  The Andreev transport properties of double quantum dot based Cooper pair
splitters with one superconducting and two normal leads are studied
theoretically in the Kondo regime. The influence of the superconducting pairing
correlations on the local density of states, Andreev transmission coefficient
and Cooper pair splitting efficiency is thoroughly analyzed. It is shown that
finite superconducting pairing potential quickly suppresses the SU(2) Kondo
effect, which can however reemerge for relatively large values of coupling to
superconductor. In the SU(4) Kondo regime, a crossover from the SU(4) to the
SU(2) Kondo state is found as the coupling to superconductor is enhanced. The
analysis is performed by means of the density-matrix numerical renormalization
group method.
