550 research outputs found
Dynamic Dilatonic Domain Walls
Motivated by the ``universe as a brane'' idea, we investigate the motion of a
-brane (or domain wall) that couples to bulk matter. Usually one would
expect the spacetime outside such a wall to be time dependent however we show
that in certain cases it can be static, with consistency of the Israel
equations yielding relationships between the bulk metric and matter that can be
used as ans\"atze to solve the Einstein equations. As a concrete model we study
a domain wall coupled to a bulk dilaton with Liouville potentials for the
dilaton both in the bulk and on the wall. The bulk solutions we find are all
singular but some have black hole or cosmological horizons, beyond which our
solutions describe domain walls moving in time dependent bulks. A significant
period of world volume inflation occurs if the potential on the wall is not too
steep; in some cases the bulk also inflates (with the wall comoving) while in
others the wall moves relative to a non-inflating bulk. We apply our method to
obtain cosmological solutions of Ho\v{r}ava-Witten theory compactified on a
Calabi-Yau space. tive to a non-inflating bulk. We apply our method to obtain
cosmological solutions of Ho\v{r}ava-Witten theory compactified on a Calabi-Yau
space.Comment: 32 pages LaTeX, 5 .eps figures, corrected some typo
DFR Perturbative Quantum Field theory on Quantum Space Time, and Wick Reduction
We discuss the perturbative approach a` la Dyson to a quantum field theory
with nonlocal self-interaction :phi*...*phi:, according to Doplicher,
Fredenhagen and Roberts (DFR). In particular, we show that the Wick reduction
of non locally time--ordered products of Wick monomials can be performed as
usual, and we discuss a very simple Dyson diagram.Comment: 15 pages, pdf has active hyperlinks. To appear in the proceedings of
the conference on "Rigorous quantum Field Theory", held at Saclay on July
19-21, 2004, on the occasion of Jacques Bros' 70th birthda
Constraint on the heavy sterile neutrino mixing angles in the SO(10) model with double see-saw mechanism
Constraints on the heavy sterile neutrino mixing angles are studied in the
framework of a minimal supersymmetric model with {\it double
see-saw mechanism}. A new singlet matter in addition to the right-handed
neutrinos is introduced to realize the double see-saw mechanism. The minimal
model gives an unambiguous Dirac neutrino mass matrix, which
enables us to predict the masses and the mixing angles in the enlarged neutrino mass matrix. Mixing angles between the light Majorana
neutrinos and the heavy sterile neutrinos are shown to be within the LEP
experimental bound on all ranges of the Majorana phases.Comment: 16 pages, 4 figures; the version to be published in Eur. Phys. J.
Coronal Shock Waves, EUV waves, and their Relation to CMEs. II. Modeling MHD Shock Wave Propagation Along the Solar Surface, Using Nonlinear Geometrical Acoustics
We model the propagation of a coronal shock wave, using nonlinear geometrical
acoustics. The method is based on the Wentzel-Kramers-Brillouin (WKB) approach
and takes into account the main properties of nonlinear waves: i) dependence of
the wave front velocity on the wave amplitude, ii) nonlinear dissipation of the
wave energy, and iii) progressive increase in the duration of solitary shock
waves. We address the method in detail and present results of the modeling of
the propagation of shock-associated extreme-ultraviolet (EUV) waves as well as
Moreton waves along the solar surface in the simplest solar corona model. The
calculations reveal deceleration and lengthening of the waves. In contrast,
waves considered in the linear approximation keep their length unchanged and
slightly accelerate.Comment: 15 pages, 7 figures, accepted for publication in Solar Physic
TeV-scale seesaw from a multi-Higgs model
We suggest new simple model of generating tiny neutrino masses through a
TeV-scale seesaw mechanism without requiring tiny Yukawa couplings. This model
is a simple extension of the standard model by introducing extra one Higgs
singlet, and one Higgs doublet with a tiny vacuum expectation value.
