Violation of CP and T in semileptonic decays due to scalar interactions

Abstract

Observing charge-parity (CP) or time-reversal (T) violations in the leptonic sector will give useful information to elucidate the nature of neutrinos. CP-violating couplings in charged leptonic currents carry out the weak phases necessary to break these symmetries. Here we study the interference of $W^{\pm }$ and $H^{\pm }$ bosons mediated amplitudes as the origin of possible CP and T violation in semileptonic decays of $K^{\pm }$ mesons and ${\tau }^{\pm }$ leptons. We use the experimental bound on the T-odd transverse polarization asymmetry in $K_{\mu 3}^{+}$ decays to predict an upper limit on the CP violating effects in $\tau \to K\pi \nu$ decays. In the framework of this model with scalar-mediated interactions, we find that current limits on the former process indicate that the CP violating effects in the latter are much smaller than the limits reported so far.

Comments: 9 pages, 2 figures