sPHENIX tracking discussion

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

Hi, Haiwang and Spencer

 

Thanks to Haiwang for making the poster for the topical group, and thanks to Spencer for bringing up the important point in the factorization of jet finding and b-jet tagging.

 

Currently, the HF-jet topical group is focusing on developing the first set of b-tagging algorithms, which include rejection of both light jets and charm jets. Therefore, at this moment, our simulation assumes perfect jet finding in Au+Au, which is not trivial at all. Since we recently established the two tagging algorithms (as discussed in this slides), we will move on to perform b-jet finding and tagging simultaneously in the next stage. At this moment, we only have updated performance plots for the b-tagging efficiency, but not yet on simultaneous b-tagging and b-jet finding. Nevertheless, we should point it out on the poster regarding this point:

 

1.       Good efficiency and purity of inclusive jet finding was found in sPHENIX proposal study, as discussed in Section 4.4 and 4.5 of arXiv:1501.06197. We can quote figure 4.12/4.14 on the poster to show the inclusive jet performance.

2.       The jet structure topical group plans to renew this study with updated and refined detector simulation. We should cite Rosi’s poster on the recent inclusive sPHENIX jet studies.

3.       In the conclusion/outlook section, we should mention right now we assumed factorization of jet finding and b-jet tagging and focused on developing tagging algorithms in full tracking simulation. The next stage of study will include both steps to study the interplay of jet finding and b-jet tagging.

 

In addition, a few more comments on the poster:

 

·       Abstract: “we studies” -> “we study”

·       sPHENIX Tracking System: Nice event displays. Meanwhile, please add simple description of tracking system detector used in sPHENIX tracking

·       Impact Parameter Method:

o   “PYTHIA 8 20 GeV jets for jet only” -> “p+p jetty event sample simulated in PYTHIA8 hard-QCD mode”

o   “20 GeV jets” -> “jets with minimal pT of 20 GeV”

o   “Tracker: Cylindrical MAPS(3) + INTT(4) + TPC” -> Geant4 used to simulate response of tracking detector

o   “Calculate b-jet purity vs. tagging efficiency based on PYTHIA 8” -> “Calculate b-jet purity vs. tagging efficiency as shown below”

o   The HIJING-embedded rejection curve for three-track large DCA method (blue curve) is missing low efficiency part?

o   Please remove the second plot on the right column. These four panels are right now too busy and is hard to read.

·       Secondary Vertex Method:

o   “Similar after process from efficiency vs. cut” -> “Calculate b-jet purity vs. tagging efficiency as shown below”

o   “full reconstruction done for jet only and jet+HIJING” -> “full tracking reconstruction done for p+p and central Au+Au events”

 

Cheers

 

Jin

 

 

 

______________________________

 

Jin HUANG, Ph. D.

 

Associate Physicist

Brookhaven National Laboratory

Physics Department, Bldg 510 C

Upton, NY 11973-5000

 

Office: 631-344-5898

Cell:   757-604-9946

______________________________

 

From: sphenix-tracking-l-bounces AT lists.bnl.gov [mailto:sphenix-tracking-l-bounces AT lists.bnl.gov] On Behalf Of Spencer Klein
Sent: Tuesday, January 31, 2017 12:41 PM
To: Haiwang Yu <yuhw.pku AT gmail.com>; sphenix-hf-jets-l AT lists.bnl.gov; sphenix-tracking-l AT lists.bnl.gov
Cc: srklein AT llb.gov
Subject: Re: [Sphenix-tracking-l] QM poster: b-jet tagging study

 

Haiwang:

I have the same comment on this poster that I did on the pre-proposal. 

The poster has a lot of material about finding b hadrons, but not much about finding an associated jet once the b-hadron is found.    We see from STAR that finding jets at RHIC is very tough, and it is even tougher to extract useful information, due to a variety of causes.  The underlying event, with its underlying azimuthal variation due to anisotropic flow is not easy to remove.   In the case of b jets, we also need to consider the effect of overlapping b-hadrons + non-b jets and also misidentified charm (in either a charm jet, or coincident background).  And, since jets in AA are modified from those in pp, one should not do a naive apples-to-apples comparison of their extracted jets.

Spencer

 

On 1/31/17 09:33, Haiwang Yu wrote:

Dear all,

 

I uploaded a QM17 poster draft for the b-jet tagging study.

https://indico.bnl.gov/getFile.py/access?contribId=18&resId=0&materialId=slides&confId=2794

 

Comments and suggestions will be very appreciated.

 

Cheers,

Haiwang

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