Zcs states from the Ds*D¯* and J/ψK* coupled channels: Signal in B+→J/ψϕK+ decay

Abstract

We study the ${D}_{s}^{*}{\overline{D}}^{*}$ system in connection with the $J/\ensuremath{\psi}{K}^{*}$ in coupled channels and observe that, within reasonable values of the cutoff used to regularize the loops, the system does not develop a bound state. However, the ${J}^{P}={2}^{+}$ channel has enough attraction to create a strong cusp structure that shows up in the $J/\ensuremath{\psi}{K}^{+}$ invariant mass distribution in the ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\phi}{K}^{+}$ decay at the ${D}_{s}^{*}{\overline{D}}^{*}$ threshold. Such structure is visible in the experimental ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\phi}{K}^{+}$ and ${\overline{B}}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}{K}^{\ensuremath{-}}$ decays, with small statistics, and our results should stimulate further measurements around this region, given the fact that cusp effects provide as valuable information on hadron dynamics as resonances themselves.