Ablikim M.Achasov M.N.Baldini Ferroli R.Balossino I.Bertani M.Kolcu, Onur BuğraÇetin, Serkant Ali2022-12-302022-12-302022Ablikim, M., Achasov, M. N., Adlarson, P., Albrecht, M., Aliberti, R., Amoroso, A., ... & Jiang, S. S. (2022). Measurement of the branching fraction of the singly Cabibbo-suppressed decay Λ c+→ Λ K+. Physical Review D, 106(11), L111101.2470-0010http://dx.doi.org/10.1103/PhysRevD.106.L111101https://hdl.handle.net/20.500.12713/3792We report a branching fraction measurement of the singly Cabibbo-suppressed decay ?c+??K+ using a data sample collected with the BESIII detector at the BEPCII storage ring. The data span center-of-mass energies from 4.599 to 4.950 GeV and correspond to an integrated luminosity of 6.44 fb-1. The branching fraction of ?c+??K+ relative to that of the Cabibbo-favored decay ?c+???+ is measured to be R=B(?c+??K+)B(?c+???+)=(4.78±0.34±0.20)%. Combining with the world-average value of B(?c+???+), we obtain B(?c+??K+)=(6.21±0.44±0.26±0.34)×10-4. Here the first uncertainties are statistical, the second systematic, and the third comes from the uncertainty of the ?c+???+ branching fraction. This result, which is more precise than previous measurements, does not agree with theoretical predictions, and suggests that nonfactorizable contributions have been underestimated in current models. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.eninfo:eu-repo/semantics/openAccessArticleWOS:0009282367000012-s2.0-85143789224Q110.1103/PhysRevD.106.L111101Q1