Abstract
From and events collected with the BESIII experiment, we report the first observation of and spin polarization in decays. The relative phases of the form factors have been measured to be and with and data, respectively. The nonzero value of allows for a direct and simultaneous measurement of the decay asymmetry parameters of and , the latter value being determined for the first time. The average decay asymmetry, , is calculated to be . The asymmetry is extracted for the first time, and is found to be consistent with conservation.
- Received 17 April 2020
- Accepted 18 June 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.052004
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