We formulate a minimal model of point contact Andreev reflection spectroscopy
of a normal- metal/multiband superconductor interface. The theory generalizes
the Blonder-Tinkham-Klapwijk (BTK) formulation to a multiband superconductor
and it is based on the quantum waveguides theory. The proposed approach allows
an analytic evaluation of the Andreev and normal reflection coefficients and
thus is suitable for a data fitting of point contact experiments. The obtained
differential conductance curves present distinctive features similar to the
ones measured in the experiments on multiband systems, like the iron-based
pnictides and the MgB2.Comment: 5 pages, 4 figure
