Measurement of the branching fraction of the singly Cabibbo-suppressed decay Λc+ → ΛK+

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Albrecht, M.; Aliberti, R.; Amoroso, A.; An, M. R.; An, Q.; Bai, X. H.; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I; Ban, Y.; Bao, S. S.; Batozskaya, V; Becker, D.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Brueggemann, A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, C.; Chen, Chao; Chen, G.

来源：Physical Review D, 2022, 106(11).

DOI：10.1103/PhysRevD.106.L111101

• WEAK MESONIC DECAYS
• NONLEPTONIC DECAYS

We report a branching fraction measurement of the singly Cabibbo-suppressed decay. thornc..Kthorn 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 GeVand correspond to an integrated luminosity of 6.44 fb-1. The branching fraction of. thornc..Kthorn relative to that of the Cabibbo-favored decay. thornc..pthorn is measured to be R 1/4 Bo. thornc..KthornTHORN Bo. thornc..p thornTHORN 1/4 o4.78 similar to 0.34 similar to 0.20THORN%. Combining with the world-average value of Bo. thornc..pthornTHORN, we obtain Bo. thornc..KthornTHORN 1/4 o6.21 similar to 0.44 similar to 0.26 similar to 0.34THORN x 10-4. Here the first uncertainties are statistical, the second systematic, and the third comes from the uncertainty of the. thornc..p thorn 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.