9,031 research outputs found
Monojet and Single Photon Signals from Universal Extra Dimensions
The usual universal extra dimensions scenario does not allow for single
production of first level Kaluza-Klein (KK) excitations of matter due to the KK
number conservation. However, if the matter fields are localized on a fat brane
embedded in a higher dimensional space, matter-gravitation interactions violate
KK number, and the production of single KK excitations becomes possible. In
this paper we analyze the production of a single KK matter excitation together
with a graviton in the final state, and study the potential for discovery at
the Tevatron and Large Hadron Collider.Comment: 15 pages, 5 figure
Stability of Circular Orbits in General Relativity: A Phase Space Analysis
Phase space method provides a novel way for deducing qualitative features of
nonlinear differential equations without actually solving them. The method is
applied here for analyzing stability of circular orbits of test particles in
various physically interesting environments. The approach is shown to work in a
revealing way in Schwarzschild spacetime. All relevant conclusions about
circular orbits in the Schwarzschild-de Sitter spacetime are shown to be
remarkably encoded in a single parameter. The analysis in the rotating Kerr
black hole readily exposes information as to how stability depends on the ratio
of source rotation to particle angular momentum. As a wider application, it is
exemplified how the analysis reveals useful information when applied to motion
in a refractive medium, for instance, that of optical black holes.Comment: 20 pages. Accepted for publication in Int. J. theor. Phy
Dual-layer network representation exploiting information characterization
In this paper, a logical dual-layer representation approach is proposed to facilitate the analysis of directed and weighted complex networks. Unlike the single logical layer structure, which was widely used for the directed and weighted flow graph, the proposed approach replaces the single layer with a dual-layer structure, which introduces a provider layer and a requester layer. The new structure provides the characterization of the nodes by the information, which they provide to and they request from the network. Its features are explained and its implementation and visualization are also detailed. We also design two clustering methods with different strategies respectively, which provide the analysis from different points of view. The effectiveness of the proposed approach is demonstrated using a simplified example. By comparing the graph layout with the conventional directed graph, the new dual-layer representation reveals deeper insight into the complex networks and provides more opportunities for versatile clustering analysis.The National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Grant Reference Number RP-PG-0310-1004)
Revisiting perfect fluid dark matter: Observational constraints from our galaxy
We revisit certain features of an assumed spherically symmetric perfect fluid
dark matter halo in the light of the observed data of our galax
A Model for Neutrino and Charged Lepton Masses in Extra Dimensions
We propose a model with one large submm size extra dimension in which the
gravity and right-handed (RH) neutrino propagate, but the three Standard Model
(SM) families are confined to fat branes of TeV^(-1) size or smaller. The
charged leptons and the light neutrinos receive mass from the five dimensional
Yukawa couplings with the SM singlet neutrino via electroweak Higgs, while the
KK excitations of the SM singlet neutrino gets large TeV scale masses from the
five dimensional Yukawa coupling with an electroweak singlet Higgs. The model
gives non-hierarchical light neutrino masses, accommodate hierarchical charged
lepton masses, and naturally explain why the light neutrino masses are so much
smaller compared to the charged lepton masses. Large neutrino mixing is
naturally expected in this scenario. The light neutrinos are Dirac particles in
this model, hence neutrinoless double beta decay is not allowed. The model has
also several interesting collider implications and can be tested at the LHC.Comment: 11 pages, no figure
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