  Nuclear short-range correlations (SRC) typically manifest themselves in the
tail parts of the single-nucleon momentum distributions. We propose an
approximate practical method for computing those SRC contributions to the
high-momentum parts. The framework adopted in this work is applicable
throughout the nuclear mass table and corrects mean-field models for central,
spin-isospin and tensor correlations by shifting the complexity induced by the
SRC from the wave functions to the operators. It is argued that the expansion
of these modified operators can be truncated to a low order. The proposed model
can generate the SRC-related high-momentum tail of the single-nucleon momentum
distribution. These are dominated by correlation operators acting on mean-field
pairs with vanishing relative radial and angular-momentum quantum numbers. The
proposed method explains the dominant role of proton-neutron pairs in
generating the SRC and accounts for the magnitude and mass dependence of SRC as
probed in inclusive electron scattering. It also provides predictions for the
ratio of the amount of correlated proton-proton to proton-neutron pairs which
are in line with the observations. In asymmetric nuclei, the correlations make
the average kinetic energy for the minority nucleons larger than for the
majority nucleons.
