Multiple gaps and superfluid density from interband pairing in a four-band model of the iron oxypnictides

We study a four-band model for the iron oxypnictides, in which the superconducting properties are assumed to be determined by the interband coupling between holelike and electronlike Fermi sheets. We show that reasonable parameters can account for the angle-resolved photoemission spectra, showing multiple gaps in Ba1-xKxFe2As2, and for the temperature dependence of the superfluid density. At the same time, the zero-temperature value of the superfluid density shows a conventional scaling with the number of carriers.