GENERALIZED NAMBU-JONA-LASINIO MODEL IN A STUDY OF THE BOSON-EXCHANGEMODEL OF NUCLEAR-FORCES

In this paper we discuss the role of chiral symmetry in the descriptio n of the nucleon-nucleon interaction. We make use of a generalized Nam bu-Jona-Lasinio model which exhibits chiral symmetry at the quark leve l and demonstrate how the various components of the boson-exchange mod el of the nucleon-nucleon interaction arise in this model. In this pap er we make use of our recent analysis of correlated two-pion exchange. We have found that when correlated two-pion exchange is represented b y an effective low-mass sigma meson, that meson may be seen to be the chiral partner of the pion. (That result pertains if the meson momentu m q is spacelike such that t=q(2)<0.) We give particular attention to the vertex functions appearing in the boson-exchange model. For monopo le forms of the vertex functions the cutoff parameter Lambda(OBE) vari es from about 1.3 GeV to 2.0 GeV. In our model the nucleon form factor s characterized by a parameter lambda. We show how large cutoff parame ters, such as Lambda(OBE), can arise in our analysis even if the meson -nucleon vertex is soft, with a characteristic cutoff of about 800 MeV . We present the values of lambda that puts the NJL analysis in good a greement with the boson-exchange model of the nucleon-nucleon force.