Abstract
We study the processes and , as well as their charge conjugated processes, at five center-of-mass energies between 4.628 and 4.699 GeV, using data samples corresponding to an integrated luminosity of collected by the BESIII detector at the BEPCII storage ring. Based on a partial reconstruction technique, we find evidence of a structure near the thresholds for and production in the recoil-mass spectrum, which we refer to as the . Fitting with a Breit-Wigner line shape, we find the mass of the structure to be and the width to be , where the first uncertainties are statistical and the second are systematic. The significance of the signal is found to be including both the statistical and systematic uncertainty. We report the Born cross section multiplied by the branching fraction at different energy points. The mass of the is close to that of the . Assuming SU(3) symmetry, the cross section of the neutral channel is consistent with that of the charged one. Hence, we conclude that the is the isospin partner of the .
- Received 26 April 2022
- Revised 17 June 2022
- Accepted 30 June 2022
DOI:https://doi.org/10.1103/PhysRevLett.129.112003
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