Quasiparticle dephasing time in disordered d-wave superconductors

We evaluate the low-temperature cutoff for quantum interference 1∕τφ induced in a d-wave superconductor by diffusion-enhanced quasiparticle interactions in the presence of disorder. We carry out our analysis in the framework of the nonlinear σ model, which allows a direct calculation of 1∕τφ, as the mass of the transverse modes of the theory. Only the triplet amplitude in the particle-hole channel and the Cooper amplitude with is pairing symmetry contribute to 1∕τφ. We discuss the possible relevance of our results to the present disagreement between thermal transport data in cuprates and the localization theory for d-wave quasiparticles