Line-shape analysis of charmonium resonances

We discuss weather the new enhancements found by BES, alias the $Y(4220)$, $Y(4260)$, $Y(4360)$, and $Y(4390)$ are true resonances. We argue that the nearby thresholds $D_s^*\bar{D}_s^*$, $D\bar{D}_1+\bar{D}D_1$, $D_s\bar{D}_{s1}+\bar{D_s}D_{s1}$ and $D^*\bar{D}_1+\bar{D}^*D_1$, as well as the $\psi(4160)$ and $\psi(4415)$ states have a strong influence over the observed $J/\psi \pi^+\pi^-$ and $h_c \pi^+\pi^-$ line-shapes. We propose an unitarized effective Lagrangian model to study the dynamical effect of the interaction between each known $\psi$ state and its closest thresholds. In addition, we present some of our recent motivating results, using the same model, for the $\psi(3770)$ resonance, where the distortion from a Breit-Wigner line-shape is shown to result not only from the kinematic interference, but also from the influence of the $D^0\bar{D}^0+D^+D^-$ one-loops. Moreover, two poles were found, at about 3.78 GeV and at 3.74 GeV, the second one generated dynamically, yet contributing to the distortion of the line-shape.Comment: Proceedings of the Conference "Hadron 17", held on 25-29 September, 2017, in Salamanca, Spai

The Y(4260)Y(4260) and Y(4360)Y(4360) enhancements within coupled-channels

Puzzling structures have been observed in the charmonium energy region, namely the $Y(4260)$ and the $Y(4360)$, that cannot be easily accommodated within quark model frameworks. The proximity of nearby dominant hadronic thresholds suggests that they play an important role in the formation of the enhancements. We present results of an unitarized effective Lagrangian model, where mesonic loops, equivalent to coupled-channels, and charmonium vectors $\psi$ interplay to generate line-shapes and poles.Comment: 4 pages, 2 figures, Conference proceedings at 15th International Workshop on Meson Physics, Krakow, Poland, 7th-12th June 201

Radially excited ψ\psi mesons and the YY enhancements

While many properties of the vector charmonium first excitations are yet to be measured, enhancements at unexpected energies are intriguing, alias the $Y$ states. In order to understand the naturally unquenched mesonic line-shapes, the influence of the most relevant hadronic decay channels must be taken into account. Within an unitary effective approach we present results where mesonic loops are included in an equivalent manner to coupled-channels. We show results for the $\psi(3770)$ and $\psi(4160)$ systems, where we find the nonperturbative effects of dynamical generation of poles and line-shape distortion.Comment: 7 pages, 4 figures, Conference Proceedings of "XIIIth Quark Confinement and Hadron Spectrum", 31 July - 6 August 2018 Maynooth University, Irelan