Based on a sample of 300 million K-S mesons produced in phi -> KLKSdecays recorded by the KLOE experiment at the DA Phi NE e(+)e(-)collider we have measured the branching fraction for the decay K-S -> pimu nu. The K-S mesons are identified by the interaction of K-L mesons inthe detector. The K-S -> pi mu nu decays are selected by a boosteddecision tree built with kinematic variables and by a time-of-flightmeasurement. Signal efficiencies are evaluated with data control samplesof K-L -> pi mu nu decays. A fit to the reconstructed muon massdistribution finds 7223 +/- 180 signal events. Normalising to the K-S ->pi(+)pi(-) decay events the result for the branching fraction is B(K-S-> pi mu nu) = (4.56 +/- 0.11(stat) +/- 0.17(syst)) x 10(-4). It is thefirst measurement of this decay mode and the result allows anindependent determination of vertical bar V-us vertical bar and a testof the lepton-flavour universality. (c) 2020 The Author. Published byElsevier B.V. This is an open access article under the CC BY license(http://creativecommons.org/licenses/by/4.0/).
Measurement of the branching fraction for the decay KS → πμν with the KLOE detector
Martini M.;
2020-01-01
Abstract
Based on a sample of 300 million K-S mesons produced in phi -> KLKSdecays recorded by the KLOE experiment at the DA Phi NE e(+)e(-)collider we have measured the branching fraction for the decay K-S -> pimu nu. The K-S mesons are identified by the interaction of K-L mesons inthe detector. The K-S -> pi mu nu decays are selected by a boosteddecision tree built with kinematic variables and by a time-of-flightmeasurement. Signal efficiencies are evaluated with data control samplesof K-L -> pi mu nu decays. A fit to the reconstructed muon massdistribution finds 7223 +/- 180 signal events. Normalising to the K-S ->pi(+)pi(-) decay events the result for the branching fraction is B(K-S-> pi mu nu) = (4.56 +/- 0.11(stat) +/- 0.17(syst)) x 10(-4). It is thefirst measurement of this decay mode and the result allows anindependent determination of vertical bar V-us vertical bar and a testof the lepton-flavour universality. (c) 2020 The Author. Published byElsevier B.V. This is an open access article under the CC BY license(http://creativecommons.org/licenses/by/4.0/).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
