High-precision nucleon -nucleon interactions with Brown -Rho scaling medium modifications

Today, the foundation for most theoretical calculations of nuclear properties across the periodic table is one of the several high-precision nonrelativistic nucleon-nucleon potential models based on meson exchange. Although these interactions fit with near perfection all experimental data available for two interacting nucleons, it is well known that such interactions alone are insufficient to describe very accurately the properties of many-nucleon systems close to nuclear matter density. In this thesis we suggest that density-dependent nuclear interactions based on the notion of Brown-Rho scaling can provide one avenue to extend the nuclear interaction to these density regions. We first study symmetric nuclear matter based on both the Goldstone linked diagram expansion and Landau Fermi liquid theory. In the former we sum to all orders the particle-particle hole-hole ring diagrams to obtain the ground state energy as a function of density. We find that the main effect of including Brown-Rho scaling is a reduction in both the saturation density and energy. In the Fermi liquid description of nuclear matter, we show that free-space nucleon-nucleon interactions are unable to describe the quasiparticle effective mass, compression modulus, symmetry energy, and anomalous orbital gyromagnetic ratio at nuclear matter density. By including the effects of Brown-Rho scaling, we show that these observables are in general better reproduced theoretically. Next, we explore the anomalously long lifetime of carbon-14, which has been a persistent puzzle to nuclear structure theorists for decades. We demonstrate that the dropping rho meson mass decreases the nuclear tensor force to such an extent that carbon-14 achieves its archaeologically long lifetime at a density of ∼85% that of saturated nuclear matter. We discuss future applications as well as the connection between medium-modified two-nucleon interactions and many-body forces