173 citations · 876 across the 16 of their papers we have counts for
17 papers
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…
Gravitational waves in non-singular string cosmologies
C. Cartier, E. J. Copeland, M. Gasperini
We study the evolution of tensor metric fluctuations in a class of non-singular models based on the string effective action, by including in the perturbation equation the higher-de…
Electroweak preheating on a lattice
A. Rajantie, P. M. Saffin, E. J. Copeland
In many inflationary models, a large amount of energy is transferred rapidly to the long-wavelength matter fields during a period of preheating after inflation. We study how this c…
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…
On non-perturbative corrections to the Kahler potential
T. Barreiro, B. de Carlos, E. J. Copeland
We present the results of a detailed investigation into the consequences of adding specific string motivated non-perturbative corrections to the usual tree level Kahler potential i…
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…
Electrically Charged Sphalerons
P. M. Saffin, E. J. Copeland
We investigate the possibility that the Higgs sector of the Weinberg-Salam model admits the existence of electrically charged, sphaleron states. Evidence is provided through an asy…
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…
Some aspects of thermal inflation: the finite temperature potential and topological defects
Tiago Barreiro, E. J. Copeland, David H. Lyth +1
Currently favoured extensions of the Standard Model typically contain `flaton fields' defined as fields with large vacuum expectation values (vevs) and almost flat potentials. If a…
How is a Closed String Loop like a Black Hole?
E. J. Copeland, Amitabha Lahiri
We demonstrate that under plausible assumptions the entropy and temperature associated with the small oscillations on a circular loop of radius and a black hole of mass $M=R/2G…
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…
Texture-Induced Microwave Background Anisotropies
Julian Borrill, Edmund J Copeland, Andrew R Liddle +2
We use numerical simulations to calculate the cosmic microwave background anisotropy induced by the evolution of a global texture field, with special emphasis on individual texture…
Reconstructing the Inflaton Potential---Perturbative Reconstruction to Second Order
Edmund Copeland, Edward W. Kolb, Andrew R. Liddle +1
One method to reconstruct the scalar field potential of inflation is a perturbative approach, where the values of the potential and its derivatives are calculated as an expansion i…
Reconstructing the Inflaton Potential---in Principle and in Practice
Edmund Copeland, Edward W. Kolb, Andrew R. Liddle +1
Generalizing the original work by Hodges and Blumenthal, we outline a formalism which allows one, in principle, to reconstruct the potential of the inflaton field from knowledge of…