Measurement of the Z gamma production cross section in pp collisions at 8 TeV and search for anomalous triple gauge boson couplings

TL;DR

This paper measures the Z gamma production cross section in proton-proton collisions at 8 TeV using CMS data, and searches for anomalous triple gauge couplings, providing results consistent with QCD predictions and setting new limits on gauge couplings.

Contribution

It presents the first measurement of Z gamma production cross section at 8 TeV and sets improved limits on anomalous triple gauge couplings.

Findings

Measured cross sections agree with NNLO QCD predictions.

Set new limits on anomalous Z Z gamma and Z gamma gamma couplings.

Provided differential cross sections as a function of photon transverse momentum.

Abstract

The cross section for the production of Z gamma in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 inverse femtobarns. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of Z Z gamma and Z gamma gamma are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.