22,287 research outputs found
Lorentz-violating nonminimal coupling contributions in mesonic hydrogen atoms and generation of photon higher-order derivative terms
We have studied the contributions of Lorentz-violating CPT-odd and CPT-even
nonminimal couplings to the energy spectrum of the mesonic hydrogen and the
higher-order radiative corrections to the effective action of the photon sector
of a Lorentz-violating version of the scalar electrodynamics. By considering
the complex scalar field describes charged mesons (pion or kaon), the
non-relativistic limit of the model allows to attain upper-bounds by analyzing
its contribution to the mesonic hydrogen energy. By using the experimental data
for the strong correction shift and the pure QED transitions , the best upper-bound for the CPT-odd coupling is
and for the CPT-even one is
. Besides, the CPT-odd radiative correction to the
photon action is a dimension-5 operator which looks like a higher-order
Carroll-Field-Jackiw term. The CPT-even radiative contribution to the photon
effective action is a dimension-6 operator which would be a higher-order
derivative version of the minimal CPT-even term of the standard model
extension
Non-Linear Effects in Resonant Tunneling; Bistabilities and Self-Sustained Oscillating Currents
We study non-linear phenomena in double barrier heterostructures. Systems in
3D under the effect of an external magnetic field along the current and 1D
systems are analyzed. Non-linearities are reflected in the I-V characteristic
curve as bistabilities, instabilities and time dependent oscillations of the
currents. The nature of the non-linear behavior depends upon the parameters
that define the system.Comment: 3 pages, 2 figures, accepted for publication in Superlattices and
Microstructure
Inverse type II seesaw mechanism and its signature at the LHC and ILC
The advent of the LHC, and the proposal of building future colliders as the
ILC, both programmed to explore new physics at the TeV scale, justifies the
recent interest in studying all kind of seesaw mechanisms whose signature lies
on such energy scale. The natural candidate for this kind of seesaw mechanism
is the inverse one. The conventional inverse seesaw mechanism is implemented in
an arrangement involving six new heavy neutrinos in addition to the three
standard ones. In this paper we develop the inverse seesaw mechanism based on
Higgs triplet model and probe its signature at the LHC and ILC. We argue that
the conjoint analysis of the LHC together with the ILC may confirm the
mechanism and, perhaps, infer the hierarchy of the neutrino masses.Comment: 24 pages, 22 figure
Inspection and diagnosis tests for structural safety evaluation: A case study
Diagnosis and assessment of existing structures is a developing area due to the appearance of a high number of building defects, structural and non-structural deterioration and precocious loss of quality, and, consequently, lower expected durability. With the aim of verifying the viability of rehabilitation or the need to demolish an existing fifteen year old parking building, several inspections and diagnostic non-destructive and destructive testing, visual inspection, were carried out to evaluate the structural safety conditions
A Direct Multigrid Poisson Solver for Oct-Tree Adaptive Meshes
We describe a finite-volume method for solving the Poisson equation on
oct-tree adaptive meshes using direct solvers for individual mesh blocks. The
method is a modified version of the method presented by Huang and Greengard
(2000), which works with finite-difference meshes and does not allow for shared
boundaries between refined patches. Our algorithm is implemented within the
FLASH code framework and makes use of the PARAMESH library, permitting
efficient use of parallel computers. We describe the algorithm and present test
results that demonstrate its accuracy.Comment: 10 pages, 6 figures, accepted by the Astrophysical Journal; minor
revisions in response to referee's comments; added char
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