Test of CP invariance in vector-boson fusion production of the Higgs boson using theOptimal Observablemethod in the ditau decay channel with the ATLAS detector

摘要

A test of CP invariance in Higgs boson production via vector-boson fusion using the method of the Optimal Observable is presented. The analysis exploits the decay mode of the Higgs boson into a pair of ( au ) leptons and is based on 20.3 (mathrm{fb}^{-1}) of proton–proton collision data at (sqrt{s}) = 8?(,mathrm{TeV}) collected by the ATLAS experiment at the LHC. Contributions from CP-violating interactions between the Higgs boson and electroweak gauge bosons are described in an effective field theory framework, in which the strength of CP violation is governed by a single parameter ( ilde{d}). The mean values and distributions of CP-odd observables agree with the expectation in the Standard Model and show no sign of CP violation. The CP-mixing parameter ( ilde{d}) is constrained to the interval ((-0.11,0.05)) at 68% confidence level, consistent with the Standard Model expectation of ( ilde{d}=0).