QCD sum rule approach to hadron-hadron interactions

Recent work on the QCD sum rule approach to hadron-hadron interactions is reported. First we explain our motivation and present the formulation of calculating hadron-nucleon scattering lengths by the QCD sum rule, where the relation between the hadron mass in nuclear medium and the hadron-nucleon scattering length is also clarified, Secondly we discuss the results of two applications, the nucleon-nucleon and hyperon-nucleon scattering lengths and the pion-nucleon scattering lengths, In the case of the nucleon-nucleon and hyperon-nucleon scattering lengths we show that the results of the QCD sum rule are in qualitative agreement with the experiment. In the case of the pion-nucleon scattering lengths we show that the results of the QCD sum rule ale consistent with the low-energy theorem.