Measurement of the branching fraction for the decay $K_S \to \pi \mu \nu$ with the KLOE detector

D. Babusci; M. Berlowski; C. Bloise; F. Bossi; P. Branchini; A. Budano; B. Cao; F. Ceradini; P. Ciambrone; F. Curciarello; E. Czerwisnski; G. D'Agostini; E. Danè; V. De Leo; E. De Lucia; A. De Santis; P. De Simone; A. Di Cicco; A. Di Domenico; D. Domenici; A. D'Uffizi; A. Fantini; P. Fermani; S. Fiore; A. Gajos; P. Gauzzi; S. Giovannella; E. Graziani; V. L. Ivanov; T. Johansson; X. Kang; D. Kisielewska-Kamisnska; E. A. Kozyrev; W. Krzemien; A. Kupsc; P. A. Lukin; G. Mandaglio; M. Martini; R. Messi; S. Miscetti; D. Moricciani; P. Moskal; S. Parzych; A. Passeri; V. Patera; E. Perez del Rio; P. Santangelo; M. Schioppa; A. Selce; M. Silarski; F. Sirghi; E. P. Solodov; L. Tortora; G. Venanzoni; W. Wislicki; M. Wolke

doi:10.1016/j.physletb.2020.135378

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arXiv · 1912.05990

Measurement of the branching fraction for the decay $K_S \to \pi \mu \nu$ with the KLOE detector

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Abstract

Based on a sample of 300 million $K_S$ mesons produced in $\phi \to K_L K_S$ decays recorded by the KLOE experiment at the DA$\Phi$NE $e^+e^-$ collider we have measured the branching fraction for the decay $K_S \to \pi \mu \nu$. The $K_S$ mesons are identified by the interaction of $K_L$ mesons in the detector. The $K_S \to \pi \mu \nu$ decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of $K_L \to \pi \mu \nu$ decays. A fit to the reconstructed muon mass distribution finds $7223 \pm 180$ signal events. Normalising to the $K_S \to \pi^+ \pi^-$ decay events the result for the branching fraction is $\mathcal{B}(K_S \to \pi \mu \nu) = (4.56 \pm 0.11_{\rm stat} \pm 0.17_{\rm syst})\times10^{-4}$.

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D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwisnski, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamisnska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wislicki, M. Wolke. 2019-12-12. Measurement of the branching fraction for the decay $K_S \to \pi \mu \nu$ with the KLOE detector. https://doi.org/10.1016/j.physletb.2020.135378

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