2,434 research outputs found
On structure of effective action in four-dimensional quantum dilaton supergravity
A general structure of effective action in new chiral superfield model
associated with , supergravity is investigated. This model
corresponds to finite quantum field theory and does not demand the
regularization and renormalization at effective action calculation. It is shown
that in local approximation the effective action is defined by two objects
called general superfield effective lagrangian and chiral superfield effective
lagrangian. A proper-time method is generalized for calculation of these two
effective lagrangians in superfield manner. Power expansion of the effective
action in supercovariant derivatives is formulated and the lower terms of such
an expansion are calculated in explicit superfield form
Generalized modified gravity with the second order acceleration equation
In the theories of generalized modified gravity, the acceleration equation is
generally fourth order. So it is hard to analyze the evolution of the Universe.
In this paper, we present a class of generalized modified gravity theories
which have the acceleration equation of second order derivative. Then both the
cosmic evolution and the weak-field limit of the theories are easily
investigated. We find that not only the Big-bang singularity problem but also
the current cosmic acceleration problem could be easily dealt with.Comment: 8 pages, 2 figures. To appear in Phys. Rev.
Supersymmetric Nambu-Jona-Lasinio Model in an External Gravitational Field
We investigate the effect of an external gravitational fields to the chiral
symmetry breaking in the SUSY (supersymmetric) NJL (Nambu-Jona-Lasinio) model
non-minimally interacting with external supergravity. Evaluating the effective
potential in the leading order of the -expansion and in the linear
curvature approximation it is found the possibility of the chiral symmetry
breaking in the SUSY NJL model in an external gravitational fields. In the
broken phase the dynamically generated mass is analytically and numerically
calculated.Comment: 8 pages, Latex, epic.sty and eepic.sty are use
Constructing the Cubic Interaction Vertex of Higher Spin Gauge Fields
We propose a method of construction of a cubic interaction in massless Higher
Spin gauge theory both in flat and in AdS space-times of arbitrary dimensions.
We consider a triplet formulation of the Higher Spin gauge theory and
generalize the Higher Spin symmetry algebra of the free model to the
corresponding algebra for the case of cubic interaction. The generators of this
new algebra carry indexes which label the three Higher Spin fields involved
into the cubic interaction. The method is based on the use of oscillator
formalism and on the Becchi-Rouet-Stora-Tyutin (BRST) technique. We derive
general conditions on the form of cubic interaction vertex and discuss the
ambiguities of the vertex which result from field redefinitions. This method
can in principle be applied for constructing the Higher Spin interaction vertex
at any order. Our results are a first step towards the construction of a
Lagrangian for interacting Higher Spin gauge fields that can be holographically
studied.Comment: Published Version; comments added in introduction; minor typos and
references correcte
Covariant power-counting renormalizable gravity: Lorentz symmetry breaking and accelerating early-time FRW universe
We continue the study of covariant power-counting renormalizable gravity
constrained by scalar Lagrange multiplier. Lorentz symmetry breaking is
investigated in such a theory in comparison with the one in ghost condensation
model. Covariant power-counting renormalizable vector gravity which is
invariant under gauge symmetry is proposed. Several forms of vector
Lagrange multiplier in this theory are discussed. It is shown that covariant
scalar/vector gravity under consideration may have power-law or de Sitter
accelerating cosmological solution corresponding to inflationary era. Simplest
black hole solution is obtained and dispersion relations for graviton are
presented.Comment: LaTeX, 13 page
Back reaction of vacuum and the renormalization group flow from the conformal fixed point
We consider the GUT-like model with two scalar fields which has infinitesimal
deviation from the conformal invariant fixed point at high energy region. In
this case the dominating quantum effect is the conformal trace anomaly and the
interaction between the anomaly-generated propagating conformal factor of the
metric and the usual dimensional scalar field. This interaction leads to the
renormalization group flow from the conformal point. In the supersymmetric
conformal invariant model such an effect produces a very weak violation of
sypersymmetry at lower energies.Comment: 15 pages, LaTex, ten figures, uuencoded fil
On a possibility to construct gauge invariant quantum formulation for non-gauge classical theory
A non-gauge dynamical system depending on parameters is considered. It is
shown that these parameters can have such values that corresponding canonically
quantized theory will be gauge invariant. The equations allowing to find these
values of parameters are derived. The prescription under consideration is
applied to obtaining the equation of motion for tachyon background field in
closed bosonic string theory.Comment: 19 pages, LaTeX file, minor mistakes correcte
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