Analysis of diagonal and nondiagonal QCD sum rules for heavy baryons at next-to-leading order inαS

We consider diagonal and nondiagonal QCD sum rules for the ground state heavy baryons to leading order in ${1/m}_Q$ and at next-to-leading order in ${\alpha }_S.$ In the nondiagonal case we evaluate the eight different two-loop diagrams which determine the perturbative ${\alpha }_S$ corrections to the Wilson coefficient of the quark condensate in the operator product expansion. The QCD corrections to the nondiagonal 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 $m\left({\Lambda }_Q\right)-m_Q\simeq 760$ MeV and $m\left({\Sigma }_Q\right)-m_Q\simeq 940$ MeV. The central values for the residues are given by $F\left({\Lambda }_Q\right)\simeq 0.030$ GeV${}^3$ and $F\left({\Sigma }_Q\right)\simeq 0.038$ GeV${}^3$.