Anisotropic Superconducting Gap in a Multiorbital t-J$_1$-J$_2$ Model for Iron Pnictides

We study the anisotropy of the superconducting gaps in the iron pnictides within a five-orbital t-J$_1$-J$_2$ model. We show that the interplay between the multiorbital nature and the magnetic frustration can give rise to an anisotropic superconducting gap with the $A_{1g}$ pairing symmetry. We have also calculated the dynamical spin susceptibility in the superconducting state, and find that the anisotropic gap structure affects the spin dynamics by showing two resonance peaks. We further discuss the connections between our results and recent ARPES and inelastic neutron scattering measurements.