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Compact Muon Solenoid
LHC, CERN

CMS-PAS-HIG-20-006
Analysis of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons in proton-proton collisions at s= 13 TeV
Abstract: The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons is presented. The measurement is based on data collected in proton-proton collisions at s= 13 TeV by the CMS experiment at the CERN LHC in 2016, 2017 and 2018, corresponding to an integrated luminosity of 137 fb1. Events are selected where one τ decays to a muon and the other hadronically, and where both τ leptons decay hadronically. These are the most sensitive decay modes for this analysis and together cover about 50% of all Higgs-to-tau decays. The analysis uses the angular correlation between the decay planes of τ leptons produced in Higgs boson decays. Machine learning techniques are deployed to distinguish between signal and background events, and dedicated analysis techniques are used to optimise the reconstruction of the τ decay planes. The mixing angle between CP-even and CP-odd τ Yukawa couplings was found to be 4 ± 17, compared to an expected uncertainty of ± 23 at the 68% confidence level, while at the 95% confidence level the observed (expected) uncertainties were ± 36 (± 55). The observed (expected) significance of the separation between the CP-even and CP-odd hypotheses is 3.2 (2.3) standard deviations. The results are compatible with predictions for the standard model Higgs boson.
CMS Publications
Compact Muon Solenoid
LHC, CERN