On the behaviour of the nuclear spectral function at high momentum and removal energy

The extrapolation of the nuclear spectral function at large nucleon three-momentum and removal energy is suggested.Comment: 13 pages, 2 Postscript figure

Backward hadron production in neutrino-nucleus interactions

The production of backward pions in lepton-nucleus collisions is analyzed. We show that a large yield of high momentum backward pions can be explained by the Regge asymptotic of the distribution of nucleons carrying a large momentum fraction in the nuclear target. The calculated spectra of pions emitted in the neutrino + Ne --> muon + pion + X reaction are in satisfactory agreement with the available experimental data.Comment: 11 pages, 3 figure

Q**2-dependence of semi-inclusive electron-nucleus scattering and nucleon-nucleon correlations

We analize semi-inclusive electron-nucleus processes e+A->e'+h+X at moderate Q**2 and energy transfer nu. Our results show that nucleons bound in the nuclear medium are distributed according to a function f_A that reduces to the standard light-cone distribution in the Bjorken limit and exhibits a sizeable Q**2-dependence at lower Q**2, particular Q**2 is order of nu**2.Comment: 8 pages of LaTeX-text and 2 figure ps-file

Deuteron distribution in nuclear matter

We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana $v_{14}$ two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions theory. We study the differences between the S- and D-wave components of the deuteron and those of the deuteron-like pair in the nuclear medium. The total number of deuteron type pairs is computed and compared with the predictions of Levinger's quasideuteron model. The resulting Levinger's factor in nuclear matter at equilibrium densityis 11.63. We use the local density approximation to estimate the Levinger's factor for heavy nuclei, obtaining results which are consistent with the available experimental data from photoreactions.Comment: 22 pages, 7 figures, typeset using REVTe

Short-range Correlations in a CBF description of closed-shell nuclei

The Correlated Basis Function theory (CBF) provides a theoretical framework to treat on the same ground mean-field and short-range correlations. We present, in this report, some recent results obtained using the CBF to describe the ground state properties of finite nuclear systems. Furthermore we show some results for the excited state obtained with a simplified model based on the CBF theory.Comment: 10 latex pages plus 6 uuencoded figure

Quenching of Weak Interactions in Nucleon Matter

We have calculated the one-body Fermi and Gamow-Teller charge-current, and vector and axial-vector neutral-current nuclear matrix elements in nucleon matter at densities of 0.08, 0.16 and 0.24 fm$^{-3}$ and proton fractions ranging from 0.2 to 0.5. The correlated states for nucleon matter are obtained by operating on Fermi-gas states by a symmetrized product of pair correlation operators determined from variational calculations with the Argonne v18 and Urbana IX two- and three-nucleon interactions. The squares of the charge current matrix elements are found to be quenched by 20 to 25 % by the short-range correlations in nucleon matter. Most of the quenching is due to spin-isospin correlations induced by the pion exchange interactions which change the isospins and spins of the nucleons. A large part of it can be related to the probability for a spin up proton quasi-particle to be a bare spin up/down proton/neutron. We also calculate the matrix elements of the nuclear Hamiltonian in the same correlated basis. These provide relatively mild effective interactions which give the variational energies in the Hartree-Fock approximation. The calculated two-nucleon effective interaction describes the spin-isospin susceptibilities of nuclear and neutron matter fairly accurately. However $\geq$ 3-body terms are necessary to reproduce the compressibility. All presented results use the simple 2-body cluster approximation to calculate the correlated basis matrix elements.Comment: submitted to PR

Spin-orbit induced backflow in neutron matter with auxiliary field diffusion Monte Carlo

The energy per particle of zero-temperature neutron matter is investigated, with particular emphasis on the role of the $\vec L\cdot\vec S$ interaction. An analysis of the importance of explicit spin--orbit correlations in the description of the system is carried out by the auxiliary field diffusion Monte Carlo method. The improved nodal structure of the guiding function, constructed by explicitly considering these correlations, lowers the energy. The proposed spin--backflow orbitals can conveniently be used also in Green's Function Monte Carlo calculations of light nuclei.Comment: 4 pages, 1 figur

Landau parameters of nuclear matter in the spin and spin-isospin channels

The equation of state of spin and isospin polarized nuclear matter is determined in the framework of the Brueckner theory including three-body forces. The Landau parameters in the spin and spin-isospin sectors are derived as a function of the baryonic density. The results are compared with the Gamow-Teller collective modes. The relevance of $G_0$ and $G_0'$ for neutron stars is shortly discussed, including the magnetic susceptibility and the neutron star cooling.Comment: 2 pages, 2 figures, RevTex4 forma

Many-body theory interpretation of deep inelastic scattering

We analyze data on deep inelastic scattering of electrons from the proton using ideas from standard many-body theory involving {\em bound} constituents subject to {\em interactions}. This leads us to expect, at large three-momentum transfer ${\bf{q}}$, scaling in terms of the variable $\tilde{y}=\nu-{\bf |q|}$. The response at constant ${\bf |q|}$ scales well in this variable. Interaction effects are manifestly displayed in this approach. They are illustrated in two examples.Comment: 10 pages, 4 figure