  We investigate the Fano-type spectroscopic lineshapes of the T-shape double
quantum dot coupled between the conducting and superconducting electrodes and
analyze their stability on a decoherence. Because of the proximity effect the
quantum interference patterns appear simultaneously at +/- epsilon_2, where
epsilon_2 is an energy of the side-attached quantum dot. We find that
decoherence gradually suppresses both such interferometric structures. We also
show that at low temperatures another tiny Fano-type structure can be induced
upon forming the Kondo state on the side-coupled quantum dot due to its
coupling to the floating lead.
