Momentum distributions in A = 3 and 4 nuclei

Abstract

We develop a general Monte Carlo method to study momentum distributions of nucleons and nucleon clusters in nuclei. The method is used to calculate the momentum distributions of protons and neutrons in A = 3 and 4, d + p amplitudes in 3He, and t + p and d + d amplitudes in 4He nuclei, with improved variational wave functions. The nucleon and d + p momentum distributions in 3He are also calculated from a five-channel Faddeev wave function. The calculations are based on realistic hamiltonians that include the three-nucleon interaction, and give reasonable binding energies and densities for light nuclei and nuclear matter. The calculated proton and d + p momentum distributions in 3He at low k are in good agreement with the results obtained by the Saclay analysis of the electron scattering data in the plane-wave impulse approximation; however, at higher values of k, the calculated momentum distributions are larger. The calculated values of the asymptotic D- to S-wave ratio of the d+n and d+d amplitudes are also in agreement with the values obtained from (d, t) and (d, α) reactions. The number of deuterons is found to be 1.38 and ∼2.4 in A = 3 and 4 nuclei, while the number of tritons in 4He is ∼1.6. This large value of the triton number reflects the large contribution (more than 90% at small k) of the t+p state to the total proton momentum distribution in 4He.