591 research outputs found
Radiatively Induced Neutrino Masses and Large Higgs-Neutrino Couplings in the Standard Model with Majorana Fields
The Higgs sector of the Standard Model with one right-handed neutrino per
family is systematically analyzed. In a model with intergenerational
independent mixings between families, we can account for very light neutrinos
acquiring Majorana masses radiatively at the first electroweak loop level. We
also find that in such a scenario the Higgs coupling to the light-heavy
neutrinos and to the heavy-heavy ones may be remarkably enhanced with
significant implications for the production of these heavy neutrinos at high
energy colliders.Comment: Making the text of an old paper electronically availabl
Conformally coupled dark matter
Dark matter is obtained from a scalar field coupled conformally to
gravitation; the scalar being a relict of Dirac's gauge function. This
conformally coupled dark matter includes a gas of very light () neutral bosons having spin 0, as well as a
time-dependent global scalar field, both pervading all of the cosmic space. The
time-development of this dark matter in the expanding F-R-W universe is
investigated, and an acceptable cosmological behaviour is obtained.Comment: LaTEX File 10 pages, no figure
Analysing the elasticity difference tensor of general relativity
The elasticity difference tensor, used in [1] to describe elasticity
properties of a continuous medium filling a space-time, is here analysed from
the point of view of the space-time connection. Principal directions associated
with this tensor are compared with eigendirections of the material metric.
Examples concerning spherically symmetric and axially symmetric space-times are
then presented.Comment: 17 page
Coulomb Gauge QCD, Confinement, and the Constituent Representation
Quark confinement and the genesis of the constituent quark model are examined
in nonperturbative QCD in Coulomb gauge. We employ a self-consistent method to
construct a quasiparticle basis and to determine the quasiparticle interaction.
The results agree remarkably well with lattice computations. They also
illustrate the mechanism by which confinement and constituent quarks emerge,
provide support for the Gribov-Zwanziger confinement scenario, clarify several
perplexing issues in the constituent quark model, and permit the construction
of an improved model of low energy QCD.Comment: 43 pages, 14 figures, revtex, uses psfig.st
Volume element structure and roton-maxon-phonon excitations in superfluid helium beyond the Gross-Pitaevskii approximation
We propose a theory which deals with the structure and interactions of volume
elements in liquid helium II. The approach consists of two nested models linked
via parametric space. The short-wavelength part describes the interior
structure of the fluid element using a non-perturbative approach based on the
logarithmic wave equation; it suggests the Gaussian-like behaviour of the
element's interior density and interparticle interaction potential. The
long-wavelength part is the quantum many-body theory of such elements which
deals with their dynamics and interactions. Our approach leads to a unified
description of the phonon, maxon and roton excitations, and has noteworthy
agreement with experiment: with one essential parameter to fit we reproduce at
high accuracy not only the roton minimum but also the neighboring local maximum
as well as the sound velocity and structure factor.Comment: 9 pages, 6 figure
Complement Split Product C5a Mediates the LipopolysaccharideâInduced Mobilization of CfuâS and Haemopoietic Progenitor Cells, But Not the Mobilization Induced By Proteolytic Enzymes
Abstract. Intravenous (i.v.) injection of mice with lipopolysaccharide (LPS), and the proteolytic enzymes trypsin and proteinase, mobilizes pluripotent haemopoietic stem cells (CFUâs) as well as granulocyteâmacrophage progenitor cells (GMâCFU) and the early progenitors of the erythroid lineage (EâBFU) from the haemopoietic tissues into the peripheral blood. We investigated the involvement of the complement (C) system in this process. It appeared that the early mobilization induced by LPS and other activators of the alternative complement pathway, such as Listeria monocytogenes (Lm) and zymosan, but not that induced by the proteolytic enzymes, was absent in C5âdeficient mice. the mobilization by C activators in these mice could be restored by injection of C5âsufficient serum, suggesting a critical role for C5. The manner in which C5 was involved in the C activationâmediated stem cell mobilization was studied using a serum transfer system. C5âsufficient serum, activated in vitro by incubation with Lm and subsequently liberated from the bacteria, caused mobilization in both C5âsufficient and C5âdeficient mice. C5âdeficient serum was not able to do so. the resistance of the mobilizing principle to heat treatment (56°C, 30 min) strongly suggests that it is identical with the C5 split product C5a, or an in vivo derivative of C5a. This conclusion was reinforced by the observation that a single injection of purified rat C5a into C5âdeficient mice also induced mobilization of CFUâs. Copyrigh
