Meson exchange in nuclei and the EMC effect

Abstract

Assuming the NN interaction in nuclei to proceed via meson exchange only, we calculate the nuclear structure function within the Walecka model which directly follows from the OBE mechanism in relativistic Hartree approximation. The meson part of the structure function is found to be concentrated at extremely small values of the scaling variable ( x≲0.05), being very large in this region since the characteristic momenta of nuclear form factors are of order R −1, R is the nuclear radius. At the same time the nucleon part of the structure function is reduced because of the final-state interaction with the vector meson field of nucleus. As a result the ratio. R( x) = F 2A(N)( x)/ F 2N( x)) is the order of 100 at x<0.05 and about 0.64 at moderate x-values, where F 2A(N)( x) is the nuclear structure function related to one nucleon. This result is not altered when both the exchange corrections to the Walecka model and the many-meson exchange are taken into account. Thus, the exchange by vector meson, which is inherent to the Walecka model, is found to be incompatible with the observed magnitude of the EMC effect.