8,633 research outputs found
Randall-Sundrum Zero Mode as a Penrose Limit
A generalization of the limiting procedure of Penrose, which allows non-zero
cosmological constants and takes into account metrics that contain homogeneous
functions of degree zero, is presented. It is shown that any spacetime which
admits a spacelike conformal Killing vector has a limit which is conformal to
plane waves. If the spacetime is an Einstein space, its limit exists only if
the cosmological constant is negative or zero. When the conformal Killing
vector is hypersurface orthogonal, the limits of Einstein spacetimes are
certain AdS plane waves. In this case the nonlinear version of the
Randall-Sundrum zero mode is obtained as the limit of the brane world
scenarios.Comment: 8 pages,LaTe
Local current distribution at large quantum dots (QDs): a self-consistent screening model
We report the implementation of the self-consistent Thomas-Fermi screening
theory, together with the local Ohm's law to a quantum dot system in order to
obtain local current distribution within the dot and at the leads. We consider
a large dot (size
nm) defined by split gates, and coupled to the leads. Numerical
calculations show that the non-dissipative current is confined to the
incompressible strips. Due to the non-linear screening properties of the 2DES
at low temperatures, this distribution is highly sensitive to external magnetic
field. Our findings support the phenomenological models provided by the
experimental studies so far, where the formation of the (direct) edge channels
dominate the transport.Comment: 6 Pages, 2 Figure
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