43,891 research outputs found
A rotating cylinder in an asymptotically locally anti-de Sitter background
A family of exact solutions is presented which represents a rigidly rotating
cylinder of dust in a background with a negative cosmological constant. The
interior of the infinite cylinder is described by the Godel solution. An exact
solution for the exterior solution is found which depends both on the rotation
of the interior and on its radius. For values of these parameters less than a
certain limit, the exterior solution is shown to be locally isomorphic to the
Linet-Tian solution. For values larger than another limit, it is shown that the
exterior solution extends into a region which contains closed timelike curves.
At large distances from the source, the space-time is shown to be asymptotic
locally to anti-de Sitter space.Comment: To appear in Classical and Quantum Gravit
Shear-free and homology conditions for self-gravitating dissipative fluids
The shear free condition is studied for dissipative relativistic
self-gravitating fluids in the quasi-static approximation. It is shown that, in
the Newtonian limit, such condition implies the linear homology law for the
velocity of a fluid element, only if homology conditions are further imposed on
the temperature and the emission rate. It is also shown that the shear-free
plus the homogeneous expansion rate conditions are equivalent (in the Newtonian
limit) to the homology conditions. Deviations from homology and their
prospective applications to some astrophysical scenarios are discussed, and a
model is worked out.Comment: 13 pages Latex. To apppear in Month.Not.Roy.Astr.Soc. Corrected typo
Cylindrical Collapse and Gravitational Waves
We study the matching conditions for a collapsing anisotropic cylindrical
perfect fluid, and we show that its radial pressure is non zero on the surface
of the cylinder and proportional to the time dependent part of the field
produced by the collapsing fluid. This result resembles the one that arises for
the radiation - though non-gravitational - in the spherically symmetric
collapsing dissipative fluid, in the diffusion approximation.Comment: Some comments and a new reference added. To appear in Class. Quantum.
Gra
Geodesics in Lewis Spacetime
The geodesic equations are integrated for the Lewis metric and the effects of
the different parameters appearing in the Weyl class on the motion of test
particles are brought out. Particular attention deserves the appearance of a
force parallel to the axial axis and without Newtonian analogue.Comment: 15 pages, Late
Lower Mass Bound on the mass via Neutrinoless Double Beta Decay in a 3-3-1 Model
The discovery of neutrino masses has raised the importance of studies in the
context of neutrinoless double beta decay, which constitutes a landmark for
lepton number violation. The standard interpretation is that the light massive
neutrinos, that we observed oscillating in terrestrial experiments, mediate
double beta decay. In the minimal 3-3-1 model, object of our study, there is an
additional contribution that stems from the mixing between a new charged vector
boson, , and the Standard Model W boson. Even after setting this
mixing to be very small, we show that tight constraints arise from the
non-observation of neutrinoless double beta decay. Indeed, we derive bounds on
the mass of the gauge boson that might exceed those from collider
probes, and most importantly push the scale of symmetry breaking beyond its
validity, leading to the exclusion of the minimal 3-3-1 model.Comment: 16 pages, 5 figure
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