5,454 research outputs found
Dynamical properties of nuclear and stellar matter and the symmetry energy
The effects of density dependence of the symmetry energy on the collective
modes and dynamical instabilities of cold and warm nuclear and stellar matter
are studied in the framework of relativistic mean-field hadron models. The
existence of the collective isovector and possibly an isoscalar collective mode
above saturation density is discussed. It is shown that soft equations of state
do not allow for a high density isoscalar collective mode, however, if the
symmetry energy is hard enough an isovector mode will not disappear at high
densities. The crust-core transition density and pressure are obtained as a
function of temperature for -equilibrium matter with and without
neutrino trapping. An estimation of the size of the clusters formed in the
non-homogeneous phase as well as the corresponding growth rates and
distillation effect is made. It is shown that cluster sizes increase with
temperature, that the distillation effect close to the inner edge of the
crust-core transition is very sensitive to the symmetry energy, and that,
within a dynamical instability calculation, the pasta phase exists in warm
compact stars up to 10 - 12 MeV.Comment: 16 pages, 10 figures. Submitted for publication in Phys. Rev.
Non-unitary representations of the SU(2) algebra in the Dirac equation with a Coulomb potential
A novel realization of the classical SU(2) algebra is introduced for the
Dirac relativistic hydrogen atom defining a set of operators that, besides,
allow the factorization of the problem. An extra phase is needed as a new
variable in order to define the algebra. We take advantage of the operators to
solve the Dirac equation using algebraic methods. To acomplish this, a similar
path to the one used in the angular momentum case is employed; hence, the
radial eigenfuntions calculated comprise non unitary representations of the
algebra. One of the interesting properties of such non unitary representations
is that they are not labeled by integer nor by half-integer numbers as happens
in the usual angular momentum representation.Comment: 20 pages 1 eps figure in a single zipped file, submitted to J. Math.
Phy
Effective models of quantum gravity induced by Planck scale modifications in the covariant quantum algebra
In this paper we introduce a modified covariant quantum algebra based in the
so-called Quesne-Tkachuk algebra. By means of a deformation procedure we arrive
at a class of higher derivative models of gravity. The study of the particle
spectra of these models reveals an equivalence with the physical content of the
well-known renormalizable and super-renormalizable higher derivative gravities.
The particle spectrum exhibits the presence of spurious complex ghosts and, in
light of this problem, we suggest an interesting interpretation in the context
of minimal length theories. Also, a discussion regarding the non-relativistic
potential energy is proposed.Comment: Small corrections were made; improved figures; results unchanged;
published versio
Entangling two superconducting LC coherent modes via a superconducting flux qubit
Based on a pure solid-state device consisting of two superconducting LC
circuits coupled to a superconducting flux qubit, we propose in this paper that
the maximally entangled coherent states of the two LC modes can be generated
for arbitrary coherent states through flux qubit controls.Comment: 5 pages, 2 figure
Fatores comuns de risco de mercado, tamanho, valor e diferenciais de juros nos retornos esperados das ações brasileiras
Multi-scalar tachyon potential on non-BPS domain walls
We have considered the multi-scalar and multi-tachyon fields living on a 3d
domain wall embedded in a 5d dimensional Minkowski spacetime. The effective
action for such a domain wall can be found by integrating out the normal modes
as vibrating modes around the domain wall solution of a truncated 5d
supergravity action. The multi-scalar tachyon potential are good enough to
modeling assisted inflation scenario with multi-tachyon fields. The tachyon
condensation are also briefly addressed.Comment: version to appear in JHEP, 18 pages, 3 figure
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