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

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A test of CP invariance in Higgs boson production via vector-boson fusion is performed in the H→ττ decay channel. This test uses the Optimal Observable method and is carried out using 36.1fb −1 of s=13TeV proton–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 parameter d˜ governs the strength of CP violation. No sign of CP violation is observed in the distributions of the Optimal Observable, and d˜ is constrained to the interval [−0.090, 0.035] at the 68% confidence level (CL), compared to an expected interval of d˜∈[−0.035,0.033] based upon the Standard Model prediction. No constraints can be set on d˜ at 95% CL, while an expected 95% CL interval of d˜∈[−0.21,0.15] for the Standard Model hypothesis was expected.

Bibliographic note

44 pages in total, author list starting page 28, 6 figures, 5 tables, published in Phys. Lett. B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2018-14


Original languageEnglish
Article number135426
Number of pages25
JournalPhysical Review Letters
Early online date16 Apr 2020
Publication statusPublished - 10 Jun 2020

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