wiki:Korea2017-01-CMS-EXO16-022

The first MadAnalysis 5 workshop on LHC recasting @ Korea

Analysis 1: CMS-EXO-16-022

Students Chang Jung, Kang Dayoung, Wu Peiwen, Yang Seungjin
Supervisor(s) Sam Bein, Jory Sonneveld

1. Analysis summary

Long lived particles

A search for new long-lived particles decaying to electrons and muons is presented using data from proton-proton collisions produced in 2015 by the LHC. Events are selected with an electron and muon that both have transverse impact parameter values between 200 μm and 10 cm. Since no significant excess is observed, limits are set on the Displaced Supersymmetry model, with pair production of top squarks decaying into an e-μ final state via R-parity-violating interactions. The results are the most restrictive to date on this model.

2. Analysis global information

Pythia generator information:

https://github.com/cms-sw/genproductions/blob/master/python/ThirteenTeV/DisplacedSUSY_stopToBottom_M_900_1mm_TuneCUETP8M1_13TeV_pythia8_cff.py

3. Selection description

3.1 Trigger selection

The events in the search sample are collected by a dedicated targets displaced e-mu pairs.

Muons : with momentum perpendicular to the beam axis, pT> 38 GeV Electrons : electromagnetic calorimeter with pT > 38 Gev

To increase the acceptance,

Muons : no cuts on the impact parameter or matching to a primary vertex are required for the muon leg of the trigger Electrons : no tracking information is used in the electron leg of the trigger.

PS: This part cannot usually be described by the fast-simulation of detector.

3.2 Object definition

  • Electrons
    • |eta| < 2.4
    • pT > 42 GeV
  • Muons
    • |eta| <2.4
    • pT > 40 GeV
  • ΔR(e,mu) > 0.5
  • Jets
    • |eta| < 2.4
    • pT > 30 GeV
    • medium CSV b-tag (>0.8) (at least one of the two)

Explained here how the objects are defined.

3.3 Cut-flow chart

3.4 Definition of exotic observables

Like SUSY transverse observable. Notice that classical MT2 & MT2W are encoded within the MadAnalysis framework.

3. Detector simulation

Can we use the last release of the Delphes package with the CMS/ATLAS MA5tune-card? or do need to improve the simulation?

4. Validation material

4.1 Monte-Carlo samples

  • LO/NLO? LO
  • Model used:
  • MC generator program (name + version): Pythia 8
  • Shower program (name + version):
  • Tune of Pythia:
  • PDF set:
  • ME/PS merging????

4.2 Reference plots / cut-flows

4. Validation results

5. Reinterpretation (optional)

6. Questions / issues

7. Contact information

  • J. Chang [mail: lovejesus99wwjd@gmail.com]
  • D.Kang [mail: dayou17@gmail.com]
  • P.Wu [mail: peiwen.wu123@gmail.co]
  • S.Yang [mail: slowmoyang@gmail.com]
Last modified 3 years ago Last modified on 08/26/17 18:22:28

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