Study of e+e- ???cJ at center of mass energies from 4.21 to 4.42 GeV

Abstract

Based on data samples collected with the BESIII detector at the BEPCII collider at nine center of mass energies from 4.21 to 4.42 GeV, we search for the production of e+e-???cJ (J=0, 1, 2). The process e+e-???c0 is observed for the first time, and the Born cross sections at s=4.23 and 4.26 GeV are measured to be (55.4±6.0±5.9) and (23.7±5.3±3.5)pb, respectively, where the first uncertainties are statistical and the second are systematic. The ??c0 signals at the other seven energies and the e+e-???c1 and ??c2 signals are not significant, and the upper limits on the cross sections are determined. By examining the ??c0 cross section as a function of center of mass energy, we find that it is inconsistent with the line shape of the Y(4260) observed in e+e-??+?-J/?. Assuming the ??c0 signals come from a single resonance, we extract the mass and width of the resonance to be (4230±8±6)MeV/c2 and (38±12±2)MeV, respectively, and the statistical significance is more than 9?. © 2015 American Physical Society.