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Search for the Exclusive $W$ Boson Hadronic Decays ${W}^{±}\to {\pi }^{±}\gamma $, ${W}^{±}\to {K}^{±}\gamma $ and ${W}^{±}\to {\rho }^{±}\gamma $ with the ATLAS Detector

2024    CERN İşbirliği

A search for the exclusive hadronic decays ${W}^{±}\to {\pi }^{±}\gamma $, ${W}^{±}\to {K}^{±}\gamma $, and ${W}^{±}\to {\rho }^{±}\gamma $ is performed using up to $140\text{}\text{}{\mathrm{fb}}^{-1}$ of proton-proton collisions recorded with the ATLAS detector at a center-of-mass energy of $\sqrt{s}=13\text{}\text{}\mathrm{TeV}$. 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 $B\left({W}^{±}\to {\pi }^{±}\gamma \right)<1.9×{10}^{-6}$, $B\left({W}^{±}\to {K}^{±}\gamma \right)<1.7×{10}^{-6}$, $B\left({W}^{±}\to {\rho }^{±}\gamma \right)<5.2×{10}^{-6}$ at 95% confidence level.