Lepton Flavor Violating Process in Bi-maximal texture of Neutrino Mixings
We investigate the lepton flavor violation in the framework of the MSSM with
right-handed neutrinos taking the large mixing angle MSW solution in the
quasi-degenerate and the inverse-hierarchical neutrino masses. We predict the
branching ratio of and processes
assuming the degenerate right-handed Majorana neutrino masses. We find that the
branching ratio in the quasi-degenerate neutrino mass spectrum is 100 times
smaller than the ones in the inverse-hierarchical and the hierarchical neutrino
spectra. We emphasize that the magnitude of is one of important
ingredients to predict BR(). The effect of the deviation
from the complete-degenerate right-handed Majorana neutrino masses are also
estimated. Furtheremore, we examine the S_{3\sL}\times S_{3\sR} model, which
gives the quasi-degenerate neutrino masses, and the Shafi-Tavartkiladze model,
which gives the inverse-hierarchical neutrino masses. Both predicted branching
ratios of are smaller than the experimantal bound.Comment: Latex file, 38 pages, 10 figures, revised versio
Energy and Momentum Densities Associated with Solutions Exhibiting Directional Type Singularities
We obtain the energy and momentum densities of a general static axially
symmetric vacuum space-time described by the Weyl metric, using Landau-Lifshitz
and Bergmann-Thomson energy-momentum complexes. These two definitions of the
energy-momentum complex do not provide the same energy density for the
space-time under consideration, while give the same momentum density. We show
that, in the case of Curzon metric which is a particular case of the Weyl
metric, these two definitions give the same energy only when .
Furthermore, we compare these results with those obtained using Einstein,
Papapetrou and M{\o}ller energy momentum complexes.Comment: 10 pages, references added, minor corrections [Admin note:
substantial overlap with gr-qc/0403097 , gr-qc/0403039
Nuclear Skins and Halos in the Mean-Field Theory
Nuclei with large neutron-to-proton ratios have neutron skins, which manifest
themselves in an excess of neutrons at distances greater than the radius of the
proton distribution. In addition, some drip-line nuclei develop very extended
halo structures. The neutron halo is a threshold effect; it appears when the
valence neutrons occupy weakly bound orbits. In this study, nuclear skins and
halos are analyzed within the self-consistent Skyrme-Hartree-Fock-Bogoliubov
and relativistic Hartree-Bogoliubov theories for spherical shapes. It is
demonstrated that skins, halos, and surface thickness can be analyzed in a
model-independent way in terms of nucleonic density form factors. Such an
analysis allows for defining a quantitative measure of the halo size. The
systematic behavior of skins, halos, and surface thickness in even-even nuclei
is discussed.Comment: 22 RevTeX pages, 22 EPS figures included, submitted to Physical
Review
Exact Hypersurface-Homogeneous Solutions in Cosmology and Astrophysics
A framework is introduced which explains the existence and similarities of
most exact solutions of the Einstein equations with a wide range of sources for
the class of hypersurface-homogeneous spacetimes which admit a Hamiltonian
formulation. This class includes the spatially homogeneous cosmological models
and the astrophysically interesting static spherically symmetric models as well
as the stationary cylindrically symmetric models. The framework involves
methods for finding and exploiting hidden symmetries and invariant submanifolds
of the Hamiltonian formulation of the field equations. It unifies, simplifies
and extends most known work on hypersurface-homogeneous exact solutions. It is
shown that the same framework is also relevant to gravitational theories with a
similar structure, like Brans-Dicke or higher-dimensional theories.Comment: 41 pages, REVTEX/LaTeX 2.09 file (don't use LaTeX2e !!!) Accepted for
publication in Phys. Rev.
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