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Interactions between a massless tensor field with the mixed symmetry of the Riemann tensor and a massless vector field
Consistent couplings between a massless tensor field with the mixed symmetry
of the Riemann tensor and a massless vector field are analyzed in the framework
of Lagrangian BRST cohomology. Under the assumptions on smoothness, locality,
Lorentz covariance, and Poincare invariance of the deformations, combined with
the requirement that the interacting Lagrangian is at most second-order
derivative, it is proved that there are no consistent cross-interactions
between a single massless tensor field with the mixed symmetry of the Riemann
tensor and one massless vector field.Comment: LaTeX, 24 page
Effects of extended impurity perturbation in d-wave superconductor
We describe the effects of electronic perturbation distributed on nearest
neighbor sites to the impurity center in a planar \textit{d}-wave
superconductor, in approximation of circular Fermi surface. Alike the behavior
previously reported for point-like perturbation and square Fermi surface, the
quasiparticle density of states can display a resonance
inside the gap (and very weak features from low symmetry representations of
non-local perturbation) and asymptotically vanishes at as
. The local suppression of SC order parameter
in this model is found to be somewhat weaker than for an equivalent point-like
(non-magnetic) perturbation and much weaker than for a spin-dependent
(extended) perturbation.Comment: 7 pages, 5 figures, some minor typos and the curves in Fig. 5
correcte
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