Investigating the Electron Reconstruction Efficiency at the LHCb

Abstract: An exploratory investigation of the electron reconstruction efficiencyat the LHCb is presented. The study is done through simulations ofparticle interaction with the full LHCb detector setup, both by firingsingle particles into the detector and by generating the decay of Bmesons into J/psi K, where the J/psi decays into dileptons. PreviousLHCb analysis of the decay has shown a large yield difference betweenthe number of electron versus muon final states, around a factor offour. The kinematical dependence on the reconstruction efficiency ofthe leptons is studied and found to be non-discriminatory. Theelectronic channel loss of yield is compared to the muonic channel withthe purpose of finding in which reconstruction and selection steps theyield discrepancy factor originates. A total factor of 1.8 is found,which combined with the L0 trigger factor of 2 makes the resultcomparable to the observed factor. A large loss of yield from ageometrical selection, which requires electrons to be in the acceptanceof the electromagnetic calorimeter or in the pre-shower detector,triggers a study of the performance of electrons failing thisrequirement. The performance is determined by looking at how well theparticles are identified, using both LHCb data and simulations. Thefailing electrons are found to perform well, therefore the requirementis considered superfluous and avoiding it would increase the electronfinal state yield with around 14.5%.