QCD sum rules and the determination of leading twist non-singlet operator matrix elements

We use QCD sum rules to determine directly the leading twist non-singlet operator matrix elements based on calculations of three-point correlation functions in configuration space. We find a different result from that obtained by integrating the structure functionsʹ expressions obtained by Belyaev and Ioffe based on calculations of four-point correlators in momentum space. The origin of this discrepancy remains unclear.