10,779 research outputs found
Space-time Uncertainty Principle from Breakdown of Topological Symmetry
Starting from topological quantum field theory, we derive space-time
uncertainty relation with respect to the time interval and the spatial length
proposed by Yoneya through breakdown of topological symmetry in the large N
matrix model. This work suggests that the topological symmetry might be an
underlying higher symmetry behind the space-time uncertainty principle of
string theory.Comment: 6 pages, Late
Locally Localized Gravity Models in Higher Dimensions
We explore the possibility of generalizing the locally localized gravity
model in five space-time dimensions to arbitrary higher dimensions. In a
space-time with negative cosmological constant, there are essentially two kinds
of higher-dimensional cousins which not only take an analytic form but also are
free from the naked curvature singularity in a whole bulk space-time. One
cousin is a trivial extension of five-dimensional model, while the other one is
in essence in higher dimensions. One interesting observation is that in the
latter model, only anti-de Sitter () brane is physically meaningful
whereas de Sitter () and Minkowski () branes are dismissed.
Moreover, for brane in the latter model, we study the property of
localization of various bulk fields on a single brane. In particular, it is
shown that the presence of the brane cosmological constant enables bulk gauge
field and massless fermions to confine to the brane only by a gravitational
interaction. We find a novel relation between mass of brane gauge field and the
brane cosmological constant.Comment: 20 pages, LaTex 2e, revised version (to appear in Phys. Rev. D
Variation of Electrostatic Coupling and Investigation of Current Percolation Paths in Nanocrystalline Silicon Cross Transistors
Nanocrystalline silicon thin films are promising materials for the development of advanced Large Scale Integration compatible quantum-dot and single-electron charging devices. The films consist of nanometer-scale grains of crystalline silicon, separated by amorphous silicon or silicon dioxide grain boundaries up to a few nanometer thick. These films have been used to fabricate single-electron transistor and memory devices, where the grains form single-electron charging islands isolated by tunnel barriers formed by the grain boundaries. The grain boundary tunnel barrier isolating the grains is also of great importance, as this determines the extent of the electrostatic and tunnel coupling between different grains. These effects can lead to the nanocrystalline silicon thin film behaving as a system of coupled quantum dots.& more..
Cold dark matter and primordial superheavy particles
The hypothesis that cold dark matter consists of primordial superheavy
particles, the decay of short lifetime component of which led to the observable
mass of matter while long living component survived up to modern times
manifesting its presence in high energetic cosmic rays particles is
investigated.Comment: LaTeX, 5 pages, no figure
Unusual interplay between copper-spin and vortex dynamics in slightly overdoped La{1.83}Sr{0.17}CuO{4}
Our inelastic neutron scattering experiments of the spin excitations in the
slightly overdoped La{1.83}Sr{0.17}CuO{4} compound show that, under the
application of a magnetic field of 5 Tesla, the low-temperature susceptibility
undergoes a weight redistribution centered at the spin-gap energy. Furthermore,
by comparing the temperature dependence of the neutron data with
ac-susceptibility and magnetization measurements, we conclude that the filling
in of the spin gap tracks the irreversibility/melting temperature rather than
Tc2, which indicates an unusual interplay between the magnetic vortices and the
spin excitations even in the slightly overdoped regime of high-temperature
superconductors.Comment: 7 pages, including 5 figure
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