Measurement of electroweak-induced production of W gamma with two jets in pp collisions at sqrt(s) = 8 TeV and constraints on anomalous quartic gauge couplings

TL;DR

This paper measures the electroweak production of W gamma with two jets at 8 TeV, observes a slight excess over the standard model, and sets limits on anomalous gauge couplings, confirming SM predictions within uncertainties.

Contribution

First measurement of electroweak W gamma production with two jets at the LHC, including cross section determination and constraints on anomalous quartic gauge couplings.

Findings

Observed a 2.7 sigma excess over SM without electroweak production.

Measured cross section of 10.8 fb consistent with SM predictions.

Set 95% CL limits on anomalous quartic gauge couplings.

Abstract

A measurement of electroweak-induced production of W gamma and two jets is performed, where the W boson decays leptonically. The data used in the analysis correspond to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS experiment in sqrt(s) = 8 TeV proton-proton collisions produced at the LHC. Candidate events are selected with exactly one muon or electron, missing transverse momentum, one photon, and two jets with large rapidity separation. An excess over the hypothesis of the standard model without electroweak production of W gamma with two jets is observed with a significance of 2.7 standard deviations. The cross section measured in the fiducial region is 10.8 +/- 4.1 (stat) +/- 3.4 (syst) +/- 0.3 (lumi) fb, which is consistent with the standard model electroweak predictions. The total cross section for W gamma production in association with 2 jets in the same fiducial region is measured to be 23.2 +/- 4.3 (stat) +/- 1.7 (syst) +/- 0.6 (lumi) fb, which is consistent with the standard model prediction from the combination of electroweak- and quantum chromodynamics-induced processes. No deviations are observed from the standard model predictions and experimental limits on anomalous quartic gauge couplings f[M, 0-7] / Lambda^4, f[T, 0-2] / Lambda^4, and f[T, 5-7] / Lambda^4 are set at 95% confidence level.