A test of C P invariance in Higgs boson production via vector-boson fusion has been performed in the H → γ γ channel using 139     fb − 1 of proton-proton collision data at √ s = 13     TeV collected by the ATLAS detector at the LHC. The optimal observable method is used to probe the C P structure of interactions between the Higgs boson and electroweak gauge bosons, as described by an effective field theory. No sign of C P violation is observed in the data. Constraints are set on the parameters describing the strength of the C P -odd component in the coupling between the Higgs boson and the electroweak gauge bosons in two effective field theory bases: ˜ d in the HISZ basis and c H ˜ W in the Warsaw basis. The results presented are the most stringent constraints on C P violation in the coupling between Higgs and weak bosons. The 95% C.L. constraint on ˜ d is derived for the first time and the 95% C.L. constraint on c H ˜ W has been improved by a factor of 5 compared to the previous measurement.

Aad, G., Abbott, B., Abbott, D.C., Abeling, K., Abidi, S.H., Aboulhorma, A., et al. (2023). Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 131(6), 061802-1-061802-23 [10.1103/PhysRevLett.131.061802].

Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector

Alberghi, G L;Alfonsi, F;Bindi, M;Boscherini, D;Cabras, G;Carratta, G;Cavalli, N;De Castro, S;Fabbri, F;Fabbri, L;Franchini, M;Gabrielli, A;Lasagni Manghi, F;Massa, L;