New strange pentaquarks

The new strange pentaquarks observed by LHCb are very likely hadronic molecules consisting of ${\mathrm{\Xi }}_c\bar{D}$ and ${\mathrm{\Xi }}_c{\bar{D}}^{\ast }\mathrm{.}$ We discuss the experimental evidence supporting this conclusion, pointing out the similarities and differences with the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ pentaquarks in the non-strange sector. The latter clearly are hadronic molecules consisting of ${\mathrm{\Sigma }}_c\bar{D}$ and ${\mathrm{\Sigma }}_c{\bar{D}}^{\ast }\mathrm{.}$ Following this line of thought, we predict three additional strange pentaquarks, consisting of ${\mathrm{\Xi }}_c^{\mathrm{\prime }}\bar{D}$ and ${\mathrm{\Xi }}_c^{\mathrm{\prime }}{\bar{D}}^{\ast }\mathrm{.}$ The masses of these states are expected to be shifted upwards by $M({\mathrm{\Xi }}_c^{\mathrm{\prime }})-M({\mathrm{\Xi }}_c)\approx 110$ MeV with respect to the corresponding known strange pentaquarks.