Terent'ev low-energy theorem in the Extended Nambu-Jona-Lasinio model

The low-energy theorem, derived by Terent'ev within the framework of current algebra, is proved at the quark level within the framework of the Extended Nambu-Jona-Lasinio model.One of the authors (A.N.I.) is pleased to thank Dr. A. Nogová and Dr. J. Boháik for a very kind hospitality during the stay at the Institute of Physics in Bratislava, where this work was finished.