Observation of D0 → K1 (1270) -e+νe

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; 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.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, D. Y.; Chen, G.; Chen, H. S.; Chen, M. L.; Chen, S. J.; Chen, X. R.

来源：Physical Review Letters, 2021, 127(13): 131801.

DOI：10.1103/PhysRevLett.127.131801

• SEMILEPTONIC-B
• TAU-DECAYS
• MESONS
• MODEL

Using 2.93 fb(-1) of e(+)e(-) collision data taken with the BESIII detector at a center-of-mass energy of 3.773 GeV, the observation of the D-0 -> K-1 (1270)(-)e(+)nu(e) semileptonic decay is presented. The statistical significance of the decay D-0 -> K-1 (1270)e(+)nu(e) is greater than 10 sigma. The branching fraction of D-0 -> K-1 (1270)(-)e(+)nu(e) is measured to be (1.09 +/- 0.13(-0.16)(+0.09) +/- 0.12) x 10(-3). Here, the first uncertainty is statistical, the second is systematic, and the third originates from the assumed branching fraction of K-1 (1270)(-) -> K-pi(+)pi(-). The fraction of longitudinal polarization in D-0 -> K-1 (1270)(-)e(+)nu(e) is determined for the first time to be 0.50 +/- 0.19(stat )+/- 0.08(syst).