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An Analysis of Diagonal and Non-diagonal QCD Sum Rules for Heavy Baryons at Next-to-Leading Order in α_S

We consider diagonal and non-diagonal QCD sum rules for the ground state heavy baryons to leading order in $1/m_Q$ and at next-to-leading order in $α_S$. In the non-diagonal case we evaluate the eight different two-loop diagrams which determine the perturbative $α_S$-corrections to the Wilson coefficient of the quark condensate in the Operator Product Expansion. The QCD corrections to the non-diagonal sum rules are moderate compared to the QCD corrections in the diagonal case. We also consider constituent type sum rules using constituent type interpolating currents. The obtained results are in reasonable agreement with the corresponding results obtained in the diagonal case. As central values for the bound state energies we find $m(Λ_Q)-m_Q = 760 MeV$ and $m(Σ_Q)-m_Q = 940 MeV$. The central values for the residues are given by $F(Λ_Q) = 0.030 GeV^3$ and $F(Σ_Q) = 0.038 GeV^3$.