A quantitative understanding of the weak nuclear response is a prerequisite for the analyses of neutrino experiments such as K2K and MiniBOONE, which measure energy and angle of the muons produced in neutrino-nucleus interactions in the energy range 0:5-3 GeV and reconstruct the incident neutrino energy to determine neutrino oscillations. In this paper we discuss theoretical calculations of electron-and neutrino-nucleus scattering, carried out within the impulse approximation scheme using realistic nuclear spectral functions. Comparison between electron scattering data and the calculated inclusive cross section of oxygen, at beam energies ranging between 700 and 1200 MeV, show that the Fermi gas model, widely used in the analysis of neutrino oscillation experiments, fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed.

We discuss the observed disagreement between the Q 2 distributions of neutrino-nucleus quasielastic events, measured by a number of recent experiments, and the predictions of Monte Carlo simulations based on the relativistic Fermi gas model. The results of our analysis suggest that these discrepancies are likely to be ascribable to both the breakdown of the impulse approximation and the limitations of the Fermi gas description. Several issues related to the extraction of the Q 2 distributions from the experimental data are also discussed, and new kinematical variables, which would allow for an improved analysis, are proposed.

The consistent description of the nuclear response at low and high momentum transfer requires a unified dynamical model, suitable to account for both short- and long-range correlation effects. We report the results of a study of the charged current weak response of symmetric nuclear matter, carried out using an effective interaction obtained from a realistic model of the nucleon-nucleon force within the formalism of correlated basis functions. Our approach allows for a clear identification of the kinematical regions in which different interaction effects dominate

Correlated basis function perturbation theory and the formalism of cluster expansions have been recently employed to obtain an effective interaction from a state-of-the-art nucleon nucleon potential model. The approach based on the effective interaction allows for a consistent description of the nuclear matter ground state and nucleon-nucleon scattering in the nuclear medium. This paper reports the the results of numerical calculations of different properties of nuclear and neutron matter, including the equation of state and the shear viscosity and thermal conductivity transport coefficients, carried out using the effective interaction.

We discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out using realistic nuclear spectral functions and including the effect of final state interactions. Comparison between electron scattering data and the calculated inclusive cross sections off oxygen shows that the Fermi gas model fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed. The role of Pauli blocking in charged-current neutrino induced reactions at low $Q^2$ is also analyzed.Comment: To be published in the Proceedings of NUFACT05 (Nucl. Phys. B, Proceedings Supplements

In the impulse approximation regime the nuclear response to a weakly interacting probe can be written in terms of the measured nucleon structure fuctions and the target spectral function, yielding the energy and momentum distribution of the constituent nucleons. We discuss a calculation of charged current neutrino-oxygen interactions in the quasielastic channel, carried out within nuclear many body theory. The proposed approach, extensively and successfully employed in the analysys of electron-nucleus scattering data, allows for a parameter free prediction of the neutrino-nucleus cross section, whose quantitative understanding will be critical to the analysis of the next genaration of high precision neutrino oscillation experiments.

Abstract. A quantitative understanding of the weak nuclear response is a prerequisite for the computer simulations of astrophysical phenomena like supernovae explosions and neutron star cooling. In order to reduce the systematic uncertainties associated with the simulations, a consistent framework, able to take into account dynamical correlation effects, is needed to compute neutrino-nucleon and neutrino-nucleus reaction rates. In this paper we describe the many-body theory of the weak nuclear response at low energy regime. We show how to include both short and long correlations effects in a consistent fashion. IntroductionThe description of neutrino interactions at low momentum transfer (E ν ∼ 10 MeV) with nuclei, and nuclear matter in general, is relevant to the study of many different problems, from supernovae explosions[1] to neutron star cooling [2].The systematic uncertainty associated with computer simulations depends heavily on the values of the neutrino-nucleon and neutrino-nucleus reaction rates used as inputs.Nuclear many body theory provides a scheme allowing for a consistent treatment of neutrinonucleus interactions. Within this approach, nuclear dynamics is described by a phenomenological hamiltonian, whose structure is completely determined by the available data on two-and threenucleon systems, and both short and long range dynamical correlations are taken into account.Over the past decade, the formalism based on correlated wave functions, originally proposed to describe quantum liquids [3], has been employed to carry out highly accurate calculations of the binding energies of both nuclei and nuclear matter, using either the Monte Carlo method [4,5,6] or the cluster expansion formalism and the Fermi Hypernetted Chain integral equations [7,8,9].A different approach, recently proposed in Refs. [10,11] exploits the correlated wave functions to construct an effective interaction suitable for use in standard perturbation theory. This scheme has been employed to obtain a variety of nuclear matter properties, including the neutrino mean free path [10] and the transport coefficients [11,12].In this work we describe the application of the formalism based on correlated wave functions and the effective interaction to the calculation of the weak response of uniform nuclear matter.