Hadron–nucleon scattering lengths are studied by the QCD sum rule. First
we explain our motivation and present the formulation for calculating
hadron-nucleon scattering lengths by the QCD sum rule, where the relation
between the hadron mass in the nuclear medium and the hadron–nucleon
scattering length is also clarified. Secondly we discuss two applications, the
pion–nucleon scattering lengths and the nucleon-nucleon scattering
lengths. In the case of the pion–nucleon scattering length we show that
the results of the QCD sum rule are consistent with the low-energy theorem. In
the case of the nucleon–nucleon scattering lengths we show that the
results of the QCD sum rule are in qualitative agreement with experiment.
Hadron-Nucleon Scattering Lengths from QCD Sum Rules