Experimental constraints, electroweak precision data and no large flavor
changing neutral currents, are satisfied since the extra doublet only has a
Yukawa interaction with lepton doublets and right-handed neutrinos, and their
masses are heavy of order a TeV-scale. Since active light neutrinos are
Majorana particles, this model predicts a neutrinoless double beta decay.Comment: 21 pages, 8 figure
Neutrino oscillation parameters from MINOS, ICARUS and OPERA combined
We perform a detailed analysis of the capabilities of the MINOS, ICARUS and
OPERA experiments to measure neutrino oscillation parameters at the atmospheric
scale with their data taken separately and in combination. MINOS will determine
and to within 10% at the 99% C.L. with
10 kton-years of data. While no one experiment will determine with much precision, if its value lies in the combined
sensitivity region of the three experiments, it will be possible to place a
lower bound of O(0.01) at the 95% C.L. on this parameter by combining the data
from the three experiments. The same bound can be placed with a combination of
MINOS and ICARUS data alone.Comment: Version to appear in PR
Proton Decay in a Minimal SUSY SO(10) Model for Neutrino Mixings
A minimal renormalizable SUSY SO(10) model with B-L symmetry broken by {\bf
126} Higgs field has recently been shown to predict all neutrino mixings and
the ratio in agreement with observations.
Unlike models where B-L is broken by {\bf 16} Higgs, this model guarantees
automatic R-parity conservation and hence a stable dark matter as well as the
absence of dim=4 baryon violating operator without any additional symmetry
assumptions. In this paper, we discuss the predictions of the model for proton
decay induced at the GUT scale. We scan over the parameter space of the model
allowed by neutrino data and find upper bounds on the partial lifetime for the
modes yrs and yrs for the
average squark mass of a TeV and wino mass of 200 GeV, when the parameters
satisfy the present lower limits on mode. These
results can be used to test the model.Comment: 17 pages, 6 figures; Minor corrections with improved predictions;
references update
Measuring the Spectra of High Energy Neutrinos with a Kilometer-Scale Neutrino Telescope
We investigate the potential of a future kilometer-scale neutrino telescope
such as the proposed IceCube detector in the South Pole, to measure and
disentangle the yet unknown components of the cosmic neutrino flux, the prompt
atmospheric neutrinos coming from the decay of charmed particles and the
extra-galactic neutrinos, in the 10 TeV to 1 EeV energy range.
Assuming a power law type spectra,
, we quantify the discriminating
power of the IceCube detector and discuss how well we can determine magnitude
() as well as slope () of these two components of the high
energy neutrino spectrum, taking into account the background coming from the
conventional atmospheric neutrinos.Comment: 21 pages, 7 figure
A renormalizable SO(10) GUT scenario with spontaneous CP violation
We consider fermion masses and mixings in a renormalizable SUSY SO(10) GUT
with Yukawa couplings of scalar fields in the representation 10 + 120 + 126
bar. We investigate a scenario defined by the following assumptions: i) A
single large scale in the theory, the GUT scale. ii) Small neutrino masses
generated by the type I seesaw mechanism with negligible type II contributions.
iii) A suitable form of spontaneous CP breaking which induces hermitian mass
matrices for all fermion mass terms of the Dirac type. Our assumptions define
an 18-parameter scenario for the fermion mass matrices for 18 experimentally
known observables. Performing a numerical analysis, we find excellent fits to
all observables in the case of both the normal and inverted neutrino mass
spectrum.Comment: 16 pages, two eps figure
Thermodynamic and gravitational instability on hyperbolic spaces
We study the properties of anti--de Sitter black holes with a Gauss-Bonnet
term for various horizon topologies (k=0, \pm 1) and for various dimensions,
with emphasis on the less well understood k=-1 solution. We find that the zero
temperature (and zero energy density) extremal states are the local minima of
the energy for AdS black holes with hyperbolic event horizons. The hyperbolic
AdS black hole may be stable thermodynamically if the background is defined by
an extremal solution and the extremal entropy is non-negative. We also
investigate the gravitational stability of AdS spacetimes of dimensions D>4
against linear perturbations and find that the extremal states are still the
local minima of the energy. For a spherically symmetric AdS black hole
solution, the gravitational potential is positive and bounded, with or without
the Gauss-Bonnet type corrections, while, when k=-1, a small Gauss-Bonnet
coupling, namely, \alpha << {l}^2 (where l is the curvature radius of AdS
space), is found useful to keep the potential bounded from below, as required
for stability of the extremal background.Comment: Shortened to match published (PRD) version, 18 pages, several eps
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