Hidden and doubly heavy molecular states from interactions $D^{(*)}_{(s)}{\bar{D}}^{(*)}_{s}$/$B^{(*)}_{(s)}{\bar{B}}^{(*)}_{s}$ and ${D}^{(*)}_{(s)}D_{s}^{(*)}$/${B}^{(*)}_{(s)}B_{s}^{(*)}$ (2107.00855v3)

Abstract: In this work, we perform a systematical investigation about the possible hidden and doubly heavy molecular states with open and hidden strangeness from interactions of $D^{()}{\bar{D}}^{()}{s}$/$B^{()}{\bar{B}}^{()}{s}$, ${D}^{()}_{s}{\bar{D}}^{()}{s}$/${{B}}^{(*)}{s}{\bar{B}}^{(*)}_{s}$, ${D}^{()}D_{s}^{()}$/${B}^{()}B_{s}^{()}$, and $D_{s}^{()}D_{s}^{()}$/$B_{s}^{()}B_{s}^{()}$ in a quasipotential Bethe-Salpeter equation approach. The interactions of the systems considered are described within the one-boson-exchange model, which includes exchanges of light mesons and $J/\psi/\Upsilon$ meson. Possible molecular states are searched for as poles of scattering amplitudes of the interactions considered. The results suggest that recently observed $Z_{cs}(3985)$ can be assigned as a molecular state of $D^\bar{D}_s+D\bar{D}^_s$, which is a partner of $Z_c(3900)$ state as a $D\bar{D}^*$ molecular state. The calculation also favors the existence of hidden heavy states $D_s\bar{D}s/B_s\bar{B}_s$ with spin parity $J^P=0^+$, $D_s\bar{D}^_s/B_s\bar{B}^_s$ with $1^{+}$, and $D^_s\bar{D}^_s/B^_s\bar{B}^_s$ with $0^+$, $1^+$, and $2^+$. In the doubly heavy sector, the bound states can be found from the interactions $(D^D_s+DD^_s)/(B^B_s+BB^_s)$ with $1^+$, $D_s\bar{D}_s^/B_s\bar{B}_s^$ with $1^+$, $D^D^_s/B^B^_s$ with $1^+$ and $2^+$, and $D^_sD^_s/B^_sB^_s$ with $1^+$ and $2^+$. Some other interactions are also found attractive, but may be not strong enough to produce a bound state. The results in this work are helpful for understanding the $Z{cs}(3985)$, and future experimental search for the new molecular states.