CPviolation inK+→π+ll¯ decays

We investigate the possibility of observing CP violation in the process ${\mathit{K}}^{+}$→${\mathrm{\pi }}^{+}$ll¯. We find that, from the point of view of probing the Cabbibo-Kobayashi-Maskawa (CKM) mechanism, the measurement of two-spin correlations of the outgoing leptons is the best recourse. For this purpose, we define a T-violating asymmetry ${\mathit{A}}_{\mathrm{CPV}}$, which is the coefficient of the coefficient of the correlation p ${\mathrm{^}}_{\mathit{l}}$⋅s×s¯ in the differential decay rate. In the standard model we estimate ${\mathit{A}}_{\mathrm{CPV}}$∼1.9×${10}^{\mathrm{-}2}$ for the muon mode, using the currently allowed CKM parameters and a top-quark mass of 200 GeV/${\mathit{c}}^2$.