QED 3 and two-dimensional superconductivity without parity violation

We investigate a recently proposed parity-invariant model of two-dimensional superconductivity. The model consists of two-species of fermions coupled with opposite sign to an abelian gauge field and is closely related to QED ₃. The first part of the paper is devoted to a detailed analysis of the relevant properties of QED ₃. In particular we study the dynamical generation of a parity-conserving fermion mass and the finite-temperature symmetry restoration transition. We show how the parity-invariant model arises as an effective long-wavelength theory of the dynamics of holes in a two-dimensional quantum antiferromagnet. The model exhibits type-II superconductivity without parity or time-reversal symmetry violation, a high value of 2 Δ/ k_BT_c, flux quantization with quantum hc/2 e and a two-dimensional Meissner effect. We discuss the possible relevance of this model to the high- T_c superconductors