Can we work on inclusive decays yet

Cameron - We've confirmed that the new setup works for charm and pythia6. We only have truth info for now and will need to run them through the full simulation.

Ming - Does the recent G4 decayer problem affected the 2017 MVTX proposal b-jet study?

Jin - The Geant4 decayer issue here is very recent starting G4.10.7. As far as we're aware, our b-jet reconstruction in sPH-HF-2017-001 is done correctly.