Contact interaction in the nonrelativistic pion absorption operator
  Chirally invariant Lagrangian containing nucleon, pion and chiral scalar fields is considered. A consistent scheme is proposed for obtaining the nonrelativistic operator of pion absorption by NN-pair taking into account the chiral scalar exchange. An important role of the contact interaction is pointed out.D 
D.A.Zaikin and I.I.Osipchuk