Abstract
We study the direct production of the charmonium state in electron-positron annihilation by carrying out an energy scan around the mass of the . The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process and the background processes and is observed by combining all the data samples. The signal is observed with a significance of . This is the first observation of a -even state directly produced in annihilation. The electronic width of the resonance is determined to be , which is of the same order of magnitude as theoretical calculations.
- Received 23 March 2022
- Revised 22 June 2022
- Accepted 26 July 2022
DOI:https://doi.org/10.1103/PhysRevLett.129.122001
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