Change of MIT bag constant in nuclear

The modiied quark-meson coupling model, which features a density dependent bag constant and bag radius in nuclear matter, is checked against the EMC eeect within the framework of dynamical rescaling. Our emphasis is on the change in the average bag radius in nuclei, as evaluated in a local density approximation, and its implication for the rescaling parameter. We nd that when the bag constant in nuclear matter is signiicantly reduced from its free-space value, the resulting rescaling parameter is in good agreement with that required to explain the observed depletion of the structure functions in the medium Bjorken x region. Such a large reduction of the bag constant also implies large and canceling Lorentz scalar and vector potentials for the nucleon in nuclear matter which are comparable to those suggested by the relativistic nuclear phenomenology and nite-density QCD sum rules.