The new K_S → πe ν branching fraction measurement at KLOE

2024/04/02 by A. Passeri, Passeri, A.
Computer Science · Physics and Astronomy · #Advanced Data Storage Technologies #Distributed and Parallel Computing Systems #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle physics theoretical and experimental studies

paper · pdf · doi:10.48550/arxiv.2404.01826

openalex publication_date 2024/04/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

A new measurement of the branching fraction for the decay K_S → πe ν is presented, based on a sample of 300 million K_S mesons recorded by the KLOE experiment at the DAΦNE e⁺e^- collider. A two-step signal selection strategy is used, exploiting first kinematic variables and then time-of-flight measurements. Data control samples of K_S → πe ν decays are used to evaluate signal selection efficiencies. Normalizing the selected sample to the number of K_S → π⁺ π^- decay events the result for the branching fraction is B(K_S → πe ν)=(7.211 ± 0.046 ± 0.052)× 10^-4. The combination with our previous measurement gives B(K_S → πe ν)=(7.153 ± 0.037 ± 0.043)× 10^-4 =(7.153 ± 0.057)× 10^-4. From this value we derive f⁺(0)|Vus|=0.2170 ± 0.0009.

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