Exotic mesons with double charm and bottom flavor

Abstract

We study exotic mesons with double charm and bottom flavor ($|C|=|B|=2$), whose quark configuration is $\overline{\mathrm{Q}}\overline{\mathrm{Q}}\mathrm{qq}$. This quark configuration has no annihilation process of quark and antiquark, and hence is a genuinely exotic state. We take a hadronic picture by considering the molecular states composed of a pair of heavy mesons, such as DD, $\mathrm{D}{\mathrm{D}}^{*}$, and ${\mathrm{D}}^{*}{\mathrm{D}}^{*}$ for charm flavor, and BB, $\mathrm{B}{\mathrm{B}}^{*}$, and ${\mathrm{B}}^{*}{\mathrm{B}}^{*}$ for bottom flavor. The interactions between heavy mesons are derived from the heavy quark effective theory. All molecular states are classified by $I({J}^{P})$ quantum numbers, and are systematically studied up to the total angular momentum $J\ensuremath{\le}2$. By solving the coupled channel Schr\"odinger equations, due to the strong tensor force of one-pion exchange, we find bound and/or resonant states of various quantum numbers.