Abstract
Using of collision data taken with the BESIII detector at a center-of-mass energy of 3.773 GeV, the observation of the semileptonic decay is presented. The statistical significance of the decay is greater than . The branching fraction of is measured to be . Here, the first uncertainty is statistical, the second is systematic, and the third originates from the assumed branching fraction of . The fraction of longitudinal polarization in is determined for the first time to be .
- Received 22 February 2021
- Revised 28 July 2021
- Accepted 18 August 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.131801
Published by the American Physical Society under the terms of the 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.
Published by the American Physical Society