529 research outputs found
Conformal Dynamics of 0-Branes
We investigate the dynamics of dilatonic D-dimensional 0-branes in the
near-horizon regime. The theory is given in a twofold form: two-dimensional
dilaton gravity and nonlinear sigma model. Using asymptotic symmetries, duality
relations, and sigma model techniques we find that the theory has three
conformal points which correspond to (a) the asymptotic (Anti-de Sitter) region
of the two-dimensional spacetime, (b) the horizon of the black hole, and (c)
the infinite limit of the coupling parameter. We show that the conformal
symmetry is perturbatively preserved at one-loop, identify the corresponding
conformal field theories, and calculate the associated central charges.
Finally, we use the conformal field theories to explain the thermodynamical
properties of the two-dimensional black holes.Comment: 22 pages, LaTex fil
An iterative algorithmic UAV path optimization process for Structure-for-Motion modelling
The use of unmanned aerial vehicles (UAVs) for 3D reconstruction through photogrammetry has gained significant attention in recent years. With the advancement of technology and the availability of affordable drones with high-resolution cameras, capturing aerial images for creating detailed 3D models has become more accessible, however, UAV survey flight planning still presents challenges. The planning stage is essential in aerial photogrammetry as it sets the foundation for efficient and accurate surveying. Proper predictive planning ensures a smooth workflow on site, generating high-quality datasets for reconstruction while minimizing the need for repeat surveys. This approach not only reduces costs but also mitigates potential errors and delays during the survey process. Within the presented frame of reference, the present study explores the use of UAVs for 3D reconstruction through photogrammetry, focusing on optimizing flight paths and view planning. It addresses challenges such as safety, navigation, and image dataset optimization. The study presents the current advancement of custom parametric workflow developed in Rhino/Grasshopper. The workflow is targeted for average users, aiming to simplify the process and integrate it with architectural and planning workflows. The approach involves four algorithms, including proxy model generation, visibility analysis, path generation, and camera position estimation. The iterative process enhances precision through progressive refinement of the proxy model, offering potential for predictive modelling and effective photogrammetry utilization in UAV planning. Further research and testing are needed to validate real-world performance
Minisuperspace Models in M-theory
We derive the full canonical formulation of the bosonic sector of
11-dimensional supergravity, and explicitly present the constraint algebra. We
then compactify M-theory on a warped product of homogeneous spaces of constant
curvature, and construct a minisuperspace of scale factors. First classical
behaviour of the minisuperspace system is analysed, and then a quantum theory
is constructed. It turns out that there similarities with the "pre-Big Bang"
scenario in String Theory.Comment: 35 pages, 2 figures, added additional discussion of gauge fixing and
self-adjointness of the Hamiltonian, added reference
Resolution of Nearly Mass Degenerate Higgs Bosons and Production of Black Hole Systems of Known Mass at a Muon Collider
The direct s-channel coupling to Higgs bosons is 40000 times greater for
muons than electrons; the coupling goes as mass squared. High precision
scanning of the lighter and the higher mass and is thus
possible with a muon collider. The and are expected to be nearly
mass degenerate and to be CP even and odd, respectively. A muon collider could
resolve the mass degeneracy and make CP measurements. The origin of CP
violation in the and meson systems might lie in the the
Higgs bosons. If large extra dimensions exist, black holes with
lifetimes of seconds could be created and observed via Hawking
radiation at the LHC. Unlike proton or electron colliders, muon colliders can
produce black hole systems of known mass. This opens the possibilities of
measuring quantum remnants, gravitons as missing energy, and scanning
production turn on. Proton colliders are hampered by parton distributions and
CLIC by beamstrahlung. The ILC lacks the energy reach.Comment: Latex, 5 pages, 2 figures, proceedings to the DPF 2004: Annual
Meeting of the Division of Particles and Fields of APS, 26 August-31 August
2004, Riverside, CA, US
Nonmetricity and torsion induced by dilaton gravity in two dimension
We develop a theory in which there are couplings amongst Dirac spinor,
dilaton and non-Riemannian gravity and explore the nature of connection-induced
