12,793 research outputs found
Generalized Born-Infeld-like models for kinks and branes
In this work we deal with a non-canonical scalar field in the two-dimensional
spacetime. We search for a generalized model that is twin of the standard
model, supporting the same defect structure with the same energy density. We
also study the stability of the defect solution under small fluctuations, which
is governed by a Sturm-Liouville equation, and show how to make it stable. The
model is then modified and used in the five-dimensional spacetime to construct
a thick brane that engenders the first order framework and preserves the
twinlike behavior, under tensorial fluctuations of the metric in its
gravitational sector.Comment: 6 pages; v3, to appear in EP
Exact solutions, energy and charge of stable Q-balls
In this work we deal with nontopological solutions of the Q-ball type in two
spacetime dimensions. We study models of current interest, described by a
Higgs-like and other, similar potentials which unveil the presence of exact
solutions. We use the analytic results to investigate how to control the energy
and charge to make the Q-balls stable.Comment: 11 pages, 18 figures; v2, title changed, reference adde
Stable finite energy global vortices and asymptotic freedom
This work deals with global vortices in the three-dimensional spacetime. We
study the case of a simple model with symmetry and find a way to
describe stable, finite energy global vortices. The price we pay to stabilize
the solution is the presence of scale invariance, but we have found a way to
trade it with an electric charge in a medium with generalized permittivity,
which is further used to capture the basic feature of asymptotic freedom.Comment: 6 pages, 3 figures. To appear in EP
Abrasion of flat rotating shapes
We report on the erosion of flat linoleum "pebbles" under steady rotation in
a slurry of abrasive grit. To quantify shape as a function of time, we develop
a general method in which the pebble is photographed from multiple angles with
respect to the grid of pixels in a digital camera. This reduces digitization
noise, and allows the local curvature of the contour to be computed with a
controllable degree of uncertainty. Several shape descriptors are then employed
to follow the evolution of different initial shapes toward a circle, where
abrasion halts. The results are in good quantitative agreement with a simple
model, where we propose that points along the contour move radially inward in
proportion to the product of the radius and the derivative of radius with
respect to angle
Securitization and Lending Standards: Evidence from the Wholesale Loan Market
securitization;bank risk taking;syndicated loans;financial crisis
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