A search for Z bosons in the mu^+mu^- decay channel has been performed in PbPb collisions at a nucleon-nucleon centre of mass energy = 2.76 TeV with the CMS detector at the LHC, in a 7.2 inverse microbarn data sample. The number of opposite-sign muon pairs observed in the 60--120 GeV/c^2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of (33.8 +/- 5.5 (stat) +/- 4.4 (syst)) 10^{-8}, in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.
CMS Collaboration, Quertenmont, L., Chatrchyan, S., Basegmez, S., Bruno, G., Caudron, J., Ceard, L., Cortina Gil, E., de Favereau de Jeneret, J., Delaere, C., Favart, D., Forthomme, L., Giammanco, A., Grégoire, G., Hollar, J., Lemaitre, V., Liao, J., Militaru, O., Nuttens, C., et al. (2011). Study of Z boson production in PbPb collisions at nucleon-nucleon centre of mass energy = 2.76 TeV. Physical Review Letters, 106(21), 212301. https://doi.org/10.1103/PhysRevLett.106.212301 (Original work published 2011)