Charmed-strange tetraquarks and their decays in the potential quark model

Abstract

In the framework of a nonrelativistic potential quark model, we investigate the mass spectrum of the $1S$-wave charmed-strange tetraquark states of $cn\overline{s}\overline{n}$ and $cs\overline{n}\overline{n}$ ($n=u$ or $d$) systems. The tetraquark system is solved by a correlated Gaussian method. With the same parameters fixed by the meson spectra, we obtained the mass spectra for the $1S$-wave tetraquark states. Furthermore, based on the predicted tetraquark spectra we estimate their rearrangement decays in a quark-exchange model. We find that the rearrangement decays of the tetraquarks may be mainly driven by the spin-spin interactions. The resonances ${X}_{0}(2900{)}^{0}$ and ${T}_{c\overline{s}0}^{a}(2900{)}^{++/0}$ reported from LHCb may be assigned to be the lowest $1S$-wave tetraquark states ${\overline{T}}_{cs0}^{f}(2818)$ and ${T}_{c\overline{s}0}^{a}(2828)$ classified in the quark model, respectively. It also allows us to extract the couplings for the initial tetraquark states to their nearby $S$-wave interaction channels. We find that some of these couplings turn out to be sizeable. Following the picture of the wave function renormalization for the near-threshold strong $S$-wave interactions, the sizeable coupling strengths can be regarded as an indication of their dynamic origins as candidates for hadronic molecules. Furthermore, our predictions suggest that signals for the $1S$-wave charmed-strange tetraquark states can also be searched in the other channels, such as ${D}^{0}{K}^{+}$, ${D}^{+}{K}^{+}$, ${D}^{*+}{K}^{\ensuremath{-}}$, ${D}^{*+}{K}^{+}$, ${D}^{*0}{K}^{+}$, ${D}^{0}{\overline{K}}^{*0}$, ${D}_{s}^{+}{\ensuremath{\rho}}^{0}$, etc.