11,115 research outputs found
Renormalization of supersymmetric Yang-Mills theories with soft supersymmetry breaking
The renormalization of supersymmetric Yang-Mills theories with soft
supersymmetry breaking is presented using spurion fields for introducing the
breaking terms. It is proven that renormalization of the fields and parameters
in the classical action yields precisely the correct counterterms to cancel all
divergences. In the course of the construction of higher orders additional
independent parameters appear, but they can be shown to be irrelevant in
physics respects. Thus, the only parameters with influence on physical
amplitudes are the supersymmetric and the well-known soft breaking parameters.Comment: 29 pages, published in The European Physical Journal
Venus and Mars nominal natural environment for advanced manned planetary mission programs
Nominal natural environment values for advanced manned planetary space flights to Venus and Mar
Reinventing spacetime on a dynamical hypersurface
In braneworld models, Space-Time-Matter and other Kaluza-Klein theories, our
spacetime is devised as a four-dimensional hypersurface {\it orthogonal} to the
extra dimension in a five-dimensional bulk. We show that the FRW line element
can be "reinvented" on a dynamical four-dimensional hypersurface, which is {\it
not} orthogonal to the extra dimension, without any internal contradiction.
This hypersurface is selected by the requirement of continuity of the metric
and depends explicitly on the evolution of the extra dimension. The main
difference between the "conventional" FRW, on an orthogonal hypersurface, and
the new one is that the later contains higher-dimensional modifications to the
regular matter density and pressure in 4D. We compare the evolution of the
spacetime in these two interpretations. We find that a wealth of "new" physics
can be derived from a five-dimensional metric if it is interpreted on a
dynamical (non-orthogonal) 4D hypersurface. In particular, in the context of a
well-known cosmological metric in , we construct a FRW model which is
consistent with the late accelerated expansion of the universe, while fitting
simultaneously the observational data for the deceleration parameter. The model
predicts an effective equation of state for the universe, which is consistent
with observations.Comment: References added to the Introduction, and Abstract modified. Accepted
for publication in Mod. Phys. Lett.
Limits on the integration constant of the dark radiation term in Brane Cosmology
We consider the constraints from primordial Helium abundances on the constant
of integration of the dark radiation term of the brane-world generalized
Friedmann equation derived from the Randall-Sundrum Single brane model. We
found that -- using simple, approximate and semianalytical Method -- that the
constant of integration is limited to be between -8.9 and 2.2 which limits the
possible contribution from dark radiation term to be approximately between -27%
to 7% of the background photon energy density.Comment: 8 page
Softly broken supersymmetric Yang-Mills theories: Renormalization and non-renormalization theorems
We present a minimal version for the renormalization of softly broken
Super-Yang-Mills theories using the extended model with a local gauge coupling.
It is shown that the non-renormalization theorems of the case with unbroken
supersymmetry are valid without modifications and that the renormalization of
soft-breaking parameters is completely governed by the renormalization of the
supersymmetric parameters. The symmetry identities in the present context are
peculiar, since the extended model contains two anomalies: the Adler-Bardeen
anomaly of the axial current and an anomaly of supersymmetry in the presence of
the local gauge coupling. From the anomalous symmetries we derive the exact
all-order expressions for the beta functions of the gauge coupling and of the
soft-breaking parameters. They generalize earlier results to arbitrary
normalization conditions and imply the NSVZ expressions for a specific
normalization condition on the coupling.Comment: 24 pages, LaTeX, v2: one reference adde
Affine maps of density matrices
For quantum systems described by finite matrices, linear and affine maps of
matrices are shown to provide equivalent descriptions of evolution of density
matrices for a subsystem caused by unitary Hamiltonian evolution in a larger
system; an affine map can be replaced by a linear map, and a linear map can be
replaced by an affine map. There may be significant advantage in using an
affine map. The linear map is generally not completely positive, but the linear
part of an equivalent affine map can be chosen to be completely positive and
related in the simplest possible way to the unitary Hamiltonian evolution in
the larger system.Comment: 4 pages, title changed, sentence added, reference update
Application of advanced technologies to small, short-haul transport aircraft (STAT)
The benefits of selected advanced technologies for 19 and 30 passenger, short-haul aircraft were identified. Advanced technologies were investigated in four areas: aerodynamics, propulsion, structures, and ride quality. Configuration sensitivity studies were conducted to show design tradeoffs associated with passenger capacity, cabin comfort level, and design field length
Brane Cosmology With Generalized Chaplygin Gas in The Bulk
We find exact solution of the Einstein equations in the context of the brane
world scenario. We have supposed a {generalized chaplygin gas} equation of
state for bulk. This study display a constant energy density and pressure for
bulk in late time. It is shown that our assumptions impose a specific equation
of state on brane. {In this work, we have obtained a decelerate universe in
early time and late time.} In the end, it is shown that under some assumption
we have equation of state of cosmological constant for bulk.Comment: 11 page
Asymmetric radiating brane-world
At high energies on a cosmological brane of Randall-Sundrum type, particle
interactions can produce gravitons that are emitted into the bulk and that can
feed a bulk black hole. We generalize previous investigations of such radiating
brane-worlds by allowing for a breaking of Z_2-symmetry, via different bulk
cosmological constants and different initial black hole masses on either side
of the brane. One of the notable features of asymmetry is a suppression of the
asymptotic level of dark radiation, which means that nucleosynthesis
constraints are easier to satisfy. There are also models where the radiation
escapes to infinity on one or both sides, rather than falling into a black
hole, but these models can have negative energy density on the brane.Comment: sign error in eq. (34) corrected; version to appear Phys. Rev.
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