Study of the branching ratio and charge asymmetry for the decay Ks->pi e nu with the KLOE detector

TL;DR

This paper reports the first measurements of charge asymmetry and form-factor slope in semileptonic Ks decays, providing precise tests of fundamental symmetries and quark mixing parameters using the KLOE detector at DAFNE.

Contribution

It presents the first measurement of charge asymmetry and form-factor slope in semileptonic Ks decays, with improved precision and implications for CPT invariance and quark mixing.

Findings

Measured the ratio G(Ks->pienu)/G(Ks->p+p-(g))=(10.19+-0.13)10-4

Obtained a value for f+(K0)Vus consistent with unitarity

Charge asymmetry AS=(1.5+-9.6stat+-2.9syst)10-3 compatible with CPT invariance

Abstract

Among some 400 million KsKl pairs produced in e+e- annihilations at DAFNE, about 6500 each of Ks->pi+e-nubar and Ks->pi-e+nu decays have been observed with the KLOE detector. From these, the ratio G(Ks->pienu)/G(Ks->p+p-(g))=(10.19+-0.13)10-4 is obtained, improving the accuracy on BR(Ks->pienu) by a factor of four and providing the most precise test of the DeltaS=DeltaQ rule. From the partial width Gamma(Ks->pienu), a value for f+(K0)Vus is obtained that is in agreement with unitarity of the quark-mixing matrix. The lepton charge asymmetry AS=(1.5+-9.6stat+-2.9syst)10-3 is compatible with the requirements of CPT invariance. The form-factor slope agrees with recent results from semileptonic Kl and K+ decays. These are the first measurements of the charge asymmetry and form-factor slope for semileptonic Ks decays.