19,121 research outputs found
A Next-to-Minimal Supersymmetric Model of Hybrid Inflation
We propose a model of inflation based on a simple variant of the NMSSM,
called NMSSM, where the additional singlet plays the role of the
inflaton in hybrid (or inverted hybrid) type models. As in the original NMSSM,
the NMSSM solves the problem of the MSSM via the VEV of a gauge
singlet , but unlike the NMSSM does not suffer from domain wall problems
since the offending symmetry is replaced by an approximate Peccei-Quinn
symmetry which also solves the strong CP problem, and leads to an invisible
axion with interesting cosmological consequences. The PQ symmetry may arise
from a superstring model with an exact discrete symmetry after
compactification. The model predicts a spectral index to one part in
.Comment: 17 pages, Latex; note added, accepted for Phys. Lett.
Dynamical light vector mesons in low-energy scattering of Goldstone bosons
We present a study of Goldstone boson scattering based on the flavor SU(3)
chiral Lagrangian formulated with vector mesons in the tensor field
representation. A coupled-channel channel computation is confronted with the
empirical s- and p-wave phase shifts, where good agreement with the data set is
obtained up to about 1.2 GeV. There are two relevant free parameters only, the
chiral limit value of the pion decay constant and the coupling constant
characterizing the decay of the rho meson into a pair of pions. We apply a
recently suggested approach that implements constraints from micro- causality
and coupled-channel unitarity. Generalized potentials are obtained from the
chiral Lagrangian and are expanded in terms of suitably constructed conformal
variables. The partial-wave scattering amplitudes are defined as solutions of
non-linear integral equations that are solved by means of an N/D ansatz.Comment: 15 pages, 8 figures, typos corrected, accepted for publication in
Physics Letters
Selective Transparence of Single-Mode Waveguides with Surface Scattering
A random surface scattering in a one-mode waveguide is studied in the case
when the surface profile has long-range correlations along the waveguide.
Analytical treatment of this problem shows that with a proper choice of the
surface, one can arrange any desired combination of transparent and
non-transparent frequency windows. We suggest a method to find such profiles,
and demonstrate its effectiveness by making use of direct numerical
simulations.Comment: RevTex, 3 pages including 2 ps-figure
The first confirmation of V-type asteroids among the Mars crosser population
The Mars crossing region constitutes a path to deliver asteroids from the
Inner Main Belt to the Earth crossing space. While both the Inner Main Belt and
the population of Earth crossing asteroids contains a significant fraction of
asteroids belonging to the V taxonomic class, only two of such V-type asteroids
has been detected in the Mars crossing region up to now. In this work, we
searched for asteroids belonging to the V class among the population of Mars
crossing asteroids, in order to support alternative paths to the delivery of
this bodies into the Earth crossing region. We selected 18 candidate V-type
asteroids in the Mars crossing region using observations contained in the Sloan
Digital Sky Survey Moving Objects Catalog. Then, we observed 4 of these
candidates to take their visible spectra using the Southern Astrophysical
Research Telescope (SOAR). We also performed the numerical simulation of the
orbital evolution of the observed asteroids. We confirmed that 3 of the
observed asteroids belong to the V class, and one of these may follow a path
that drives it to an Earth collision in some tens of million years
F-term Hybrid Inflation in Effective Supergravity Theories
We show that the effective low energy supergravity theories which result from a generic string theory can provide a promising framework for models of hybrid inflation in which the potential energy which drives inflation originates from the F-term of the effective supergravity theory. In the class of models considered the inflaton is protected from receiving mass during inflation by a Heisenberg symmetry and the potential during inflation takes the positive definite form , which allows the possibility that . We discuss a toy example where this is realised, then describe the application of this result to realistic models focusing on a particular example in which the problem and the strong CP-problem are addressed
Onset of Delocalization in Quasi-1D Waveguides with Correlated Surface Disorder
We present first analytical results on transport properties of many-mode
waveguides with rough surfaces having long-range correlations. We show that
propagation of waves through such waveguides reveals a quite unexpected
phenomena of a complete transparency for a subset of propagating modes. These
modes do not interact with each other and effectively can be described by the
theory of 1D transport with correlated disorder. We also found that with a
proper choice of model parameters one can arrange a perfect transparency of
waveguides inside a given window of energy of incoming waves. The results may
be important in view of experimental realizations of a selective transport in
application to both waveguides and electron/optic nanodevices.Comment: RevTex, 4 pages, no figures, few references are adde
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