Probing Higgs $CP$ properties at the CEPC

Abstract

In the Circular Electron Positron Collider (CEPC), a measurement of the Higgs CP mixing through $e^{+}{e}^{-}\to ZH\to l^{+}{l}^{-}(e^{+}{e}^{-}/{\mu }^{+}{\mu }^{-})H(\to b\bar{b}/c\bar{c}/gg)$ process is presented, with $5.6\ \mbox{ab}^{-1}$ $e^{+}{e}^{-}$ collision data at the center-of-mass energy of $240\mathrm{GeV}$. In this study, the CP-violating parameter ${\tilde{c}}_{Z\gamma }$ is constrained between the region of $-0.30$ and $0.27$ and ${\tilde{c}}_{ZZ}$ between $-0.06$ and $0.06$ at $68\%$ confidence level. This study demonstrates the great potential of probing Higgs $CP$ properties at the CEPC.