We perform a complete simulation of the process $e^{+}{e}^{-}\to b\overline{b}\nu \overline{\nu }$, where $\nu$ can be an electron, muon, or tau neutrino, in the context of a general Higgs coupling to $b$ quarks. We parametrize the $Hb\overline{b}$ coupling as $(m_b/v)(a+i{\gamma }_{5}b)$. Taking into account interference effects between pure Higgs and Standard Model contributions, we find that sensitivities of the order of $2\%$ and $20\%$ can be obtained at a future $e^{+}{e}^{-}$ collider for deviations of the $a$ and $b$ parameters, respectively, from their Standard Model values. Combining our analysis with an independent measurement of ${\Gamma }_{H\to b\overline{b}}$ can provide evidence about the $CP$ nature of the Higgs sector.

• Received 30 August 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.241801