We investigate how the Unitary Correlation Operator Method (UCOM), developed
to explicitly describe the strong short-range central and tensor correlations
present in the nuclear many-body system, relates to the Similarity
Renormalization Group (SRG), a method to band-diagonalize Hamiltonians by
continuous unitary transformations. We demonstrate how the structure of the
UCOM transformation, originally motivated from the physically intuitive picture
of correlations in coordinate space, arises naturally from the SRG flow
equation. Apart from formal considerations we show that the momentum space
matrix elements of the effective interactions obtained in both schemes agree
extremely well.Comment: 5 pages, 2 figures, using REVTEX4; v2: references adde
