27,995 research outputs found
On the -Dirac Oscillator revisited
This Letter is based on the -Dirac equation, derived from the
-Poincar\'{e}-Hopf algebra. It is shown that the -Dirac
equation preserves parity while breaks charge conjugation and time reversal
symmetries. Introducing the Dirac oscillator prescription,
, in the -Dirac
equation, one obtains the -Dirac oscillator. Using a decomposition in
terms of spin angular functions, one achieves the deformed radial equations,
with the associated deformed energy eigenvalues and eigenfunctions. The
deformation parameter breaks the infinite degeneracy of the Dirac oscillator.
In the case where , one recovers the energy eigenvalues and
eigenfunctions of the Dirac oscillator.Comment: 5 pages, no figures, accepted for publication in Physics Letters
Maxwell-Chern-Simons vortices in a CPT-odd Lorentz-violating Higgs Electrodynamics
We have studied BPS vortices in a CPT-odd and Lorentz-violating
Maxwell-Chern-Simons-Higgs (MCSH) electrodynamics attained from the dimensional
reduction of the Carroll-Field-Jackiw-Higgs model. The Lorentz-violating
parameter induces a pronounced behavior at origin (for the magnetic/electric
fields and energy density) which is absent in the MCSH vortices. For some
combination of the Lorentz-violating coefficients there always exist a
sufficiently large winding number such that for all
the magnetic field flips its signal, yielding two well defined regions with
opposite magnetic flux. However, the total magnetic flux remains quantized and
proportional to the winding number.Comment: Revtex style, 8 page
Probing wrong-sign Yukawa couplings at the LHC and a future linear collider
We consider the two-Higgs-doublet model as a framework in which to evaluate
the viability of scenarios in which the sign of the coupling of the observed
Higgs boson to down-type fermions (in particular, -quark pairs) is opposite
to that of the Standard Model (SM), while at the same time all other tree-level
couplings are close to the SM values. We show that, whereas such a scenario is
consistent with current LHC observations, both future running at the LHC and a
future linear collider could determine the sign of the Higgs coupling
to -quark pairs. Discrimination is possible for two reasons. First, the
interference between the -quark and the -quark loop contributions to the
coupling changes sign. Second, the charged-Higgs loop contribution to the
coupling is large and fairly constant up to the largest
charged-Higgs mass allowed by tree-level unitarity bounds when the -quark
Yukawa coupling has the opposite sign from that of the SM (the change in sign
of the interference terms between the -quark loop and the and loops
having negligible impact).Comment: 28 pages, 21 figure
Effects of a CPT-even and Lorentz-violating nonminimal coupling on the electron-positron scattering
We propose a new \emph{CPT}-even and Lorentz-violating nonminimal coupling
between fermions and Abelian gauge fields involving the CPT-even tensor
of the standard model extension. We thus
investigate its effects on the cross section of the electron-positron
scattering by analyzing the process .
Such a study was performed for the parity-odd and parity-even nonbirefringent
components of the Lorentz-violating tensor.
Finally, by using experimental data available in the literature, we have
imposed upper bounds as tight as on the magnitude of the
CPT-even and Lorentz-violating parameters while nonminimally coupled.Comment: LaTeX2e, 06 pages, 01 figure
Modelling of epitaxial film growth with a Ehrlich-Schwoebel barrier dependent on the step height
The formation of mounded surfaces in epitaxial growth is attributed to the
presence of barriers against interlayer diffusion in the terrace edges, known
as Ehrlich-Schwoebel (ES) barriers. We investigate a model for epitaxial growth
using a ES barrier explicitly dependent on the step height. Our model has an
intrinsic topological step barrier even in the absence of an explicit ES
barrier. We show that mounded morphologies can be obtained even for a small
barrier while a self-affine growth, consistent with the Villain-Lai-Das Sarma
equation, is observed in absence of an explicit step barrier. The mounded
surfaces are described by a super-roughness dynamical scaling characterized by
locally smooth (faceted) surfaces and a global roughness exponent .
The thin film limit is featured by surfaces with self-assembled
three-dimensional structures having an aspect ratio (height/width) that may
increase or decrease with temperature depending on the strength of step
barrier.Comment: To appear in J. Phys. Cond. Matter; 3 movies as supplementary
materia
Radiative generation of the CPT-even gauge term of the SME from a dimension-five nonminimal coupling term
In this letter we show for the first time that the usual CPT-even gauge term
of the standard model extension (SME) can be radiatively generated, in a gauge
invariant level, in the context of a modified QED endowed with a dimension-five
nonminimal coupling term recently proposed in the literature. As a consequence,
the existing upper bounds on the coefficients of the tensor can be
used improve the bounds on the magnitude of the nonminimal coupling,
by the factors or The nonminimal coupling
also generates higher-order derivative contributions to the gauge field
effective action quadratic terms.Comment: Revtex style, two columns, 6 pages, revised final version to be
published in the Physics Letters B (2013
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