Measurements of the Z boson in lepton pair decays in heavy ion collisions at ATLAS

Measurement of Z boson production in Pb + Pb collisions at √ s NN = 2.76 TeV with the ATLAS detector, obtained for approximately 0.15 nb − 1 data collected in 2011 LHC run is presented. The Z bosons are reconstructed in their di-electron and di-muon decay channels. The results from both channels are found to be consistent and hence combined. Within the statistical and systematic uncertainties, the per-event Z boson yield integrated over rapidity | y Z | < 2.5, is found to be proportional to the number of binary collisions calculated by the Glauber model. The elliptic flow coe ffi cient of the Z boson azimuthal distribution with respect to the event plane is found to be consistent with zero.