Q2Q¯2resonances in the baryon-antibaryon system

Two-quark-two-antiquark mesons which couple strongly to baryon-antibaryon channels are classified. The quantum numbers and masses of prominent states are predicted from the MIT bag model. The couplings of $Q^2{\overline{Q}}^2$ states to $B\overline{B}$ are estimated using the ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ model and peripherality. Though most $Q^2{\overline{Q}}^2$ states do not couple strongly to $B\overline{B}$, many prominent resonances remain. Important $Q^2{\overline{Q}}^2$ resonances in the following processes are enumerated and discussed: elastic $N\overline{N}$ scattering, $N\overline{N}\to {\pi }^{+}{\pi }^{-}$, $N\overline{N}$ resonances at or below threshold, and exotic isotensor baryon-antibaryon resonances.