Theoretical study of the radiative capture reactions H-2(n,gamma)H-3 and H-2(p,gamma)He-3 at low energies

Correlated hyperspherical harmonics wave functions with Delta-isobar admixtures obtained from realistic interactions are used to study the thermal neutron radiative capture on deuterium, and the H-2((p) over right arrow,gamma)He-3 and P((d) over right arrow,gamma)He-3 reactions in the center of mass energy range 0-100 keV. The nuclear electromagnetic current includes one- and two-body components. Results for the H-2((n) over right arrow,gamma)(3) cross section and photon polarization parameter, as well as for the energy dependence of the astrophysical factor and angular distributions of the differential cross section, vector and tensor analyzing powers, and photon linear polarization coefficient of the 2H((p) over right arrow,gamma)He-3 and p((d) over right arrow,gamma)He-3 reactions are reported. Large effects due to two-body currents, in particular the long-range ones associated with the tensor component of the nucleon-nucleon interaction, are observed in the photon polarization parameter and vector analyzing power. Good quantitative agreement between theory and experiment is found for all observables; with the exception of the vector analyzing power for which the calculated values underestimate the data by about 30%.