Pentaquarks with hidden charm as hadroquarkonia

We consider hidden charm pentaquarks as hadroquarkonium states in a QCD inspired approach. Pentaquarks arise naturally as bound states of quarkonia excitations and ordinary baryons. The LHCb P-c(4450) pentaquark is interpreted as a psi'-nucleon bound state with spin-parity J(P) = 3/2(-). The partial decay width Gamma (P-c(4450) -> J/psi + N) approximate to 11 MeV is calculated and turned out to be in agreement with the experimental data for P-c(4450). The P-c(4450) pentaquark is predicted to be a member of one of the two almost degenerate hidden-charm baryon octets with spin-parities J(P) = 1/2(-), 3/2(-). The masses and decay widths of the octet pentaquarks are calculated. The widths are small and comparable with the width of the P-c(4450) pentaquark, and the masses of the octet pentaquarks satisfy the Gell-Mann-Okubo relation. Interpretation of pentaquarks as loosely bound Sigma(c)(D) over bar* and Sigma(c)*(D) over bar* deuteronlike states is also considered. We determine quantum numbers of these bound states and calculate their masses in the one-pion exchange scenario. The hadroquarkonium and molecular approaches to exotic hadrons are compared and the relative advantages and drawbacks of each approach are discussed.