Exotic dibaryons with a heavy antiquark

We discuss the possible existence of exotic dibaryons with a heavy antiquark, being realized as three-body systems, D^¯(⁎)NN and B^(⁎)NN. These are genuinely exotic states with no quark–antiquark annihilation. We consider the heavy quark spin and chiral symmetries, and introduce the one pion exchange potential between a D^¯(⁎) (B^(⁎)) meson and a nucleon N. As for the NN interaction, we employ the Argonne v₈^′ potential. By solving the coupled-channel equations for PNN and P^⁎NN (P^(⁎)=D^¯(⁎) and B^(⁎)), we find bound states for (I,J^P)=(1/2,0⁻) as well as resonant states for (I,J^P)=(1/2,1⁻) both in D^¯(⁎)NN and B^(⁎)NN systems. We also discuss the heavy quark limit, and find that the spin degeneracy is realized in the bound states with (I,J^P)=(1/2,0⁻) and (1/2,1⁻)