20 likes | 134 Vues
Search for Excited Electrons. Ahmed ABDELALIM, Alain BLONDEL, Bertrand MARTIN. In compositeness models, quarks and leptons are assumed to be bound states of “ preons ” made of three fermions or a fermion and a boson. Predict a large spectrum of excited states
E N D
Search for Excited Electrons Ahmed ABDELALIM, Alain BLONDEL, Bertrand MARTIN • In compositeness models, quarks and leptons are assumed to be bound states of “preons” made of three fermions or a fermion and a boson. Predict a large spectrum of excited states • Study singly produced e* via Contact Interaction (CI) and decaying via Gauge Mediated (GM) decay. • Three GM decay modes: • ν + W 2 j + or l + • e + γ : most promising channel (high branching ratio and low SM background) • e + Z e +2 j or e + 2 l • Final state : 2e+ γ • Model with 2 parameters : excited electron mass me* and compositeness scale Λ. e e* e e* q q q q Single e* prod. Cross section
Previous Limits : • LEP, HERA : me* > 300 GeV • CDF : me* > 879 GeVfor Λ= me* • DØ : me*> 796 GeVfor Λ = me* • Backgrounds : • Physics : Z+ γ • Jets faking e/γ:Z+Jet, W+ γ, W+Jet, diboson, QCD ....(will be included later) Excl. 95% CL me*=1TeV, Λ= 5TeV Reco. meeγ Reco. meγ