-- ZihengChen - 2016-10-12

Update

• Model comparison with cut can be found here
• fix bug in calculating pT_dimuon
• fix bug of tagging b in t2WbX top dark decay model

Introduction

Here is the first summary of model study of MuMuX analysis. The candidate models to explain 29 GeV MuMu resonance include low-mass Higgs, FCNC, Heavy b, and Dark interaction. Given each model at 8TeV and 13TeV, plots of key kinematics are presented here. Following is a list of models we have simulated in a pythia 8 based generator. More models are to be added if necessary.

CoM Energy	Models
8 TeV	Low-Mass Higgs: gg→ttX , gg→bbX FCNC: gg→tt→(cX)t FCNC: qq'→tb→(cX)b Heavy B: qq'→Bq''→(bX)q'' Dark Interaction: qq'→tq''→(WbX)q''
13TeV	Low-Mass Higgs: gg→ttX , gg→bbX FCNC: gg→tt→(cX)t FCNC: qq'→tb→(cX)b Heavy B: qq'→Bq''→(bX)q'' Dark Interaction: qq'→tq''→(WbX)q''

When generating events, the following mass parameter of heave B quark and unknown particle X are made. The mass property of B is inspired by the paper (add link), meanwhile mass property of X is indicated by our mumuX analysis (add link).

	Mass	Mass Width	Polarization
X	28.7 GeV	From Fit: 1.29 GeV Including Detector Influence: 1.9 GeV (used)	Scalar, Transverse, Longitudinal
B	175 GeV	3Lambda: 7.80 GeV (used) 2Lambda: 3.46 GeV 1Lambda: 0.86 GeV	Same as b

Muon Cut used in analysis is pT>25 GeV, |η|<2.1, 12GeV<M_µµ<70GeV. Here I have not apply this muon-kinematics filter to generated events. Therefore plots here are without muon phase cut. An update with muon filter will come soon. In terms of techniques, the Pythia 8 Based Event generator https://github.com/ZihengChen/Pythia8Generator takes a Physics card which specifies physics model and outputs

• root file -- contains an Event Tree of particles in each event. As well as some kinematics histograms for preview.
• lhe file -- contains hard process, input to CMSSW for detector simulation and ntupler.
• hepmc txt -- contains all particles info in each event.

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Events of 8 TeV pp Collision

Number of Events = 10,000

Red -- Longitudial Polarization, Blue -- Transverse Polarization, Black -- Scalar.

Low-Mass Higgs: gg→ttX

Low-Mass Higgs: gg→bbX

Dark Interaction: qq'→tq''→(WbX)q''

NCFC: gg→tt→(cX)t

NCFC: gg→tb→(cX)b

Heavy B: qq'→Bq''→(bX)q''