We study the hidden-charm pentaquark states udscc with spins 1/2, 3/2, and 5/2 within the QCD sum-rule approach. First, we construct the currents for the particular configuration of pentaquark states that consist of the flavor singlet three-quark cluster uds of spins 1/2 and 3/2 and the twoquark clustercc of spin 1, where both clusters are in a color-octet state. To obtain QCD sum rules, the operator product expansion for the correlators is performed up to dimension-10 condensates. The extracted masses from QCD sum rules for the hidden-charm pentaquark states uds-cc are about 4.6 GeV (5.6 GeV) for spin 1/2 ± , about 5.1 GeV (6.0 GeV) for spin 3/2 ± , about 6.1 GeV (5.9 GeV) for spin 5/2 ± , where the masses of the positive parity states are given in parentheses. Additionally, based on the flavor singlet pentaquark states, it is also shown that other pentaquark states of clusters like udc-cs and usc-cd lead to masses similar to the uds-cc case within error bars. Furthermore, in order to see whether any of the states, observed by the LHCb Collaboration, could be understood as the pentaquark of two clusters in the color-octet state, we study the pentaquark formed by the two clusters udc-cu, where the three-quark cluster is assumed to have the same flavor structure as the above uds cluster. We come to the conclusion that if the observed pentaquark will be found to have spin 1/2 and negative parity, then it could be described as a state of two color-octet clusters. * Electronic address: pimikov@mail.ru since it has been shown in [5] that such clusters of uds andcc yielded the most stable result. To check this assumption, we consider the pentaquark states containing a scalar two-quark cluster and find that such states lead to higher masses than those obtained from pentaquarks with a two-quark cluster of spin 1. Then, we also examine other possible pentaquark states containing the two clusters udc-cs and usc-cd by extending the results of the flavor singlet uds andcc case. Furthermore, the pentaquark states of the two color-octet clusters udc-cu are studied to see if any of the states observed by LHCb could be understood in terms of pentaquark state with color-octet substructure. This paper is organized as follows. Using the above assumptions, we construct in Sec. II the interpolating currents for the hidden-charm pentaquark states with spins 1/2, 3/2, and 5/2 in the form of a product of the currents for these two clusters aswith the color index m. We perform the operator product expansion (OPE) for the correlators with the interpolating currents in Sec. III and present the system of the employed QCD sum rules in Sec. IV. Furthermore, since the relativistic interpolating currents for the fermions can be coupled to the two states with opposite parities when the QCD sum rules are constructed, we discuss how to extract the contribution to a state with definite parity from the system of the QCD sum rules in Sec. IV. Finally, a comprehensive discussion of the results is given in Sec. V.
