2,616 research outputs found
Degenerate Topological Vortex solutions from a generalized Abelian Higgs Model with a Chern-Simons term
We consider a generalization of the abelian Higgs model with a Chern-Simons
term by modifying two terms of the usual Lagrangian. We multiply a dielectric
function with the Maxwell kinetic energy term and incorporate nonminimal
interaction by considering generalized covariant derivative. We show that for a
particular choice of the dielectric function this model admits topological
vortices satisfying Bogomol'nyi bound for which the magnetic flux is not
quantized even though the energy is quantized. Furthermore, the vortex solution
in each topological sector is infinitely degenerate.Comment: 13 pages (one figure not included), Revtex, IP/BBSR/93-5
Exact Self-dual Soliton Solutions in a Gauged O(3) Sigma Model with Anomalous Magnetic Moment Interaction
It is shown that a gauged nonlinear sigma model with anomalous
magnetic moment interaction in dimensions is exactly integrable for
static, self-dual field configurations. The matter fields are exactly
equivalent to those of the usual ungauged nonlinear sigma model. These
static soliton solutions can be mapped into an Abelian purely magnetic vortex
solutions through a suitable reduction of the non-Abelian gauge group. A
relativistic Abelian model in dimensions is also presented where these
purely magnetic vortices can be realized.Comment: A discussion on case has been made. New references have been
added. To appear in Physics Letters B. RevTeX, 13 pages, no figur
EYM equations in the presence of q-stars
We study Einstein-Yang-Mills equations in the presence of gravitating
non-topological soliton field configurations, of q-ball type. We produce
numerical solutions, stable with respect to gravitational collapse and to
fission into free particles, and we study the effect of the field strength and
the eigen-frequency to the soliton parameters. We also investigate the
formation of such soliton stars when the spacetime is asymptotically anti de
Sitter.Comment: 11 pages, to appear in Phys. Rev.
Q-stars in extra dimensions
We study q-stars with global and local U(1) symmetry in extra dimensions in
asymptotically anti de Sitter or flat spacetime. The behavior of the mass,
radius and particle number of the star is quite different in 3 dimensions, but
in 5, 6, 8 and 11 dimensions is similar to the behavior in 4.Comment: 18 pages, to appear in Phys. Rev.
Bogomol'nyi Equations of Maxwell-Chern-Simons vortices from a generalized Abelian Higgs Model
We consider a generalization of the abelian Higgs model with a Chern-Simons
term by modifying two terms of the usual Lagrangian. We multiply a dielectric
function with the Maxwell kinetic energy term and incorporate nonminimal
interaction by considering generalized covariant derivative. We show that for a
particular choice of the dielectric function this model admits both topological
as well as nontopological charged vortices satisfying Bogomol'nyi bound for
which the magnetic flux, charge and angular momentum are not quantized. However
the energy for the topolgical vortices is quantized and in each sector these
topological vortex solutions are infinitely degenerate. In the nonrelativistic
limit, this model admits static self-dual soliton solutions with nonzero finite
energy configuration. For the whole class of dielectric function for which the
nontopological vortices exists in the relativistic theory, the charge density
satisfies the same Liouville equation in the nonrelativistic limit.Comment: 30 pages(4 figures not included), RevTeX, IP/BBSR/93-6
Ecology of active and passive players and their impact on information selection
Is visitors' attendance a fair indicator of a web site's quality? Internet
sub-domains are usually characterized by power law distributions of visits,
thus suggesting a richer-get-richer process. If this is the case, the number of
visits is not a relevant measure of quality. If, on the other hand, there are
active players, i.e. visitors who can tell the value of the information
available, better sites start getting richer after a crossover time.Comment: Accepted for publication on Phisica
Vortex solutions of a Maxwell-Chern-Simons field coupled to four-fermion theory
We find the static vortex solutions of the model of Maxwell-Chern-Simons
gauge field coupled to a (2+1)-dimensional four-fermion theory. Especially, we
introduce two matter currents coupled to the gauge field minimally: the
electromagnetic current and a topological current associated with the
electromagnetic current. Unlike other Chern-Simons solitons the N-soliton
solution of this theory has binding energy and the stability of the solutions
is maintained by the charge conservation laws.Comment: 7 pages, harvmac, To be published in Phys. Rev. D5
The Importance of DNA Repair in Tumor Suppression
The transition from a normal to cancerous cell requires a number of highly
specific mutations that affect cell cycle regulation, apoptosis,
differentiation, and many other cell functions. One hallmark of cancerous
genomes is genomic instability, with mutation rates far greater than those of
normal cells. In microsatellite instability (MIN tumors), these are often
caused by damage to mismatch repair genes, allowing further mutation of the
genome and tumor progression. These mutation rates may lie near the error
catastrophe found in the quasispecies model of adaptive RNA genomes, suggesting
that further increasing mutation rates will destroy cancerous genomes. However,
recent results have demonstrated that DNA genomes exhibit an error threshold at
mutation rates far lower than their conservative counterparts. Furthermore,
while the maximum viable mutation rate in conservative systems increases
indefinitely with increasing master sequence fitness, the semiconservative
threshold plateaus at a relatively low value. This implies a paradox, wherein
inaccessible mutation rates are found in viable tumor cells. In this paper, we
address this paradox, demonstrating an isomorphism between the conservatively
replicating (RNA) quasispecies model and the semiconservative (DNA) model with
post-methylation DNA repair mechanisms impaired. Thus, as DNA repair becomes
inactivated, the maximum viable mutation rate increases smoothly to that of a
conservatively replicating system on a transformed landscape, with an upper
bound that is dependent on replication rates. We postulate that inactivation of
post-methylation repair mechanisms are fundamental to the progression of a
tumor cell and hence these mechanisms act as a method for prevention and
destruction of cancerous genomes.Comment: 7 pages, 5 figures; Approximation replaced with exact calculation;
Minor error corrected; Minor changes to model syste
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