Solution of mass/gap equations for strong velocity anisotropy in the QED3 theory of underdoped cuprates

Abstract

The low-lying excitations at the nodes of the d-wave gap in the normal state for underdoped cuprates, close to the superconducting phase transition, may be described by an effective QED3 theory. There are three characteristic velocities: v_F, v_Delta and c. For v_Delta=v_F=c, the model reduces to N-flavour QED3. Here, in the isotropic limit, for N 100. However, we argue that N_c=N_0c, when we go beyond the approximations used to derive our mass gap equations. We expect, though, that our solution for N=2 is roughly correct, at low momentum, for large enough anisotropies. Implications and possible extensions to this work are also discussed.