Abstract
We study at center-of-mass energies from 3.90 to 4.42 GeV by using data samples collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections are measured at 13 energies and are found to be of the same order of magnitude as those of but with a different line shape. In the mass spectrum, a distinct structure, referred to as , is observed at . The carries an electric charge and couples to charmonium. A fit to the invariant mass spectrum, neglecting possible interferences, results in a mass of and a width of for the , where the first errors are statistical and the second systematic. The difference between the parameters of this structure and the observed in the final state is within , but whether they are the same state needs further investigation. No significant signal is observed, and upper limits on the production cross sections in at center-of-mass energies of 4.23 and 4.26 GeV are set.
- Received 7 September 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.242001
© 2013 American Physical Society