Canonical description of the new LHCb resonances

Abstract

The LHCb Collaboration has recently observed four $J/\psi \varphi$ structures called $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$ in the $B^{+}\to J/\psi \varphi K^{+}$ decays. We study them herein using a nonrelativistic constituent quark model in which the degrees of freedom are quark-antiquark and meson-meson components. The $X(4140)$ resonance appears as a cusp in the $J/\psi \varphi$ channel due to the near coincidence of the $D_s^{\pm }{D}_s^{\ast \pm }$ and $J/\psi \varphi$ mass thresholds. The remaining three $X(4274)$, $X(4500)$ and $X(4700)$ appear as conventional charmonium states with quantum numbers $3^3{P}_1$, $4^3{P}_0$ and $5^3{P}_0$, respectively; and whose masses and widths are slightly modified due to their coupling with the corresponding closest meson-meson thresholds. A particular feature of our quark model is a lattice-based screened linear confining interaction that has been constrained in the light quark sector and usually produces higher excited heavy-quark states with lower masses than standard quark model predictions.

Comments: 7 pages, 8 tables, 2 figures