Journal of High Energy Physics (Feb 2023)

Measurement of the KS → πeν branching fraction with the KLOE experiment

  • The KLOE-2 collaboration,
  • D. Babusci,
  • M. Berlowski,
  • C. Bloise,
  • F. Bossi,
  • P. Branchini,
  • B. Cao,
  • F. Ceradini,
  • P. Ciambrone,
  • F. Curciarello,
  • E. Czerwiński,
  • G. D’Agostini,
  • R. D’Amico,
  • E. Danè,
  • V. De Leo,
  • E. De Lucia,
  • A. De Santis,
  • P. De Simone,
  • A. Di Cicco,
  • A. Di Domenico,
  • E. Diociaiuti,
  • D. Domenici,
  • A. D’Uffizi,
  • G. Fantini,
  • A. Gajos,
  • S. Gamrat,
  • P. Gauzzi,
  • S. Giovannella,
  • E. Graziani,
  • X. Kang,
  • A. Kupsc,
  • G. Mandaglio,
  • M. Martini,
  • S. Miscetti,
  • P. Moskal,
  • A. Passeri,
  • E. Perez del Rio,
  • M. Schioppa,
  • A. Selce,
  • M. Silarski,
  • F. Sirghi,
  • E. P. Solodov,
  • W. Wiślicki,
  • M. Wolke

DOI
https://doi.org/10.1007/JHEP02(2023)098
Journal volume & issue
Vol. 2023, no. 2
pp. 1 – 19

Abstract

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Abstract The ratio R $$ \mathcal{R} $$ = Γ(K S → πeν)/Γ(K S → π + π − ) has been measured with a sample of 300 million K S mesons produced in ϕ → K L K S decays recorded by the KLOE experiment at the DAΦNE e + e − collider. K S → πeν events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of K L → πeν decays are used to evaluate signal selection efficiencies. With 49647±316 signal events we measure R $$ \mathcal{R} $$ = (1.0421 ± 0.0066stat ± 0.0075syst) × 10 −3. The combination with our previous measurement gives R $$ \mathcal{R} $$ = (1.0338 ± 0.0054stat ± 0.0064syst) × 10 −3. From this value we derive the branching fraction B $$ \mathcal{B} $$ (K S → πeν) = (7.153 ± 0.037stat ± 0.044syst) × 10 −4 and f +(0)|V us | = 0.2170 ± 0.009.

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