Search for invisible decays of the Higgs boson produced at the CEPC

Abstract：

The Circular Electron Positron Collider (CEPC), proposed as a future Higgs boson factory, will operate at a center-of-mass energy of 240 GeV and will accumulate 5.6 ab ⁻¹of integrated luminosity in 7 years. In this study, we estimate the upper limit of BR( $H \rightarrow$ inv) for three independent channels, including two leptonic channels and one hadronic channel, at the CEPC. Based on the full simulation analysis, the upper limit of BR( $H \rightarrow$ inv) could reach 0.26% at the 95% confidence level. In the Stand Model (SM), the Higgs boson can only decay invisibly via $H\rightarrow ZZ^\ast\rightarrow\nu\overline{\nu}\nu\overline{\nu}$ , so any evidence of invisible Higgs decays that exceed BR( $H \rightarrow$ inv) of the SM will indicate a phenomenon that is beyond the SM (BSM). The invariant mass resolution of the visible hadronic decay system $ZH(Z \rightarrow qq$ , $ H \rightarrow$ inv) is simulated, and the physics requirement at the CEPC detector for reaching this is given.