QCD sum rule study of hidden-charm pentaquarks

Abstract

We study the mass spectra of hidden-charm pentaquarks having spin $J=\frac{1}{2}/\frac{3}{2}/\frac{5}{2}$ and quark contents $uudc\bar{c}$. We systematically construct all the relevant local hidden-charm pentaquark currents, and select some of them to perform QCD sum rule analyses. We find that the $P_c(4380)$ and $P_c(4450)$ can be identified as hidden-charm pentaquark states composed of an anti-charmed meson and a charmed baryon. Besides them, we also find a) the lowest-lying hidden-charm pentaquark state of $J^P=1/2^{-}$ has the mass $4.33_{-0.13}^{+0.17}$ GeV, while the one of $J^P=1/2^{+}$ is significantly higher, that is around $4.7-4.9$ GeV; b) the lowest-lying hidden-charm pentaquark state of $J^P=3/2^{-}$ has the mass $4.37_{-0.13}^{+0.18}$ GeV, consistent with the $P_c(4380)$ of $J^P=3/2^{-}$, while the one of $J^P=3/2^{+}$ is also significantly higher, that is above $4.6$ GeV; c) the hidden-charm pentaquark state of $J^P=5/2^{-}$ has a mass around $4.5-4.6$ GeV, slightly larger than the $P_c(4450)$ of $J^P=5/2^{+}$.

Comments: 18 pages, 5 figures and 3 tables. Accepted by Eur. Phys. J. C