Two-nucleon spectral function in infinite nuclear matter

The two-nucleon spectral function in nuclear matter is studied using correlated basis function perturbation theory, including central and tensor correlations produced by a realistic Hamiltonian. The factorization property of the two-nucleon momentum distribution into the product of the two single nucleon distributions shows up in an analogous property of the spectral function. The correlated model yields a two-hole contribution quenched with respect to the Fermi gas model, while the peaks acquire a quasiparticle width that vanishes as the two momenta approach the Fermi momentum k(F). In addition, three-hole one-particle and more complicated intermediate states give rise to a background, spread out in energy and absent in the uncorrelated models. The possible connections with one- and two-nucleon emission processes are briefly discussed.