sPHENIX discussion of physics

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

 

Announcement

• Cameron and Chris started production of the HF charm pp and pp with the full pile up. Thanks to much work and validation from the TG since the MDC2 workfest. We will announce data location and sample analysis code once available. 
• Tony expects to release the first set of tracking codes allowing analyzing streaming data in pp, which would allow us to use a large MB pp sample from MDC2 in addition to preparing for the Run24 pp data reconstruction. 

 

b-jet tagging using JetVLAD

 

Summary: invited talk of Raghav Kunnawalkam Elayavalli, introducing their recent papers on ML HF-jet tagging at the RHIC energy

 

Slide 3: 

Raghav: Jets are tagged based on the initiator parton

Jin: sPHENIX b-jet definition is slightly different, jet with a b-quark in it, which includes the g->bb splitting. 

Cameron: Perhaps of interest, ATLAS has a measurement of g->bbbar splitting using jet substructure techniques: https://inspirehep.net/literature/1711114 

 

Slide 4: 

Jin: DCA lineshape on top of resolution would be an important challenge to b-jet tagging as a tail from light particle track leak into the b track region. 

Jin: we also found that sigmalized DCA is very useful in b-jet tagging. 

 

 

Slide 6: 

Raghav: NetVLAD reduction dimension with variable input dimension and fixed-sized output vector. There are two variable parameters. This tool was initially applied to AI imaging processing

Hideki: does permutation variation matter? 

Raghav: using the default ordering from FastJet (pT ordered). However, tests show permutation does not change the result for NetVLAD as on slide 26

 

 

Discussion: 

Jin: in general, applying the 2D DCA lineshape smearing to this sample would be a very useful way to perform fast-smearing projection for sPHENIX data. Happy to share our lineshape used in sPH-HF-2017-002

Jin: in sPHENIX b-tagging, we also found the following feature is very useful: sigmalized DCA, wider cone to capture HF decay tracks, secondary vertex, and vertex mass

 

Ming: would the ML approach apply to KFParticle reco result within jets, 

Jin: if we look for exclusive HF channels, BR would make the overall efficiency very small. Another approach is to use a leptonic tagger that captures ~20% of BR.  

Cameron: it is also possible to run KFparticle in inclusive 2nd vertex tagging mode, which can be very useful like the secondary vertex tagger developed by Sanghoon during sPH-HF-2017-001 

 

 

 

______________________________

 

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: sPHENIX-HF-jets-l <sphenix-hf-jets-l-bounces AT lists.bnl.gov> On Behalf Of Marzia Rosati via sPHENIX-HF-jets-l
Sent: Wednesday, November 10, 2021 1:15 AM
To: sphenix-hf-jets-l AT lists.bnl.gov
Subject: [Sphenix-hf-jets-l] Reminder HF/Quarkonium TG meeting is today at 9:30AM ET

 

Reminder the joint joint HF/Quarkonium TG meeting is today November 10 (Wed) at 9:30AM ET
Please join us via:
Indico: https://indico.bnl.gov/event/13753/
Zoom:https://bnl.zoomgov.com/j/1613938007?pwd=QjYzUnpYQ2xNZWZLSy9qd3Z4dFpzZz09

We look forward to meeting you then.

Best regards,
Jin, Hideki, Tony and Marzia