Predicted Exotic Doubly Heavy-Strange Pentaquarks

We predict exotic doubly heavy--strange pentaquarks with minimal quark content $u\bar d sQQ'$ ($QQ'=cc,bc,bb$) within a coupled-channel unitary framework where the interaction is derived from an extension of the local hidden gauge approach to the heavy-quark sector. We obtain a robust spectrum of manifestly exotic states; two states appear in the $u\bar d scc$ sector, three in $u\bar d scb$, and four in $u\bar d sbb$. These emerge either as bound states or resonances, along with five additional virtual states manifested as threshold cusps. The binding mechanism is dominated by off-diagonal transitions among heavy-baryon--light-meson channels, while diagonal interactions are strongly suppressed. These results extend exotic hadron spectroscopy into the doubly heavy--strange sector and provide concrete targets for future experimental searches.