467 research outputs found
Quantum phase shift and neutrino oscillations in a stationary, weak gravitational field
A new method based on Synge's world function is developed for determining
within the WKB approximation the gravitationally induced quantum phase shift of
a particle propagating in a stationary spacetime. This method avoids any
calculation of geodesics. A detailed treatment is given for relativistic
particles within the weak field, linear approximation of any metric theory. The
method is applied to the calculation of the oscillation terms governing the
interference of neutrinos considered as a superposition of two eigenstates
having different masses. It is shown that the neutrino oscillations are not
sensitive to the gravitomagnetic components of the metric as long as the spin
contributions can be ignored. Explicit calculations are performed when the
source of the field is a spherical, homogeneous body. A comparison is made with
previous results obtained in Schwarzschild spacetime.Comment: 14 pages, no figure. Enlarged version; added references. In the
Schwarzschild case, our results on the non-radial propagation are compared
with the previous work
Dynamics of a self-gravitating thin cosmic string
We assume that a self-gravitating thin string can be locally described by
what we shall call a smoothed cone. If we impose a specific constraint on the
model of the string, then its central line obeys the Nambu-Goto equations. If
no constraint is added, then the worldsheet of the central line is a totally
geodesic surface.Comment: 20 pages, latex, 1 figure, final versio
Ultimate decoherence border for matter-wave interferometry
Stochastic backgrounds of gravitational waves are intrinsic fluctuations of
spacetime which lead to an unavoidable decoherence mechanism. This mechanism
manifests itself as a degradation of the contrast of quantum interferences. It
defines an ultimate decoherence border for matter-wave interferometry using
larger and larger molecules. We give a quantitative characterization of this
border in terms of figures involving the gravitational environment as well as
the sensitivity of the interferometer to gravitational waves. The known level
of gravitational noise determines the maximal size of the molecular probe for
which interferences may remain observable. We discuss the relevance of this
result in the context of ongoing progresses towards more and more sensitive
matter-wave interferometry.Comment: 4 page
Leukemia-related chromosomal loss detected in hematopoietic progenitor cells of benzene-exposed workers.
Benzene exposure causes acute myeloid leukemia and hematotoxicity, shown as suppression of mature blood and myeloid progenitor cell numbers. As the leukemia-related aneuploidies monosomy 7 and trisomy 8 previously had been detected in the mature peripheral blood cells of exposed workers, we hypothesized that benzene could cause leukemia through the induction of these aneuploidies in hematopoietic stem and progenitor cells. We measured loss and gain of chromosomes 7 and 8 by fluorescence in situ hybridization in interphase colony-forming unit-granulocyte-macrophage (CFU-GM) cells cultured from otherwise healthy benzene-exposed (n=28) and unexposed (n=14) workers. CFU-GM monosomy 7 and 8 levels (but not trisomy) were significantly increased in subjects exposed to benzene overall, compared with levels in the control subjects (P=0.0055 and P=0.0034, respectively). Levels of monosomy 7 and 8 were significantly increased in subjects exposed to <10 p.p.m. (20%, P=0.0419 and 28%, P=0.0056, respectively) and ≥ 10 p.p.m. (48%, P=0.0045 and 32%, 0.0354) benzene, compared with controls, and significant exposure-response trends were detected (P(trend)=0.0033 and 0.0057). These data show that monosomies 7 and 8 are produced in a dose-dependent manner in the blood progenitor cells of workers exposed to benzene, and may be mechanistically relevant biomarkers of early effect for benzene and other leukemogens
Self-force of a point charge in the space-time of a massive wormhole
We consider the self-potential and the self-force for an electrically charged
particle at rest in the massive wormhole space-time. We develop general
approach for the renormalization of electromagnetic field of such particle in
the static space-times and apply it to the space-time of the wormhole with
parameter of the mass, . The self-force is found in manifest form; it is an
attractive force. We discus the peculiarities due to massive parameter of the
wormhole.Comment: 10 pages, 1 figure text correcte
Classical self-forces in a space with a dispiration
We derive the gravitational and electrostatic self-energies of a particle at
rest in the background of a cosmic dispiration (topological defect), finding
that the particle may experience potential steps, well potentials or potential
barriers depending on the nature of the interaction and also on certain
properties of the defect. The results may turn out to be useful in cosmology
and condensed matter physics.Comment: 5 pages, 4 figures, revtex4 fil
Developed Adomian method for quadratic Kaluza-Klein relativity
We develop and modify the Adomian decomposition method (ADecM) to work for a
new type of nonlinear matrix differential equations (MDE's) which arise in
general relativity (GR) and possibly in other applications. The approach
consists in modifying both the ADecM linear operator with highest order
derivative and ADecM polynomials. We specialize in the case of a 44
nonlinear MDE along with a scalar one describing stationary cylindrically
symmetric metrics in quadratic 5-dimensional GR, derive some of their
properties using ADecM and construct the \textit{most general unique power
series solutions}. However, because of the constraint imposed on the MDE by the
scalar one, the series solutions terminate in closed forms exhausting all
possible solutions.Comment: 17 pages (minor changes in reference [30]
Kaluza-Klein and Gauss-Bonnet cosmic strings
We make a systematic investigation of stationary cylindrically symmetric
solutions to the five-dimensional Einstein and Einstein-Gauss-Bonnet equations.
Apart from the five-dimensional neutral cosmic string metric, we find two new
exact solutions which qualify as cosmic strings, one corresponding to an
electrically charged cosmic string, the other to an extended superconducting
cosmic string surrounding a charged core. In both cases, test particles are
deflected away from the singular line source. We extend both kinds of solutions
to exact multi-cosmic string solutions.Comment: 26 pages, LaTex, no figure
Bekenstein Bound, Holography and Brane Cosmology in Charged Black Hole Backgrounds
We obtain a Bekenstein entropy bound for the charged objects in arbitrary
dimensions () using the D-bound recently proposed by Bousso. With the
help of thermodynamics of CFTs corresponding to AdS Reissner-Norstr\"om (RN)
black holes, we discuss the relation between the Bekenstein and
Bekenstein-Verlinde bounds. In particular we propose a Bekenstein-Verlinde-like
bound for the charged systems. In the Einstein-Maxwell theory with a negative
cosmological constant, we discuss the brane cosmology with positive tension
using the Binetruy-Deffayet-Langlois approach. The resulting
Friedman-Robertson-Walker equation can be identified with the one obtained by
the moving domain wall approach in the AdS RN black hole background. Finally we
also address the holographic property of the brane universe.Comment: Latex, 17 pages, v2: minor changes, a reference adde
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