2,064 research outputs found
A Classical Solution in Six-dimensional Gauge Theory with Higher Derivative Coupling
We show that the spin connection of the standard metric on a six-dimensional
sphere gives an exact solution to the generalized self-dual equations suggested
by Tchrakian some years ago. We work on an SO(6) gauge theory with a
higher-derivative coupling term. The model consists of vector fields only. The
pseudo-energy is bound from below by a topological charge which is proportional
to the winding number of spatial S^5 around the internal space SO(6). The fifth
homotopy group of SO(6) is, indeed, Z. The coupling constant of higher
derivative term is quadratic in the radius of the underlying space S^6.Comment: 7 pages, comments and a reference added, typos correcte
Second order brane cosmology with radion stabilization
We study cosmology in the five-dimensional Randall-Sundrum brane-world with a
stabilizing effective potential for the radion and matter localized on the
branes. The analysis is performed by employing a perturbative expansion in the
ratio rho/V between the matter energy density on the branes and the brane
tensions around the static Randall-Sundrum solution (which has rho=0 and brane
tensions +-V). This approach ensures that the matter evolves adiabatically and
allows us to find approximate solutions to second order in \rho/V. Some
particular cases are then analyzed in details.Comment: 17 pages, RevTeX4, 4 figures, final version to appear in Phys. Rev.
Quantum effects from a purely geometrical relativity theory
A purely geometrical relativity theory results from a construction that
produces from three-dimensional space a happy unification of Kaluza's
five-dimensional theory and Weyl's conformal theory. The theory can provide
geometrical explanations for the following observed phenomena, among others:
(a) lifetimes of elementary particles of lengths inversely proportional to
their rest masses; (b) the equality of charge magnitude among all charged
particles interacting at an event; (c) the propensity of electrons in atoms to
be seen in discretely spaced orbits; and (d) `quantum jumps' between those
orbits. This suggests the possibility that the theory can provide a
deterministic underpinning of quantum mechanics like that provided to
thermodynamics by the molecular theory of gases.Comment: 7 pages, LaTeX jpconf.cls (Institute of Physics Publishing), 6
Encapsulated PostScript figures (Fig. 6 is 1.8M uncompressed); Presented at
VI Mexican School on Gravitation and Mathematical Physics "Approaches to
Quantum Gravity
Massive color-octet bosons and the charge asymmetries of top quarks at hadron colliders
Several models predict the existence of heavy colored resonances decaying to
top quarks in the TeV energy range that might be discovered at the LHC. In some
of those models, moreover, a sizable charge asymmetry of top versus antitop
quarks might be generated. The detection of these exotic resonances, however,
requires selecting data samples where the top and the antitop quarks are highly
boosted, which is experimentally very challenging. We asses that the
measurement of the top quark charge asymmetry at the LHC is very sensitive to
the existence of excited states of the gluon with axial-vector couplings to
quarks. We use a toy model with general flavour independent couplings, and show
that a signal can be detected with relatively not too energetic top and antitop
quarks. We also compare the results with the asymmetry predicted by QCD, and
show that its highest statistical significance is achieved with data samples of
top-antitop quark pairs of low invariant masses.Comment: 20 page
Analytic pulse design for selective population transfer in many-level quantum systems: maximizing amplitude of population oscillations
State selective preparation and manipulation of discrete-level quantum
systems such as atoms, molecules or quantum dots is a the ultimate tool for
many diverse fields such as laser control of chemical reactions, atom optics,
high-precision metrology and quantum computing. Rabi oscillations are one of
the simplest, yet potentially quite useful mechanisms for achieving such
manipulation. Rabi theory establishes that in the two-level systems resonant
drive leads to the periodic and complete population oscillations between the
two system levels. In this paper an analytic optimization algorithm for
producing Rabi-like oscillations in the general discrete many-level quantum
systems is presented.Comment: Published in Phys.Rev.A. This is the final published versio
Five-Dimensional Unification of the Cosmological Constant and the Photon Mass
Using a non-Riemannian geometry that is adapted to the 4+1 decomposition of
space-time in Kaluza-Klein theory, the translational part of the connection
form is related to the electromagnetic vector potential and a Stueckelberg
scalar. The consideration of a five-dimensional gravitational action functional
that shares the symmetries of the chosen geometry leads to a unification of the
four-dimensional cosmological term and a mass term for the vector potential.Comment: 8 pages, LaTe
Limits of space-times in five dimensions and their relation to the Segre Types
A limiting diagram for the Segre classification in 5-dimensional space-times
is obtained, extending a recent work on limits of the energy-momentum tensor in
general relativity. Some of Geroch's results on limits of space-times in
general relativity are also extended to the context of five-dimensional
Kaluza-Klein space-times.Comment: Late
Boosted Top Quark Signals for Heavy Vector Boson Excitations in a Universal Extra Dimension Model
In view of the fact that the Kaluza-Klein (KK) modes in a model with
a Universal Extra Dimension (UED), could mimic supersymmetry signatures at the
LHC, it is necessary to look for the KK modes, which have no analogues
in supersymmetry. We discuss the possibility of searching for heavy
vector boson resonances -- especially the -- through their decays to a
highly-boosted top quark-antiquark pair using recently-developed top-jet
tagging techniques in the hadronic channel. It is shown that signals
from the gluon resonance are as efficient a discovery mode at the LHC
as dilepton channels from the and resonances.Comment: 22 pages, 8 embedded figure
A Note on Segre Types of Second Order Symmetric Tensors in 5-D Brane-world Cosmology
Recent developments in string theory suggest that there might exist extra
spatial dimensions, which are not small nor compact. The framework of most
brane cosmological models is that in which the matter fields are confined on a
brane-world embedded in five dimensions (the bulk). Motivated by this we
reexamine the classification of the second order symmetric tensors in 5--D, and
prove two theorems which collect together some basic results on the algebraic
structure of these tensors in 5-dimensional space-times. We also briefly
indicate how one can obtain, by induction, the classification of symmetric
two-tensors (and the corresponding canonical forms) on n-dimensional spaces
from the classification on 4-dimensional spaces. This is important in the
context of 11--D supergravity and 10--D superstrings.Comment: 12 pages, to appear in Mod. Phys. Lett. A (2003) in the present for
Particle Physics Probes Of Extra Spacetime Dimensions
The possibility that spacetime is extended beyond the familiar 3+1-dimensions
has intrigued physicists for a century. Indeed, the consequences of a
dimensionally richer spacetime would be profound. Recently, new theories with
higher dimensional spacetimes have been developed to resolve the hierarchy
problem in particle physics. These scenarios make distinct predictions which
allow for experiment to probe the existence of extra dimensions in new ways. We
review the conceptual framework of these scenarios, their implications in
collider and short-range gravity experiments, their astrophysical and
cosmological effects, as well as the constraints placed on these models from
present data.Comment: Submitted to Annual Review of Nuclear and Particle Science, 29 page
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