QCD sum rule study of hidden-charm pentaquarks

摘要

We study the mass spectra of hidden-charm pentaquarks having spin (J = {1over 2}/{3over 2}/{5over 2}) and quark contents (uud c ar{c}). We systematically construct all the relevant local hidden-charm pentaquark currents, and we 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^{+0.17}_{-0.13})?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^{+0.18}_{-0.13})?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^+).