Hidden-charm pentaquark formation in antiproton-deuterium collisions

The possibility of observing formation of hidden-charm pentaquarks as s-channel resonances in antiproton-deuteron collisions is discussed. It is pointed out that the masses of the reported by LHCb pentaquark resonances in the J/ψp channel are very close to a special value of the mass at which formation of a pentaquark by antiproton incident on a deuteron at rest requires exactly the same momentum of the p as needed for the formation in the s channel of the charmonium resonance in pp collisions with the proton being at rest. For this reason the former process can be rather completely described within the notion of the deuteron being a shallow bound state of two nucleons without resorting to models describing its short-distance structure. It is argued that a similar kinematical coincidence can be expected for (yet) hypothetical pentaquark resonances in the ηcN channel, and that these can be sought for once antiproton-deuterium collisions become available for experimentation.