Towards Exotic Hidden-Charm Pentaquarks in QCD

Inspired by ${P}_{c}(4380)$ and ${P}_{c}(4450)$ recently observed by LHCb, a QCD sum rule investigation is performed, by which they can be identified as exotic hidden-charm pentaquarks composed of an anticharmed meson and a charmed baryon. Our results suggest that ${P}_{c}(4380)$ and ${P}_{c}(4450)$ have quantum numbers ${J}^{P}=3/{2}^{\ensuremath{-}}$ and $5/{2}^{+}$, respectively. Furthermore, two extra hidden-charm pentaqurks with configurations $\overline{D}{\mathrm{\ensuremath{\Sigma}}}_{c}^{*}$ and ${\overline{D}}^{*}{\mathrm{\ensuremath{\Sigma}}}_{c}^{*}$ are predicted, which have spin-parity quantum numbers ${J}^{P}=3/{2}^{\ensuremath{-}}$ and ${J}^{P}=5/{2}^{+}$, respectively. As an important extension, the mass predictions of hidden-bottom pentaquarks are also given. Searches for these partners of ${P}_{c}(4380)$ and ${P}_{c}(4450)$ are especially accessible at future experiments like LHCb and BelleII.