Preheating and phase transitions in gauge theories

It has recently been suggested that the baryon washout problem of the standard electroweak baryogenesis scenario could be avoided if inflation ends with a period of parametric resonance at a low enough energy density. I present results of numerical simulations in which this process was studied in the Abelian Higgs model. Our results show that because of the masslessness of the gauge field, the parametric resonance takes place naturally, and that the system reaches a quasi-equilibrium state in which the long-wavelength part of the spectrum has a high effective temperature. This enhances baryon number violation and makes baryogenesis more efficient.Comment: Talk given at SEWM2000. 5 pages, 1 figur

Formation of Magnetic Monopoles in Hot Gauge Theories

In this talk, I discuss the formation of magnetic monopoles in a phase transition from the confining SU(2) phase to the Coulomb phase in a hot Georgi-Glashow model. I argue that monopoles are formed from long-wavelength thermal fluctuations, which freeze out after the phase transition.Comment: 5 pages, talk given at Strong and Electroweak Matter 2002, Heidelberg, October 2-5, 200

Defect formation in the early universe

Topological defects are common in many everyday systems. In general, they appear if a symmetry is broken at a rapid phase transition. In this article, I explain why it is believed that they should have also been formed in the early universe and how that would have happened. If topological defects are found, this will provide a way to study observationally the first fractions of a second after the Big Bang, but their apparent absence can also tell us many things about the early universe.Comment: 26 pages, 10 figures. Updated to match the version published in Contemporary Physics (http://taylorandfrancis.metapress.com/link.asp?id=dcvj45hv41kr7xf7

Non-equilibrium dynamics of hot Abelian Higgs model

The real-time dynamics of finite-temperature gauge theories can be approximated, to leading-order accuracy in the coupling constants, by a classical field theory with the hard thermal loop Lagrangian. I show how this approach can be used in numerical lattice simulations to study dynamics of the Abelian Higgs model in or slightly out of equilibrium.Comment: 4 pages, talk given at COSMO' 99, Trieste, Italy, September 27 - October 2, 199

Phase transition dynamics in the hot Abelian Higgs model

We present a detailed numerical study of the equilibrium and non-equilibrium dynamics of the phase transition in the finite-temperature Abelian Higgs model. Our simulations use classical equations of motion both with and without hard-thermal-loop corrections, which take into account the leading quantum effects. From the equilibrium real-time correlators, we determine the Landau damping rate, the plasmon frequency and the plasmon damping rate. We also find that, close to the phase transition, the static magnetic field correlator shows power-law magnetic screening at long distances. The information about the damping rates allows us to derive a quantitative prediction for the number density of topological defects formed in a phase transition. We test this prediction in a non-equilibrium simulation and show that the relevant time scale for defect formation is given by the Landau damping rate.Comment: 22 pages, 3 figure

Lattice calculation of non-Gaussianity from preheating

If light scalar fields are present at the end of inflation, their non-equilibrium dynamics such as parametric resonance or a phase transition can produce non-Gaussian density perturbations. We show how these perturbations can be calculated using non-linear lattice field theory simulations and the separate universe approximation. In the massless preheating model, we find that some parameter values are excluded while others lead to acceptable but observable levels of non-Gaussianity. This shows that preheating can be an important factor in assessing the viability of inflationary models.Comment: 4 pages, 1 figure; erratum adde