Study ofCPviolation and light Higgs bosons with muon polarization asymmetry inKL0→μμ¯ decay

We have calculated the CP-violating polarization asymmetry $P_L$ of the outgoing muon in $K_L^0$→μμ¯ decays for the standard model (SM) as well as the minimal charged-Higgs-boson model (MCHM) with natural flavor conservation. Detailed predictions of $P_L$ as a function of the Cabibbo-Kobayashi-Maskawa parameters ρ and δ and the t-quark mass are given. $P_L$ is a sensitive probe for light scalars in both the SM and MCHM. It ranges from 0.02 to 0.86 for scalars lighter than 5 GeV/$c^2$. Charged Higgs bosons can help in enhancing $P_L$.