dilaton couplings to gravity and Dirac spinor when the theory is reformulated
in terms of the Levi-Civita connection. After presenting some exact solutions
without spinors, we investigate the minimal spinor couplings to the model and
in conclusion we can not find any nontrivial dilaton couplings to spinor.Comment: Added references, Accepted for publication in GR
Collider Production of TeV Scale Black Holes and Higher-Curvature Gravity
We examine how the production of TeV scale black holes at colliders is
influenced by the presence of Lovelock higher-curvature terms in the action of
models with large extra dimensions. Such terms are expected to arise on rather
general grounds, e.g., from string theory and are often used in the literature
to model modifications to the Einstein-Hilbert action arising from quantum
and/or stringy corrections. While adding the invariant which is quadratic in
the curvature leads to quantitative modifications in black hole properties,
cubic and higher invariants are found to produce significant qualitative
changes, e.g., classically stable black holes. We use these higher-order
curvature terms to construct a toy model of the black hole production cross
section threshold. For reasonable parameter values we demonstrate that detailed
measurements of the properties of black holes at future colliders will be
highly sensitive to the presence of the Lovelock higher-order curvature terms.Comment: 37 pages, 11 figures, references adde
Competing PT potentials and re-entrant PT symmetric phase for a particle in a box
We investigate the effects of competition between two complex,
-symmetric potentials on the -symmetric phase of a
"particle in a box". These potentials, given by and
, represent long-range and localized
gain/loss regions respectively. We obtain the -symmetric phase in
the plane, and find that for locations near the edge of the
box, the -symmetric phase is strengthened by additional losses to
the loss region. We also predict that a broken -symmetry will be
restored by increasing the strength of the localized potential. By
comparing the results for this problem and its lattice counterpart, we show
that a robust -symmetric phase in the continuum is consistent
with the fragile phase on the lattice. Our results demonstrate that systems
with multiple, -symmetric potentials show unique, unexpected
properties.Comment: 7 pages, 3 figure
TeV-Scale Black Hole Lifetimes in Extra-Dimensional Lovelock Gravity
We examine the mass loss rates and lifetimes of TeV-scale extra dimensional
black holes (BH) in ADD-like models with Lovelock higher-curvature terms
present in the action. In particular we focus on the predicted differences
between the canonical and microcanonical ensemble statistical mechanics
descriptions of the Hawking radiation that results in the decay of these BH. In
even numbers of extra dimensions the employment of the microcanonical approach
is shown to generally lead to a significant increase in the BH lifetime as in
case of the Einstein-Hilbert action. For odd numbers of extra dimensions,
stable BH remnants occur when employing either description provided the highest
order allowed Lovelock invariant is present. However, in this case, the time
dependence of the mass loss rates obtained employing the two approaches will be
different. These effects are in principle measurable at future colliders.Comment: 27 pages, 9 figs; Refs. and discussion adde
Quasinormal mode characterization of evaporating mini black holes
According to recent theoretical developments, it might be possible to produce
mini black holes in the high energy experiments in the LHC at CERN. We propose
here a model based on the -dimensional Vaidya metric in double null
coordinates for these decaying black holes. The associated quasinormal modes
are considered. It is shown that only in the very last instants of the
evaporation process the stationary regime for the quasinormal modes is broken,
implying specific power spectra for the perturbations around these mini
black-holes. From scattered fields one could recover, in principle, the black
hole parameters as well as the number of extra dimensions. The still mysterious
final fate of such objects should not alter significantly our main conclusions.Comment: v4: 9 pages, 3 figures. Minor correction
Entropic corrections to Newton's law
In this short letter we calculate separately the generalized uncertainty
principle (GUP) and self gravitational corrections to the Newton's
gravitational formula. We show that for a complete description of the GUP and
self-gravity effects, both temperature and the entropy must be modified.Comment: 4 pages, Accepted for publication in "Physica Scripta",Title changed,
Major revisio
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