New Exotic Meson and Baryon Resonances from Doubly Heavy Hadronic Molecules
We predict several new exotic doubly heavy hadronic resonances, inferring from the observed exotic bottomoniumlike and charmoniumlike narrow states $X(3872)$, ${Z}_{b}(10610)$, ${Z}_{b}(10650)$, ${Z}_{c}(3900)$, and ${Z}_{c}(4020/4025)$. We interpret the binding mechanism as mostly molecularlike isospin-exchange attraction between two heavy-light mesons in a relative $S$-wave state. We then generalize it to other systems containing two heavy hadrons which can couple through isospin exchange. The new predicted states include resonances in meson-meson, meson-baryon, baryon-baryon, and baryon-antibaryon channels. These include those giving rise to final states involving a heavy quark $Q=c,b$ and antiquark ${\overline{Q}}^{\ensuremath{'}}=\overline{c},\overline{b}$, namely, $D{\overline{D}}^{*}$, ${D}^{*}{\overline{D}}^{*}$, ${D}^{*}{B}^{*}$, $\overline{B}{B}^{*}$, ${\overline{B}}^{*}{B}^{*}$, ${\mathrm{\ensuremath{\Sigma}}}_{c}{\overline{D}}^{*}$, ${\mathrm{\ensuremath{\Sigma}}}_{c}{B}^{*}$, ${\mathrm{\ensuremath{\Sigma}}}_{b}{\overline{D}}^{*}$, ${\mathrm{\ensuremath{\Sigma}}}_{b}{B}^{*}$, ${\mathrm{\ensuremath{\Sigma}}}_{c}{\overline{\mathrm{\ensuremath{\Sigma}}}}_{c}$, ${\mathrm{\ensuremath{\Sigma}}}_{c}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}$, ${\mathrm{\ensuremath{\Sigma}}}_{c}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{b}$, ${\mathrm{\ensuremath{\Sigma}}}_{b}{\overline{\mathrm{\ensuremath{\Sigma}}}}_{b}$, ${\mathrm{\ensuremath{\Sigma}}}_{b}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{b}$, and ${\mathrm{\ensuremath{\Sigma}}}_{b}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}$, as well as corresponding $S$-wave states giving rise to $Q{Q}^{\ensuremath{'}}$ or $\overline{Q}{\overline{Q}}^{\ensuremath{'}}$.