/ nucl-ex CMS-HIN-13-004

Study of Z production in PbPb and pp collisions at $\sqrt{s_{NN}}$ = 2.76 TeV in the dimuon and dielectron decay channels

Pages: 37

Abstract: The production of Z bosons is studied in the dimuon and dielectron decay channels in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV, using data collected by the CMS experiment at the LHC. The PbPb data sample corresponds to an integrated luminosity of about $150~\mu\mathrm{b}^{-1}$, while the pp data sample collected in 2013 at the same nucleon-nucleon centre-of-mass energy has an integrated luminosity of $5.4~\mathrm{pb}^{-1}$. The Z boson yield is measured as a function of rapidity, transverse momentum, and collision centrality. The ratio of PbPb to pp yields, scaled by the number of inelastic nucleon-nucleon collisions, is found to be $1.06\pm0.05~\mathrm{(stat)}\pm0.08~\mathrm{(syst)}$ in the dimuon channel and $1.02\pm0.08~\mathrm{(stat)}\pm0.15~\mathrm{(syst)}$ in the dielectron channel, for centrality-integrated Z boson production. This binary collision scaling is seen to hold in the entire kinematic region studied, as expected for a colourless probe that is unaffected by the hot and dense QCD medium produced in heavy ion collisions.

Note: Submitted to JHEP

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