21 research outputs found
Superpropagators for explicitly broken 3D-supersymmetric theories
A systematic algorithm to derive superpropagators in the case of either
explicitly or spontaneously broken supersymmetric three-dimensional theories is
presented. We discuss how the explicit breaking terms that are introduced at
tree-level induce 1-loop radiative corrections to the effective action. We also
point out that the renormalisation effects and the breaking-inducing-breaking
mechanism become more immediate whenever we adopt the shifted superpropagators
discussed in this letter.Comment: 6 pages, LaTex, references added. To appear in Phys.Lett.
Current-Carrying Cosmic Strings in Scalar-Tensor Gravities
We study the modifications on the metric of an isolated self-gravitating
bosonic superconducting cosmic string in a scalar-tensor gravity in the
weak-field approximation. These modifications are induced by an arbitrary
coupling of a massless scalar field to the usual tensorial field in the
gravitational Lagrangian. The metric is derived by means of a matching at the
string radius with a most general static and cylindrically symmetric solution
of the Einstein-Maxwell-scalar field equations. We show that this metric
depends on five parameters which are related to the string's internal structure
and to the solution of the scalar field. We compare our results with those
obtained in the framework of General Relativity.Comment: 23 pages, no figures, LATEX fil
Remarks on the Causality, Unitarity and Supersymmetric Extension of the Lorentz and CPT-Violating Maxwell-Chern-Simons Model
The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here
re-assessed and issues like causality, unitarity, spontaneous gauge-symmetry
breaking are investigated. Moreover, we obtain a minimal extension of such a
system to a supersymmetric environment. We comment on resulting peculiar
self-couplings for the gauge sector, as well as on background contribution for
gaugino masses.Comment: 5 pages, NPB style, talk presented at "Renormalization Group and
Anomalies in Gravity and Cosmology", Ouro Preto, Brazil, March 200
Extending the D'Alembert Solution to Space-Time Modified Riemann-Liouville Fractional Wave Equations
In the realm of complexity, it is argued that adequate modeling of
TeV-physics demands an approach based on fractal operators and fractional
calculus (FC). Non-local theories and memory effects are connected to
complexity and the FC. The non-differentiable nature of the microscopic
dynamics may be connected with time scales. Based on the Modified
Riemann-Liouville definition of fractional derivatives, we have worked out
explicit solutions to a fractional wave equation with suitable initial
conditions to carefully understand the time evolution of classical fields with
a fractional dynamics. First, by considering space-time partial fractional
derivatives of the same order in time and space, a generalized fractional
D'Alembertian is introduced and by means of a transformation of variables to
light-cone coordinates, an explicit analytical solution is obtained. To address
the situation of different orders in the time and space derivatives, we adopt
different approaches, as it will become clear throughout the paper. Aspects
connected to Lorentz symmetry are analyzed in both approaches.Comment: 8 page
Huyghens Principle, Planck Law: Peculiarities in the Behavior of Planar Photons
Huyghens principle and Planck law are studied in Maxwell and
Maxwell-Chern-Simons frameworks in (2+1) dimensions. Contrary to (3+1)
dimensions, massless photons are shown to violate Huyghens principle in planar
world. In addition, we obtain that Planck law is no longer proportional to
, but to the squared frequency, , of the planar photons. We also
briefly discuss possible physical consequences of these results.Comment: 10 pages, no figures. Latex forma
Graviton Excitations and Lorentz-Violating Gravity with Cosmological Constant
Motivated by the interest raised by the problem of Lorenz-symmetry violating
gauge theories in connetion with gravity models, this contribution sets out to
provide a general method to systematically study the excitation spectrum of
gravity actions which include a Lorentz-symmetry breaking Chern-Simons-type
action term for the spin connection. A complete set of spin-type operators is
found which accounts for the (Lorentz) violation parameter to all orders and
graviton propagators are worked out in a number of different situations
A Comment on the Topological Phase for Anti-Particles in a Lorentz-violating environment
Recently, a scheme to analyse topological phases in Quantum Mechanics by
means of the non-relativistic limit of fermions non-minimally coupled to a
Lorentz-breaking background has been proposed. In this letter, we show that the
fixed background, responsible for the Lorentz-symmetry violation, may induce
opposite Aharonov-Casher phases for a particle and its corresponding
antiparticle. We then argue that such a difference may be used to investigate
the asymmetry for particle/anti-particle as well as to propose bounds on the
associated Lorentz-symmetry violating parameters.Comment: 4 pages - A published versio
N=1 Supersymetric Quantum Mechanics in a Scenario with Lorentz-Symmetry Violation
We show in this paper that the dynamics of a non-relativistic particle with
spin, coupled to an external electromagnetic field and to a background that
breaks Lorentz symmetry, is naturally endowed with an N=1-supersymmetry. This
result is achieved in a superspace approach where the particle coordinates and
the spin degrees of freedom are components of the same supermultiplet.Comment: 6 pages, no figure
Consequences of vacuum polarization on electromagnetic waves in a Lorentz-symmetry breaking scenario
The propagation of electromagnetic waves in a Lorentz-symmetry violating
scenario where there is a region of polarized vacuum is studied. It turns out
that the photon field acquires an interesting polarization state, possibly
useful to set up upper bounds in Lorentz-violating models at laboratory scales.Comment: Latex, 4 pages. To appear in PL
Cosmic String in the Supersymmetric CSKR Theory
We study a cosmic string solution of an N=1-supersymmetric version of the
Cremmer-Scherk-Kalb-Ramond (CSKR) Lagrangian coupled to a vector superfield by
means of a topological mass term. The 2-form gauge potential is proposed to
couple non-minimally to matter, here described by a chiral scalar superfield.
The important outcome is that supersymmetry is kept exact both in the core and
in the exterior region of the string. We contemplate the bosonic configurations
and it can be checked that the solutions saturate the Bogomolnyi bound. A
glimpse on the fermionic zero modes is also given.Comment: 14 pages, LaTeX, presented at the XXI "Encontro Nacional de Fisica de
Particulas e Campos", Sao Lourenco, MG, Brazil, with zero modes adde