Saturation in the Nuclear Matter Problem

Once density-dependent meson masses are introduced into the nuclear many-body problem, conventional mechanisms for saturation no longer operate. We suggest that a loop correction, essentially the introduction of the axial vector coupling $g_A(\rho,k)$ as function of density $\rho$ and momentum $k$, can bring about saturation, and present schematic calculations to illustrate this. We find that a very small density-dependence in $g_A$ gives rise to a very large saturating effect on nuclear matter. In fact, this new saturation mechanism turns out to be more powerful than any of the conventional mechanisms.