157 research outputs found
Scalar-Tensor Gravity Theory For Dynamical Light Velocity
A gravity theory is developed with the metric . In the present universe the
additional contribution from the scalar field in the metric
can generate an acceleration in the expansion of the universe, without negative
pressure and with a zero cosmological constant. In this theory, gravitational
waves will propagate at a different speed from non-gravitational waves. It is
suggested that gravitational wave experiments could test this observational
signature.Comment: 14 pages latex file. Additional material added. Accepted for
publication in Physics Letters
Nonsymmetric Gravitational Theory
A new version of nonsymmetric gravitational theory is presented. The field
equations are expanded about the Minkowski metric, giving in lowest order the
linear Einstein field equations and massive Proca field equations for the
antisymmetric field . An expansion about an arbitrary Einstein
background metric yields massive Proca field equations with couplings to only
physical modes. It follows that the new version of NGT is free of ghost poles,
tachyons and higher-order poles and there are no problems with asymptotic
boundary conditions. A static spherically symmetric solution of the field
equations in the short-range approximation is everywhere regular and does not
contain a black hole event horizon.Comment: 11 pages plain TeX. TeX macrofile included. Corrections in formula
LIGO GW150914 and GW151226 gravitational wave detection and generalized gravitation theory (MOG)
AbstractThe nature of gravitational waves in a generalized gravitation theory is investigated. The linearized field equations and the metric tensor quadrupole moment power and the decrease in radius of an inspiralling binary system of two compact objects are derived. The generalized Kerr metric describing a spinning black hole is determined by its mass M and the spin parameter a=cS/GM2. The LIGO-Virgo collaboration data is fitted with smaller binary black hole masses in agreement with the current electromagnetic, observed X-ray binary upper bound for a black hole mass, M≲10M⊙
Noncommutative and Non-Anticommutative Quantum Field Theory
A noncommutative and non-anticommutative quantum field theory is formulated
in a superspace, in which the superspace coordinates satisfy noncommutative and
non-anticommutative relations. A perturbative scalar field theory is
investigated in which only the non-anticommutative algebraic structure is kept,
and one loop diagrams are calculated and found to be finite due to the damping
caused by a Gaussian factor in the propagator.Comment: 12 pages LaTex. No figures. Revised text. Conclusions remain the
same. Misprint in Eq.(31) correcte
Noncommutative Quantum Gravity
The possible role of gravity in a noncommutative geometry is investigated.
Due to the Moyal *-product of fields in noncommutative geometry, it is
necessary to complexify the metric tensor of gravity. We first consider the
possibility of a complex Hermitian, nonsymmetric and discuss the
problems associated with such a theory. We then introduce a complex symmetric
(non-Hermitian) metric, with the associated complex connection and curvature,
as the basis of a noncommutative spacetime geometry. The spacetime coordinates
are in general complex and the group of local gauge transformations is
associated with the complex group of Lorentz transformations CSO(3,1). A real
action is chosen to obtain a consistent set of field equations. A Weyl
quantization of the metric associated with the algebra of noncommuting
coordinates is employed.Comment: 13 pages LaTex. Changes to text and new text added. To be published
in Physics Letters
Ultraviolet Complete Electroweak Model Without a Higgs Particle
An electroweak model with running coupling constants described by an energy
dependent entire function is utraviolet complete and avoids unitarity
violations for energies above 1 TeV. The action contains no physical scalar
fields and no Higgs particle and the physical electroweak model fields are
local and satisfy microcausality. The and masses are compatible with a
symmetry breaking , which
retains a massless photon. The vertex couplings possess an energy scale
TeV predicting scattering amplitudes that can be tested at the
LHC.Comment: 19 pages, no figures, LaTex file. Equation and text corrected.
Reference added. Results remain the same. Final version published in European
Physics Journal Plus, 126 (2011
A scalar-tensor cosmological model with dynamical light velocity
The dynamical consequences of a bimetric scalar-tensor theory of gravity with
a dynamical light speed are investigated in a cosmological setting. The model
consists of a minimally-coupled self-gravitating scalar field coupled to
ordinary matter fields in the standard way through the metric:
\metric_{\mu\nu}+B\partial_\mu\phi\partial_\nu\phi. We show that in a
universe with matter that has a radiation-dominated equation of state, the
model allows solutions with a de Sitter phase that provides sufficient
inflation to solve the horizon and flatness problems. This behaviour is
achieved without the addition of a potential for the scalar field, and is shown
to be largely independent of its introduction. We therefore have a model that
is fundamentally different than the potential-dominated, slowly-rolling scalar
field of the standard models inflationary cosmology. The speed of gravitational
wave propagation is predicted to be significantly different from the speed of
matter waves and photon propagation in the early universe.Comment: 12 pages, uses amsart and amssymb. Minor corrections, to appear in
Phys. Lett.
Resolving Curvature Singularities in Holomorphic Gravity
We formulate holomorphic theory of gravity and study how the holomorphy
symmetry alters the two most important singular solutions of general
relativity: black holes and cosmology. We show that typical observers (freely)
falling into a holomorphic black hole do not encounter a curvature singularity.
Likewise, typical observers do not experience Big Bang singularity. Unlike
Hermitian gravity \cite{MantzHermitianGravity}, Holomorphic gravity does not
respect the reciprocity symmetry and thus it is mainly a toy model for a
gravity theory formulated on complex space-times. Yet it is a model that
deserves a closer investigation since in many aspects it resembles Hermitian
gravity and yet calculations are simpler. We have indications that holomorphic
gravity reduces to the laws of general relativity correctly at large distance
scales.Comment: 14 pages, 7 figure
Observational Constraints on the Modified Gravity Model (MOG) Proposed by Moffat: Using the Magellanic System
A simple model for the dynamics of the Magellanic Stream (MS), in the
framework of modified gravity models is investigated. We assume that the galaxy
is made up of baryonic matter out of context of dark matter scenario. The model
we used here is named Modified Gravity (MOG) proposed by Moffat (2005). In
order to examine the compatibility of the overall properties of the MS under
the MOG theory, the observational radial velocity profile of the MS is compared
with the numerical results using the fit method. In order to obtain
the best model parameters, a maximum likelihood analysis is performed. We also
compare the results of this model with the Cold Dark Matter (CDM) halo model
and the other alternative gravity model that proposed by Bekenstein (2004), so
called TeVeS. We show that by selecting the appropriate values for the free
parameters, the MOG theory seems to be plausible to explain the dynamics of the
MS as well as the CDM and the TeVeS models.Comment: 14 pages, 3 Figures, accepted in Int. J. Theor. Phy
Comments on "Note on varying speed of light theories"
In a recent note Ellis criticizes varying speed of light theories on the
grounds of a number of foundational issues. His reflections provide us with an
opportunity to clarify some fundamental matters pertaining to these theories
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