  The quasi-deuteron model introduced by Levinger is used to explain cross
sections for knocking out high-momentum protons in photo-absorption on nuclei.
This is within a framework we characterize as exhibiting high renormalization
group (RG) resolution. Assuming a one-body reaction operator, the nuclear wave
function must include two-body short-range correlations (SRCs) with
deuteron-like quantum numbers. In a previous paper, we showed that SRC physics
can be naturally accounted for at low RG resolution. Here we describe the
quasi-deuteron model at low RG resolution and determine the Levinger constant,
which is proportional to the ratio of nuclear photo-absorption to that for
photo-disintegration of a deuteron. We extract the Levinger constant based on
the ratio of momentum distributions at high relative momentum. We compute
momentum distributions evolved under similarity RG (SRG) transformations, where
the SRC physics is shifted into the operator as a universal two-body term. The
short-range nature of this operator motivates using local-density
approximations with uncorrelated wave functions in evaluating nuclear matrix
elements, which greatly simplifies the analysis. The operator must be
consistently matched to the RG scale and scheme of the interaction for a
reliable extraction. We apply SRG transformations to different nucleon-nucleon
(NN) interactions and use the deuteron wave functions and Weinberg eigenvalues
to determine approximate matching scales. We predict the Levinger constant for
several NN interactions and a wide range of nuclei comparing to experimental
extractions. The predictions at low RG resolution are in good agreement with
experiment when starting with a hard NN interaction and the initial operator.
Similar agreement is found using soft NN interactions when the additional
two-body operator induced by evolution from hard to soft is included.
