Physics Letters B (Jul 2018)

First measurement of the K−n →Λπ− non-resonant transition amplitude below threshold

  • K. Piscicchia,
  • S. Wycech,
  • L. Fabbietti,
  • M. Cargnelli,
  • C. Curceanu,
  • R. Del Grande,
  • J. Marton,
  • P. Moskal,
  • A. Scordo,
  • M. Silarski,
  • D. Sirghi,
  • M. Skurzok,
  • I. Tucakovic,
  • O. Vázquez Doce,
  • J. Zmeskal,
  • P. Branchini,
  • E. Czerwinski,
  • V. De Leo,
  • E. De Lucia,
  • A. Di Cicco,
  • P. Fermani,
  • S. Fiore,
  • W. Krzemien,
  • G. Mandaglio,
  • M. Martini,
  • E. Perez del Rio,
  • A. Selce

Journal volume & issue
Vol. 782
pp. 339 – 345

Abstract

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We present the analysis of K− absorption processes on He4 leading to Λπ− final states, measured with the KLOE spectrometer at the DAΦNE e+e− collider and extract, for the first time, the modulus of the non-resonant K−n →Λπ− direct production amplitude about 33 MeV below the K‾N threshold. This analysis also allows to disentangle the K− nuclear absorption at-rest from the in-flight capture, for K− momenta of about 120 MeV. The data are interpreted with the help of a phenomenological model, and the modulus of the non-resonant K−n →Λπ− amplitude for K− absorption at-rest is found to be |AK−n→Λπ−|=(0.334±0.018stat−0.058+0.034syst)fm. Keywords: Strong interaction, Strangeness nuclear physics, Antikaon interactions in nuclear matter