Review: Search for a low mass dark photon radiated from a muon using 2018 Ultra Legacy data

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Help Replies key: answered; to be followed up; for discussion; to be done

Analysis documentation

  • CADI line:
  • Analysis notes: AN-21-100 (main documentation of the analysis)
  • CMS talk:
  • Contact: Yao Yao (contact), S. Mani Tripathi (supervisor)

Preapproval checklist

  • Blinding policy: The signal region is blinded.
  • Documentation: Analysis note, paper draft, CCLE, target journal.
  • Data sets: We follow the recommendations for UL analyses as summarized on PdmVRun2LegacyAnalysis.
  • Object experts:
Group Status Contact person Relevant links
Muons N/A Daniele Trocino  
Jets N/A Siqi Yuan  
  • Combine expert: Long Wang
  • StatComm questionnaire:
  • NanoAOD survey:
  • Issues in Run 2 data and corresponding recommendations:
    • HEM 15/16 failure (2018):

List of presentations

List of analysis notes

Before Pre-approval

Comments on presentations (physics)

Comment 001: About the dark photon mass that is chosen to be 0.5 GeV, have you sampled other dark photon mass to check if it will affect the kinematics of the events?

Answer: We tried lowering the dark photon mass to below 0.5 GeV in Madgraph but it soon reaches the precision limit of matrix element calculation and gives us a blowed up cross section. We've confirmed with Prof. David Curtin who wrote the Feynman rules that by changing the dark photon mass it should not change the kinematics of the events, because the dark photon mass is very small compared to the muons that are the other final state particles.

Comment 002: Why are there events that HCALEnergy/genDpEnergy is about 0.5 and ECALEnergy/genDpEnergy is also about 0.5?

Answer: These dark photons might start the pair production shower at the edge of ECAL, so part of its energy is deposited in ECAL and part in HCAL.

Comment 003: How many signal events are removed with the jet pT > 30 GeV selection?

Answer: About 85% of the signal events are removed with the jet pT > 30 GeV selection for all dark factors we sample.

Comment 004: Why HCALEnergy/genDpEnergy is centered at 1.3?

Answer: It is because of the intrinsic response ("e/h") of HCAL. The HCAL TDR quotes e/h = 1.4, i.e. a typical photon will induce 1.4 times as much signal as a pion in HCAL, on average.

Question2: test.

Answer2: test.

Question3: test.

Answer3: test.

Question4: test.

Answer4: test.

Comments on AN_v1 (editorial)

Comment: State the dark photon decaying in HCAL to make it clear.

Answer: Done.

Comment: Move the MVA study before the background estimation chapter, and state that you plan to use it (early on) might be better for the flow.

Answer: Done.

Jet object review

Comments by Person (Date) on AN v

Muon object review

Comments by Person (Date) on AN v

Combine cards review

Comments by Person (Date) on AN v

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Topic revision: r4 - 2022-11-22 - YaoYao
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