7,926 research outputs found
Renormalization in a Lorentz-violating model and higher-order operators
The renormalization in a Lorentz-breaking scalar-spinor higher-derivative
model involving self-interaction and the Yukawa-like coupling is
studied. We explicitly de- monstrate that the convergence is improved in
comparison with the usual scalar-spinor model, so, the theory is
super-renormalizable, with no divergences beyond four loops. We compute the
one-loop corrections to the propagators for the scalar and fermionic fields and
show that in the presence of higher-order Lorentz invariance violation, the
poles that dominate the physical theory, are driven away from the standard
on-shell pole mass due to radiatively induced lower dimensional operators. The
new operators change the standard gamma-matrix structure of the two-point
functions, introduce large Lorentz-breaking corrections and lead to
modifications in the renormalization conditions of the theory. We found the
physical pole mass in each sector of our model.Comment: 20 pages, 5 figures. New version with modifications in the
renormalized Lagrangian. To be published in EPJ
Dynamical Lorentz and CPT symmetry breaking in a 4D four-fermion model
In a 4D chiral Thirring model we analyse the possibility that radiative
corrections may produce spontaneous breaking of Lorentz and CPT symmetry. By
studying the effective potential, we verified that the chiral current
may assume a nonzero vacuum expectation
value which triggers the Lorentz and CPT violations. Furthermore, by making
fluctuations on the minimum of the potential we dynamically induce a bumblebee
like model containing a Chern-Simons term.Comment: Small modifications in the text and new references added, 12 pages, 4
figures, revtex4. To appear in Phys. Rev.
On the induction of the four-dimensional Lorentz-breaking non-Abelian Chern-Simons action
A four-dimensional Lorentz-breaking non-Abelian Chern-Simons like action is
generated as a one-loop perturbative correction via an appropriate
Lorentz-breaking coupling of the non-Abelian gauge field to the spinor field.
This term is shown to be regularization dependent but nevertheless it can be
found unambiguously in different regularization schemes at zero and finite
temperature.Comment: accepted version in Physical Review
The Low Energy Limit of the Chern-Simons Theory Coupled to Fermions
We study the nonrelativistic limit of the theory of a quantum Chern--Simons
field minimally coupled to Dirac fermions. To get the nonrelativistic effective
Lagrangian one has to incorporate vacuum polarization and anomalous magnetic
moment effects. Besides that, an unsuspected quartic fermionic interaction may
also be induced. As a by product, the method we use to calculate loop diagrams,
separating low and high loop momenta contributions, allows to identify how a
quantum nonrelativistic theory nests in a relativistic one.Comment: 18 pages, 8 figures, Late
On the radiative corrections in the Horava-Lifshitz z=2 QED
We calculate one-loop contributions to the two and three point spinor-vector
functions in z=2 Horava-Lifshitz QED. This allows us to obtain the anomalous
magnetic moment.Comment: 10 pages, minor correction
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