Measurement of the branching fraction for the decay KS --> pi e nu
arXiv:hep-ph/0203232 · doi:10.1016/S0370-2693(02)01733-1
Abstract
We present a measurement of the branching ratio BR(KS --> pi e nu) performed using the KLOE detector. KS mesons are produced in the reaction e+ e- --> phi --> KS KL at the DAFNE collider. In a sample of about 5 million KS-tagged events we find 624 +- 30 semileptonic KS decays. Normalizing to the KS --> pi+ pi- count in the same data sample, we obtain BR(KS --> pi e nu) = (6.91 +- 0.37) 10^-4, in agreement with the Standard Model expectation.
9 pages, 5 Encapsulated Postscript figures. Submitted to Phys. Lett. B