Evidence for New $D_s$-Family Molecular States

Abstract

Motivated by the observed $K{D}^{(\ast )}$ molecular candidates $D_{s0}(2317)$ and $D_{s1}(2460)$, their bottom--strange counterparts, $K{\bar{B}}^{(\ast )}$ molecular states, are naturally expected, although not yet experimentally established. This discrepancy may reflect sizable heavy-quark flavor symmetry breaking, which introduces significant model uncertainties. Current studies of heavy-quark flavor symmetry breaking effects still exhibit strong parameter dependence, and further experimental input is required to constrain these effects, in particular regarding possible additional $K^{(\ast )}{D}^{(\ast )}$ and $K^{(\ast )}{\bar{B}}^{(\ast )}$ molecular states. In this work, we examine whether additional $K^{\ast }{D}^{(\ast )}$ molecular states can be identified among the observed $D_s$ resonances. Within the Gaussian expansion method, we solve the Schrödinger equation using $\sigma$, $\rho$, $\omega$, $\pi$, and $\eta$ exchange potentials, systematically including $S$-wave and higher partial waves. We find that $D_{s1}(2700)$ can be interpreted as a pure $P$-wave $D{K}^{\ast }$ molecule, while $D_{s1}(2860)$ and $D_{s3}(2860)$ are well described as $D^{\ast }{K}^{\ast }$ molecular states dominated by the ${}^1{P}_1$ and ${}^5{P}_3$ components, respectively. We also predict additional molecular states with various $J^P$ quantum numbers. These results provide a new description of the charmed-strange spectrum, and once confirmed will provide additional input data for studies of heavy-quark flavor symmetry breaking effects.