Search for high-mass Wγ and Zγ resonances using hadronic W/Z boson decays from 139 fb^–1 of pp collisions at √s̅ = 13 TeV with the ATLAS detector

A search for high-mass charged and neutral bosons decaying to W_γ and Z_γ final states is presented in this paper. The analysis uses a data sample of √s̅ = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb⁻¹ collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the W and Z bosons because of their large branching fractions. The decay products of the high-momentum W/Z bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to W_γ and Z_γ are derived for various boson production models.