T-odd correlations in charged Kl4 decays

Abstract

We analyse the sensitivity to physics beyond the SM of T-odd correlations in $K_{\ell 4}$ decays, which do not involve the lepton polarization. We show that a combined analysis of $K^+_{μ4}$ and $K^-_{μ4}$ decays can lead to new constraints about CP violation in $ΔS=1$ charged-current interactions, complementary to those obtained from the transverse muon polarization in $K_{μ3}$ and of comparable accuracy.