Combination of Measurements of C P Properties of Higgs Boson Interactions with Vector Bosons Using Proton-Proton Collisions at

A combination of measurements of the C P properties of Higgs boson interactions with electroweak gauge bosons is presented, using 140     fb − 1 of proton-proton collisions at s = 13     TeV recorded by the ATLAS detector. Results from vector boson fusion H → τ τ / W W * / γ γ , inclusive H → Z Z * , and W H , H → b b ¯ channels are combined. No evidence of C P violation is observed, and constrains on the C P -violating operators in the Standard Model effective field theory framework (SMEFT) are set in the Warsaw basis. The results from the combination improve by over 40% on previous individual limits on c H W ˜ and, for the first time, simultaneous constraints on three coefficients c H W ˜ , c H B ˜ , and c H W ˜ B are set. These limits are the most stringent constraints to date on the relevant Wilson coefficients in the SMEFT framework with minimum model dependence.