Analysis of 3 Lepton + Missing Et final state

Excited Electro/Neutrino

Event Generation

nu* and e* via gauge interaction was generated in several steps. at first events were generated using Calchep for different colour of the incoming parton. The two different sets of events were mixed according to their production cross section by function named event_mixer inside calchep to give final set of unweighted events in LesHouches event format.

i. Production of nu* via gauge interaction

beam energy (Gev) mass of nu*(Gev) cross-section error in x-section
3500 300 158 + 71.7 1.09 E-01 pb
500    
750    
5000 300 158 + 71.7 1.09 E-01 pb
500    
750    
7000 300 158 + 71.7 1.09 E-01 pb
500    
750    

ii. Production of nu* via contact interaction

beam energy (Gev) mass of nu*(Gev) cross-section error in x-section
3500 300 158 + 71.7 1.09 E-01 pb
500    
750    
5000 300 158 + 71.7 1.09 E-01 pb
500    
750    
7000 300 158 + 71.7 1.09 E-01 pb
500    
750    

iii. Production of e* via gauge interaction

beam energy (Gev) mass of e*(Gev) cross-section error in x-section
3500 300 158 + 71.7 1.09 E-01 pb
500    
750    
5000 300 158 + 71.7 1.09 E-01 pb
500    
750    
7000 300 158 + 71.7 1.09 E-01 pb
500    
750    

iv. Production of e* via contact interaction

beam energy (Gev) mass of e*(Gev) cross-section (pb)
3500 200 94.63
300 72.04
500 38.59
750 17.54
5000 200 235.3
300 195.6
500 123.0
750 94.63
7000 200 529.1
300 459.0
500 329.9
750 218.4

-- PiyaliBanerjee - 09 Oct 2009

Heavy Quark

We perform a search for fourth generation heavy quark with heavy quark decaying to W boson and b. The W boson has a branching ratio of 80% to decay to di-jets while it has 20% branching ratio to decay to lepton and neutrino. We assume that heavy quark only couples to first generation quarks.

i. Event Generation

We used Comphep () to generate our process. We generate two different matrix element corresponding to two different Feynman graph for heavy quark T. We analogously generate two more matrix element corresponding to T' ( anti quark). In one graph we have 2->2 where qq'->q''T where T->Wb. Another is 2->3 process where qg->q''Tb where T->Wb. We have similarly 2->2 and 2-> 3 for T'. The q'' in the final state are light quarks which hadronizes to produce light quark jets. We thus generate events corresponding to the four diagrams via comphep at the parton level without allowing W to decay. We set the C.O.M energy to 10 TeV and we allow the Q-scale to be heavy quark mass which after
several studies is fixed to 300 GeV. Comphep generated set of events for different flavour of initial parton and anti parton. We allowed these different sets of events to mix according to their cross section to get the final event set. This resulting event set was allowed through cpyth () an interface to pythia to allow hadronization of the final state quarks. At this stage we also allowed the W to decay via all the decay modes. The events file obtained after passing through pythia is in the LesHouches event file format. These events were then passed to Atlfast, a fast simulation package to generate the Atals detector effects on our physics events. The output of Atlfast can be simple ntuple or complex containers stored as AOD file. The
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