Abstract

Studies of $CP$ violation and anomalous couplings of the Higgs boson to vector bosons and fermions are presented. The data were acquired by the CMS experiment at the LHC and correspond to an integrated luminosity of 137 fb$^{-1}$ at a proton-proton collision energy of 13 TeV. The kinematic effects in the Higgs boson's four-lepton decay H $\to$ 4$\ell$ and its production in association with two jets, a vector boson, or top quarks are analyzed, using a full detector simulation and matrix element techniques to identify the production mechanisms and to increase sensitivity to the Higgs boson tensor structure of the Higgs boson interactions. A simultaneous measurement is performed of up to five Higgs boson couplings to electroweak vector bosons (HVV), two couplings to gluons (Hgg), and two couplings to top quarks (Htt). The $CP$ measurement in the Htt interaction is combined with the recent measurement in the H $\to$ $\gamma\gamma$ channel. The results are presented in the framework of anomalous couplings and are also interpreted in the framework of effective field theory, including the first study of $CP$ properties of the Htt and effective Hgg couplings from a simultaneous analysis of the gluon fusion and top-associated processes. The results are consistent with the standard model of particle physics.

Highlights

  • The discovery by the ATLAS and CMS Collaborations of a Higgs boson (H) with a mass of ≈125 GeV [1,2,3] has confirmed the predictions of the standard model (SM) of particle physics [4,5,6,7,8,9,10]

  • We describe the measurement of fgag3H in the ggH process, fHCPtt in the ttH and tH processes, and the combination of the two where the top quark contributes to the gluon fusion loop

  • The improvements result from a significantly increased sample of H bosons and from a detailed analysis of kinematic distributions of the particles associated with the H boson production in addition to kinematic distributions in its decay

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Summary

Introduction

The discovery by the ATLAS and CMS Collaborations of a Higgs boson (H) with a mass of ≈125 GeV [1,2,3] has confirmed the predictions of the standard model (SM) of particle physics [4,5,6,7,8,9,10]. In theories beyond the SM (BSM), H boson interactions may generate several of them, which lead to new interaction tensor structures, both CP even and CP odd. The new anomalous tensor structures of the H boson interactions may appear through loop corrections in SM processes, but the size of their contributions is beyond the current experimental sensitivity. The CP-odd anomalous couplings between the H boson and either the top quark or new BSM particles, fermions or bosons, contributing to the gluon fusion loop may generate CP violation in Hgg interactions (where g stands for gluon).

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