Weak Response of Nuclear Matter
The quantitative understanding of neutrino interactions with nuclei and nuclear matter is needed to the study of many different problems. In the astrophysics environment, neutrino-nucleon and neutrino-nucleus reaction rates are used as inputs in the simulations of phenomena like supernov$\ae$ explosions and neutron star cooling. In the field of neutrino physics, the quantitative knowledge of neutrino-nucleus cross-section is critical to reduce the systematic uncertainty of the long baseline oscillation experiments. 
It is important to realize that, while neutrinos interacting in stellar matter typically have energies of the order of few MeV, the energies involved in long baseline oscillations experiments are much larger. For example, K2K experiment takes data in the region $E_{\nu} =0.5-3$ GeV. 
In this thesis, we describe how nuclear many-body theory provide a scheme allowing for a consistent treatment of neutrino-nucleus interactions at both high and low energies. We will show our predictions of the neutrino-nucleus cross section in the high energy regime and the results of our calculations for the nuclear matter weak response in the low energy regime.