Study on triple-hadron bound states with Gaussian expansion method.

In recent years, more and more exotic hadronic states have been discovered successively. Many of them can be explained as hadronic molecules, such as $D_{s0}^*(2317)$, $X(3872)$, and $P_c$ pentaquark states. Analogous to the formation of nuclei, we study three-body hadronic molecules with the Gaussian expansion method and predict the existence of the $DDK$, $\Xi_{cc}\Xi_{cc}\bar{K}$, and $BB\bar{K}$ bound states, which are likely to be found in the current and updated facilities.