6,155 research outputs found
Quark matter equation of state and stellar properties
In this paper we study strange matter by investigating the stability window
within the QMDD model at zero temperature and check that it can explain the
very massive pulsar recently detected. We compare our results with the ones
obtained from the MIT bag model and see that the QMDD model can explain larger
masses, due to the stiffening of the equation of state
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
Twinlike Models for Self-Dual Maxwell-Higgs Theories
In this work we present a theoretical framework that allows for the existence
of coherent twinlike models in the context of self-dual Maxwell-Higgs theories.
We verify the consistence of this framework by using it to develop some
twinlike self-dual Maxwell-Higgs models. We use a combination of theoretical
and numerical techniques to show that these models exhibit the very same
topological BPS structures, including their field configurations and total
energy. The study shows that it is possible to develop a completely consistent
prescription, which extends the idea of twinlike models to the case of vortices
in Maxwell-Higgs theories.Comment: 7 pages, 3 figures; version to appear in PR
New results on twinlike models
In this work we study the presence of kinks in models described by a single
real scalar field in bidimensional spacetime. We work within the first-order
framework, and we show how to write first-order differential equations that
solve the equations of motion. The first-order equations strongly simplify the
study of linear stability, which is implemented on general grounds. They also
lead to a direct investigation of twinlike theories, which is used to introduce
a family of models that support the same defect structure, with the very same
energy density and linear stability.Comment: 6 pages, 1 figur
Stability windows for proto-quark stars
We investigate the existence of possible stable strange matter and related
stability windows at finite temperature for different models that are generally
applied to describe quark stars, namely, the quark-mass density dependent
model, the MIT bag model and the Nambu-Jona-Lasinio model. We emphasize that,
although the limits for stable strange matter depend on a comparison with the
ground state of 56Fe, which is a zero temperature state, the quantity that has
to be used in the search for strange matter in proto-quark stars is the free
energy and we analyze stability windows up to temperatures of the order of 40
MeV. The effects of strong magnetic fields on stability windows are computed
and the resulting mass-radius relations for different stages of the proto-quark
star are analyzed.Comment: Published versio
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