Muon polarization inKL0→μμ―decay as a test ofCP-violation models

We have calculated the muon polarization in $K_L^0\to {\mu }^{+}{\mu }^{-}$ decay in the left-right-symmetric model of $\mathrm{CP}$ violation with Majorana neutrinos and show that it can be as large as (2 × ${10}^{-2\mathrm{}}$)-(2 × ${10}^{-3\mathrm{}}$) for $m_{W_R}\simeq 1$ TeV, which is larger than the contribution of the $K_1^0$ admixture in $K_L^0$ present in all models of $\mathrm{CP}$ violation. The contribution of the Kobayashi-Maskawa model as well as that of the left-right models with Dirac neutrions to this effect is easily masked by the "background" contribution. Thus, measurement of muon polarization in $K_L^0\to \mu \bar{\mu }$ decay at the 1% level can be used to test both left-right symmetry and the Majorana character of the neutrino.