Aplicações de métodos perturbativos de TQC em modelos de baixa dimensionalidade e matéria condensada

Abstract

Given the Implicit Regularization's success to separate and analyse spurious arbitrariness, which arise while treating divergent integrals, we proposed to apply this method in three distinct cases. In the rst, we compute the Coulomb correction C to the a.c. conductivity of interacting massless Dirac particles in graphene using the polarization tensor approach. Arbitrary parameters are xed on physical grounds exploiting only spatial O(2) rotational invariance of the model which amounts to transversality of the polarization tensor. Consequently C is unequivocally determined to be (196)=12 within this e ective model. In the second case, we study the QED3 and the consequences of momentum routing invariance for the violation of the theory's parity symmetry. In the third case, we consider an e ective model formed by usual QED4 with the addition of a nonminimal Lorentz violating interaction (proportional to a xed 4-vector b). We show that gauge invariance from usual QED, considered as a limit of the model for b ! 0, plays an important role in the discussion of the radiatively induced Lorentz violating terms at one-loop order.