Do the $P_c^+$ Pentaquarks Have Strange Siblings?

Abstract

The recent LHCb discovery of states $P_c^+(4380)$, $P_c^+(4450)$, believed to be $c\bar c uud$ pentaquark resonances, begs the question of whether equivalent states with $c\bar c \to s\bar s$ exist, and how they might be produced. The precise analogue to the $P_c^+$ discovery channel $\Lambda_b \to J/\psi \, K^- \! p$, namely, $\Lambda_c \to \phi \pi^0 \! p$, is feasible for this study and indeed is less Cabibbo-suppressed, although its limited phase space suggests that evidence of a $s\bar s uud$ resonance $P_s^+$ would be confined to the kinematic endpoint region.