Search for CP violation in 𝑾𝑯 production in 13 TeV 𝒑 𝒑 collisions with the ATLAS detector

This note presents a search for CP violation in the production of a Higgs boson in association with a W boson (WH) using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider during Run 2, corresponding to an integrated luminosity of 140fb−1 at a center-of-mass energy of 13 TeV. The analysis focuses on the decay channels of the Higgs boson to pairs of bottom quarks and the W boson to leptons. Fiducial cross-section measurements are performed in the simplified template cross section formalism in bins of an angular variable and the W boson transverse momentum, providing a sensitive probe to CP-violating components in the HWW vertex. The results are interpreted within the framework of the Standard Model Effective Field Theory (SMEFT), and constraints are set on the relevant Wilson coefficient in the Warsaw basis, cH˜W, with an observed (expected) value of [-0.62, 0.85] ([-0.58, 0.59]) at 95% confidence level, computed at a new physics scale Λ=1 TeV.