Measurement of W and Z Boson Production in 5 TeV pp, p+Pb and Pb+Pb Collisions with the ATLAS Detector


W and Z bosons are short lived and do not interact strongly. Thus their production yields measured via lepton decay channels in lead-lead with respect to proton-proton collisions provide direct tests of both binary collision scaling and possible modification of parton distribution functions (nPDF) due to nuclear effects. Further, the protonlead collisions provide an excellent opportunity to study nPDFs in detail. The ATLAS detector has a broad acceptance in the muon and electron channels, with excellent performance even in the high occupancy environment of central heavy-ion collisions. ATLAS has recorded 0.49 nb−1 of lead-lead data at the new center-of-mass energy of 5.02 TeV. Sizes of weak boson production samples are expected to increase by a factor of eight relative to the available Run 1 data at 2.76 TeV. In addition the data can be compared directly to the 29 nb−1 of proton-lead data collected in Run 1 at the same energy. In this report, W and Z boson production yields, and lepton charge asymmetries from W decays are presented differentially in rapidity and transverse momentum as a function of centrality in lead-lead and proton-lead collisions.

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