W, Z and photon production in CMS

TL;DR

This paper reports measurements of electroweak boson production in proton-proton and lead-lead collisions at the LHC, comparing experimental results with theoretical predictions to understand the effects of the quark-gluon plasma.

Contribution

It provides the first detailed measurements of W, Z, and photon production in PbPb collisions at 2.76 TeV, including their dependence on collision centrality and comparison with QCD calculations.

Findings

Photon production consistent with expectations from pp collisions.

W and Z production rates scale with the number of binary collisions.

Results agree with next-to-leading-order QCD predictions.

Abstract

The production of electroweak bosons (photons, W and Z particles) in PbPb and pp collisions at sqrt(s) = 2.76 TeV per interacting nucleon pair has been measured with the CMS detector at the LHC. Direct photon production is studied using samples of isolated photons. W and Z bosons are reconstructed through their leptonic decay into muons. Their production rate in PbPb data is studied as a function of the centrality of the collision and compared to that in pp interactions, once normalized by the number of binary nucleon-nucleon interactions. The results are also compared to next-to-leading-order perturbative QCD calculations.