Precise measurement of Gamma(K -> e nu(gamma))/Gamma(K -> mu nu(gamma))and study of K -> e nu gamma

Abstract

We present a precise measurement of the ratio R-K = Gamma(K -> enu(gamma))/Gamma(K -> mu nu(gamma)) and a study of the radiativeprocess K -> e nu gamma, performed with the KLOE detector. The resultsare based on data collected at the Frascati e(+)e(-) collider DA Phi NEfor an integrated luminosity of 2.2 fb(-1). We find R-K = (2.493 +/-0.025(stat) +/- 0.019(syst)) x 10(-5), in agreement with the StandardModel expectation. This result is used to improve constraints onparameters of the Minimal Supersymmetric Standard Model with leptonflavor violation. We also measured the differential decay rate dGamma(K -> e nu gamma)/dE(gamma) for photon energies 10 < E-gamma < 250MeV. Results are compared with predictions from theory.