Search for the Exclusive W Boson Hadronic Decays <i>W</i><SUP>±</SUP> → π<SUP>±</SUP>γ, <i>W</i><SUP>±</SUP> → <i>K</i><SUP>±</SUP>γ and <i>W</i><SUP>±</SUP> → ρ<SUP>±</SUP>γ with the ATLAS Detector

Abstract

A search for the exclusive hadronic decays W-+/- -> pi(+/-)gamma, W-+/- -> K-+/-gamma and W-+/- -> rho(+/-)gamma is performed using up to 140 fb(-1) of proton-proton collisions recorded with the ATLAS detector at a center-of-mass energy of root s = 13 TeV. If observed, these rare processes would provide a unique test bench for the quantum chromodynamics factorization formalism used to calculate cross sections at colliders. Additionally, at future colliders, these decays could offer a new way to measure the W boson mass through fully reconstructed decay products. The search results in the most stringent upper limits to date on the branching fractions B(W-+/- -> pi(+/-)gamma) < 1.9 x 10(-6), B(W-+/- -> K-+/-gamma) < 1.7 x 10(-6), B(W-+/- -> rho(+/-)gamma) < 5.2 x 10(-6) at 95% confidence level.