1,284 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 $N=1$, $D=4$ 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

### 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

### Construction of Low-Energy Effective Action in N=4 Super Yang-Mills Theories

We review a recent progress in constructing low-energy effective action in
N=4 super Yang-Mills theories. Using harmonic superspace approach we consider
N=4 SYM in terms of unconstrained N=2 superfield and apply N=2 background field
method to finding effective action for N=4 SU(n) SYM broken down to U(1)^(n-1).
General structure of leading low-energy corrections to effective action is
discussed.Comment: 8 pages, Based on a plenary talk given at the 9th International
Conference on Supersymmetry and Unification of Fundamental Interactions
(SUSY01), Dubna, Russia, June 11-17, 2001, to appear in the Proceeding

### 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

### Dynamical breaking of gauge symmetry in supersymmetric quantum electrodynamics in three-dimensional spacetime

The dynamical breaking of gauge symmetry in the supersymmetric quantum
electrodynamics in three-dimensional spacetime is studied at two-loop
approximation. At this level, the effective superpotential is evaluated in a
supersymmetric phase. At one-loop order, we observe a generation of the
Chern-Simons term due to a parity violating term present in the classical
action. At two-loop order, the scalar background superfield acquires a
nonvanishing vacuum expectation value, generating a mass term
$A^{\alpha}A_{\alpha}$ through Coleman-Weinberg mechanism. It is observed that
the mass of gauge superfield is predominantly an effect of the topological
Chern-Simons term.Comment: 10 pages, 2 figures, PRD versio

### 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.

### Ghost-Free Higher Derivative Quantum Gravity, the Hierarchy and the Cosmological Constant Problems

Proposing new solution problems of the hierarchy and smallness of the
cosmological constant using the Tev scale of the Standard Model in new
framework of the higher-order gravity.Comment: 5 pages referances added, published versio

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