Reconstructing Bottom mesons using displaced vertices from semi-leptonic decays

Abstract

Precise determination of heavy flavor production cross-sections at LHC energies will be of primary importance. The produced heavy quarks are expected to be sensitive probes of parton energy loss in the medium formed in heavy-ion collisions. Through the measurement of charm and bottom suppression in Pb + Pb with respect to p + p, we hope to obtain insight into the color-charge and quark mass dependence of the energy loss mechanism. The ALICE experiment with its large acceptance is well suited to investigate the intermediate transverse momentum spectrum of heavy flavor mesons where these energy loss effects are expected to be visible. ALICE has very good electron PID capabilities over a large kinematic range using Time Projection Chamber (TPC), Transition Radiation Detector (TRD) and the Electromagnetic Calorimeter (EMCal). In addition the EMCal, to be installed for the Pb + Pb runs, is planned to allow efficient triggering on high-pT jets. We first introduce the EMCal project and an overview of detector specifications. Then we introduce a method developed to select preferentially electrons from heavy flavor decays by reconstructing displaced secondary vertices. The strategy is to reconstruct displaced vertices from semi-leptonic heavy flavor meson decays using the excellent spatial resolution of the Inner Tracking System (ITS). We show preliminary results of an efficiency study from charm vs. bottom vertices.