Test of CP invariance in vector-boson fusion production of the Higgs boson in the H?→? ττ channel in proton–proton collisions at s = 13 TeV with the ATLAS detector

摘要

A test of CP invariance in Higgs boson production via vector-boson fusion is performed in theH→ττdecay channel. This test uses the Optimal Observable method and is carried out using36.1fb?1ofs=13TeVproton–proton collision data collected by the ATLAS experiment at the LHC. Contributions from CP-violating interactions between the Higgs boson and electroweak gauge bosons are described by an effective field theory, in which the parameterd?governs the strength of CP violation. No sign of CP violation is observed in the distributions of the Optimal Observable, andd?is constrained to the interval [?0.090, 0.035] at the 68% confidence level (CL), compared to an expected interval ofd?∈[?0.035,0.033]based upon the Standard Model prediction. No constraints can be set ond?at 95% CL, while an expected 95% CL interval ofd?∈[?0.21,0.15]for the Standard Model hypothesis was expected.