Edmund J. Copeland

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Macroscopic fundamental and Dirichlet strings have several potential instabilities: breakage, tachyon decays, and confinement by axion domain walls. We investigate the conditions under which metastable strings can exist, and we find that such strings are present in many models. There are various possibilities, the most notable being a network of (p, q)(More)
We present a detailed investigation of chaotic inflation models which feature two scalar fields, such that one field (the inflaton) rolls while the other is trapped in a false vacuum state. The false vacuum becomes unstable when the magnitude of the inflaton field falls below some critical value, and a first or second order transition to the true vacuum(More)
We present a phase-plane analysis of cosmologies containing a barotropic fluid with equation of state pγ = (γ − 1)ργ, plus a scalar field φ with an exponential potential V ∝ exp(−λκφ) where κ = 8πG. In addition to the well-known inflationary solutions for λ < 2, there exist scaling solutions when λ > 3γ in which the scalar field energy density tracks that(More)
We consider the construction of inverted hybrid inflation models in which the vacuum energy during inflation is at the TeV scale, and the inflaton couples to the Higgs field. Such models are of interest in the context of some recently proposed models of electroweak baryogenesis. We demonstrate how constraints on these models arise from quantum corrections,(More)
Aspects of superstring cosmology are reviewed with an emphasis on the cosmological implications of duality symmetries in the theory. The string effective actions are summarized and toroidal compactification to four dimensions reviewed. Global symmetries that arise in the compactification are discussed and the duality relationships between the string(More)
We study the dynamics of Nambu-Goto strings with junctions at which three strings meet. In particular, we exhibit one simple exact solution and examine the process of intercommuting of two straight strings in which they exchange partners but become joined by a third string. We show that there are important kinematical constraints on this process. The(More)
We extend and develop our previous work on the evolution of a network of cosmic strings. The new treatment is based on an analysis of the probability distribution of the end-to-end distance, or extension, of a randomly chosen segment of left-moving string of given length. The description involves three distinct length scales: ξ, related to the overall(More)
Scalar field theory has become the generic playground for building cosmological models related to particle physics, in particular for obtaining inflationary cosmologies. One such class of models involves exponential potentials @exp(A16p/pmPl 2 f)# , which lead to power law inflation, a }t, with p.1, for sufficiently flat potentials @1–3#. A number of(More)
We examined steady-state levels of mRNA encoding type IV collagen, B1 chain of laminin, and the basement membrane heparan sulfate proteoglycan in the kidney cortex of a mouse model (KKAy) of non-insulin-dependent diabetes. mRNAs encoding laminin B1 and the proteoglycan were unchanged in kidneys taken from diabetic mice with demonstrable basement membrane(More)