S-wave D(*)N molecular states: Σc (2800) and Λc (2940)+?

Theoretically, some works have proposed the hadronic resonances Scd2800_and.cd2940__ to be S- wave DN and DN molecular candidates, respectively. In the framework of QCD sum rules, we investigate whether Scd2800_and.cd2940__ could be explained as the S- wave DN state with JP 1/2 - and the S- wave D N state with JP 3 2 -, respectively. Technically, contributions of operators up to dimension 12 are included in the operator product expansion. The final results are 3.64 +/- 0.33 GeV and 3.73 +/- 0.35 GeV for the S- wave DN state of JP 1 2 - and the S- wave DN state of JP 3 2 -, respectively. They are somewhat bigger than the experimental data of Scd2800_ and.cd2940__, respectively. Since corresponding molecular currents are constructed from local operators of hadrons, the possibility of Scd2800_ and.cd2940__ as molecular states cannot be arbitrarily excluded merely from these disagreements between molecular masses using local currents and experimental data. But then these results imply that Scd2800_ and.cd2940__ could not be compact states. This may suggest a limitation of the QCD sum rule using the local current to determine whether some state is a molecular state or not. As by- products, masses for their bottom partners are predicted to be 6.97 +/- 0.34 GeV for the S- wave B N state of JP 1 2 - and 6.98 +/- 0.34 GeV for the S- wave BN state of J(P) 3/2.