Implications of CP-violating Top-Higgs Couplings at LHC and Higgs Factories

Abstract

We utilise the LHC Run-1 and -2 Higgs data to constrain the CP-violating top-Higgs couplings. In order to satisfy the current full Higgs data sets at $2\sigma$ level, the CP-odd component $C_t^p$ and the CP-even component $C_t^s$ have to be within the ranges $|C_t^p|<0.37$ and $0.85<C_t^s<1.20$, respectively, which is stronger than the LHC Run-1 bound $|C_t^p|<0.54$ and $0.68<C_t^s<1.20$. With the new bound, we explore the impact on the CP-violating top-Higgs couplings in the Higgs production processes $pp\to t\bar{t}h,thj,hh$ at 13 TeV LHC, and $e^{+}{e}^{-}\to hZ,h\gamma$ at future 240 GeV Higgs factories. We find that the cross sections of $pp\to t\bar{t}h$, $pp\to thj$, $pp\to hh$, $e^{+}{e}^{-}\to hZ$ and $e^{+}{e}^{-}\to h\gamma$ can be enhanced up to 1.41, 1.18, 2.20, 1.001 and 1.09 times as large as the SM predictions, respectively. The future precision measurement of the process $e^{+}{e}^{-}\to h\gamma$ with an accuracy of 5\% will be able to constrain $|C_t^p|<0.19$ at most at a 240 GeV $e^{+}{e}^{-}$ Higgs factory.

Comments: references added, version accepted by Phys. Rev. D