Velocity anisotropy and the antiferromagnetic instability in the QED3 theory of underdoped cuprates -: art. no. 094512

We consider the effective 2+1 dimensional electrodynamics (QED(3)) of low-energy quasiparticles coupled to fluctuating vortex loops in the d-wave superconductor, with the velocity (Dirac) anisotropy v(F)/v(Delta)not equal1. This theory should be relevant to the quantum superconductor-insulator transition in underdoped cuprates. Working in the customary large-N approximation, we find that weak anisotropy is a marginally irrelevant perturbation to the Lorentz invariant QED(3), and that the critical number N-c of Dirac fields below which the theory suffers the antiferromagnetic (chiral) instability stays the same.