How many vector charmoniumlike states lie in the mass range 4.2–4.35 GeV?

Abstract

In recent years many vector charmonium(like) states were reported by different electron-positron collider experiments above 4.2 GeV. However, so far, there not only exists sizable tension in the parameters of those states, but there is also no consensus on the number of the vector states in this energy range. To some extend, this might be caused by the fact that the experimental data were typically analyzed in single channel analyses employing overlapping Breit-Wigner functions, in particular ignoring the effect of opening thresholds. In this study, we focus on the mass range between 4.2 GeV and 4.35 GeV, conducting a comprehensive analysis of eight different final states in e+e− annihilation. Our findings demonstrate that, within this mass range, a single vector charmoniumlike state, exhibiting properties consistent with a D1D¯ molecular structure and characterized by a pole location spoleY(4230)=(4227±4−i2(50−2+8))  MeV, can effectively describe all the collected data. This is made possible by allowing for an interference with the well-established vector charmonium ψ(4160) along with the inclusion of the D1D¯ threshold effect. Moreover, in contrast to experimental analyses, our study reveals that the highly asymmetric total cross sections for e+e−→J/ψππ and e+e−→J/ψKK¯ around 4230 MeV stem from the same physics, rooted in the approximate SU(3) flavor symmetry of QCD. Published by the American Physical Society 2024