Universal momentum distributions and short-range nucleon correlations

The problem of constructing universal two-nucleon momentum distributions for main $NN$-configurations $^1S_0$ and $^3S_1$-$^3D_1$ used to describe short-range nucleon correlations in nuclei has been studied. A new method for calculating such distributions has been proposed, and their properties have been studied. As illustrations, calculations for several modern realistic $NN$ potentials, including non-nucleon degrees of freedom, have been provided. A new characteristic that determines the ratio of the fractions of high-momentum components for spin-singlet and spin-triplet $NN$ distributions at low energies, which can be useful for comparative evaluation of the isospin dependence of short-range correlations in calculations with different $NN$ interaction potentials, has been proposed.