Observation of WW$\gamma$ production and search for H$\gamma$ production in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports the first observation of WWγ production at 13 TeV with a significance of 5.6 sigma, measures its cross section, and searches for associated Higgs production to constrain Higgs-light quark couplings.

Contribution

It provides the first observation of WWγ production at 13 TeV and extends the analysis to search for Higgs-photon production to probe Higgs couplings.

Findings

WWγ production observed with 5.6 sigma significance

Measured fiducial cross section of 5.9 fb for WWγ

Constraints placed on Higgs boson couplings to light quarks

Abstract

The observation of WW$\gamma$ production in proton-proton collisions at a center-of-mass energy of 13 TeV with an integrated luminosity of 138 fb$^{-1}$ is presented. The observed (expected) significance is 5.6 (5.1) standard deviations. Events are selected by requiring exactly two leptons (one electron and one muon) of opposite charge, moderate missing transverse momentum, and a photon. The measured fiducial cross section for WW$\gamma$ is 5.9 $\pm$ 0.8 (stat) $\pm$ 0.8 (syst) $\pm$ 0.7 (modeling) fb, in agreement with the next-to-leading order quantum chromodynamics prediction. The analysis is extended with a search for the associated production of the Higgs boson and a photon, which is generated by a coupling of the Higgs boson to light quarks. The result is used to constrain the Higgs boson couplings to light quarks.