173 citations · 876 across the 16 of their papers we have counts for
8 papers · 1 filter
Cosmological perturbations and the transition from contraction to expansion
C. Cartier, R. Durrer, E. J. Copeland
We investigate both analytically and numerically the evolution of scalar perturbations generated in models which exhibit a smooth transition from a contracting to an expanding Frie…
Five-Dimensional Moving Brane Solutions with Four-Dimensional Limiting Behaviour
Ed Copeland, James Gray, Andre Lukas +1
Under certain conditions some solutions to five-dimensional heterotic M-theory can be accurately described by the four-dimensional action of the theory - they have a four-dimension…
Instantons from Low Energy String Actions
P. M. Saffin, Anupam Mazumdar, E. J. Copeland
We look for instanton solutions in a class of two scalar field gravity models, which includes the low energy string action in four dimensions. In models where the matter field has…
Graceful Exit in String Cosmology
Ram Brustein, Richard Madden
The graceful exit transition from a dilaton-driven inflationary phase to a decelerated Friedmann-Robertson-Walker era requires certain classical and quantum corrections to the stri…
Cosmology of the type IIB superstring
E. J. Copeland, James E. Lidsey, David Wands
The continuous and discrete symmetries of a dimensionally reduced type IIB superstring action are employed to generate four-dimensional cosmological solutions with non-trivial Neve…
Symmetries for generating string cosmologies
E. J. Copeland, James E. Lidsey, David Wands
We discuss the symmetry properties of the low-energy effective action of the type IIB superstring that may be employed to derive four-dimensional solutions. A truncated effective a…
Vacuum fluctuations in axion-dilaton cosmologies
E. J. Copeland, Richard Easther, David Wands
We study axion-dilaton cosmologies derived from the low-energy string effective action. We present the classical homogeneous Friedmann-Robertson-Walker solutions and derive the sem…
String Cosmology with a Time-Dependent Antisymmetric Tensor Potential
E. J. Copeland, Amitabha Lahiri, David Wands
We present a class of exact solutions for homogeneous, anisotropic cosmologies in four dimensions derived from the low-energy string effective action including a homogeneous dilato…