  We study the zero-bias conductance through the system of two quantum dots,
one of which is embedded directly between the source and drain electrodes,
while the second dot is side-coupled to the first one through a tunneling
junction. Modeling the system using the two-impurity Anderson model, we compute
the temperature-dependence of the conductance in various parameter regimes
using the numerical renormalization group. We consider the non-interacting
case, where we study the extent of the departure from the conventional Fano
resonance line shape at finite temperatures, and the case where the embedded
and/or the side-coupled quantum dot is interacting, where we study the
consequences of the coexistence of the Kondo and Fano effects. If the
side-coupled dot is very weakly interacting, the occupancy changes by two when
the on-site energy crosses the Fermi level and a Fano-resonance-like shape is
observed. If the interaction on the side-coupled dot is sizeable, the occupancy
changes only by one and a very different line-shape results, which is strongly
and characteristically temperature dependent. These results suggest an
intriguing alternative interpretation of the recent experimental results study
of the transport properties of the side-coupled double quantum dot [Sasaki et
al., Phys. Rev. Lett. 103, 266806 (2009)]: the observed Fano-like conductance
anti-resonance may, in fact, result from the two-stage Kondo effect in the
regime where the experimental temperature is between the higher and the lower
Kondo temperature.
