Measurement of muon tagged open heavy flavor production in Pb+Pb collisions at 2.76 TeV with ATLAS

Bottom quark is a very important probe to study the hot, dense medium produced in the heavy ion collisions. Bottom quark is produced at the relatively early stage of the nucleus-nucleus collisions and may have a small gluon radiation due to a suppression of small angle gluon radiation `dead cone effect’. Because the heavy mass of b-hadrons, muons from semi-leptonic b-hadron decays tend to have larger angle with respect to the jet axis. This information can be used to tag b-jets. Specifically, the transverse momentum of the muon with respect to the b-jet axis, pT^{rel}, is used to differentiate b-jets from the background charm and light quark jets. In this talk, we present the b-jet suppression R_CP, which is defined as the ratio of the average N_coll scaled yield in central collisions to that in peripheral collisions (60-80%), as a function of the muon momentum, jet momentum and the number of participants average N_part in Pb+Pb collisions at 2.76 TeV. The result is also compared with the inclusive heavy flavor suppression, which was obtained by studying single muons decayed semi-leptonically from the from the b- and c-quark containing hadrons.