Prediction of doubly-charm hadronic molecules with double strange quarks

In this work, we investigate whether the $T$-doublet charmed-strange mesons and their antiparticles can form hidden-charm hidden-strangeness molecular tetraquarks by applying the one-boson-exchange model. We identify $D_{s1}{\bar{D}}_{s1}$ ($J^{PC}=0^{++},1^{+-},2^{++}$), $D_{s1}{\bar{D}}_{s2}^{\ast }$ ($J^{PC}=1^{+\pm },2^{+\pm },3^{+\pm }$), and $D_{s2}^{\ast }{\bar{D}}_{s2}^{\ast }$ ($J^{PC}=0^{++},1^{+-},2^{++},3^{+-},4^{++}$) as promising hidden-charm hidden-strangeness molecular tetraquark candidates. Notably, the $D_{s1}{\bar{D}}_{s2}^{\ast }$ state with $J^{PC}=2^{+-}$ possesses exotic spin-parity quantum numbers forbidden for conventional mesons, providing a clean experimental signature for exotic hadrons. Moreover, the $D_{s2}^{\ast }{\bar{D}}_{s2}^{\ast }$ state with $J^{PC}=4^{++}$ is a rare high-spin hadronic molecule. We then extend the same framework to discuss the binding properties of the $T_s{T}_s$ systems and construct the mass spectrum of corresponding doubly-charm doubly-strangeness molecular tetraquarks. The promising candidates are $D_{s1}{D}_{s1}$ ($J^P=2^{+}$), $D_{s1}{D}_{s2}^{\ast }$ ($J^P=3^{+}$), and $D_{s2}^{\ast }{D}_{s2}^{\ast }$ ($J^P=4^{+}$), all of which are absolutely flavor-exotic. We encourage experimental searches for these predicted hadronic molecules, which would be a crucial step toward establishing doubly-charm molecular tetraquarks with strangeness $S=0$ or $2$.