Understanding Possible Proton-Antiproton Enhancement Observed by BES Collaboration

We comment on the quantum numbers and decay channels of the proton-antiproton enhancement observed by BES Collaboration. Based on the general symmetry consideration and available experimental information, we suggest that the quantum number of this possible signal is very likely to be JPC = 0-+, IG = O+, which cannot decay into final states π+π-, 2π0, KK, 3π. Besides its dissociation into pp, the other important mesonic decay modes could be ηππ, η'ππ, ηηη, 4π, KKπ, ηKK, KKππ, 6π. Experimental search of this signal in these meson final states is strongly called for.