Poul Olesen

An unstable Yang-Mills field mode

Abstract We discuss asymptotic freedom as an aspect of the response of a charged vector field to an external homogeneous magnetic field. It is shown that there exists an unstable mode of the field. The vacuum polarization is investigated. For lar is a “phase transition”: the result of applying an external field and switching this field off is not equivalent to having no field at all. The vacuum polarization of the unstable mode corresponds to the self energy of a tachyon in 1 + 1 dimension.

Large-scale magnetic fields from hydromagnetic turbulence in the very early universe.

We investigate hydromagnetic turbulence of primordial magnetic fields using magnetohydrodynamics (MHD) in an expanding universe. We present the basic, covariant MHD equations, find solutions for MHD waves in the early universe, and investigate the equations numerically for random magnetic fields in two spatial dimensions. We find the formation of magnetic structures at larger and larger scales as time goes on. In three dimensions we use a cascade (shell) model that has been rather successful in the study of certain aspects of hydrodynamic turbulence. Using such a model we find that after ensuremath{sim}

A Condensate Solution of the Electroweak Theory Which Interpolates Between the Broken and the Symmetric Phase

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A Magnetic Condensate Solution of the Classical Electroweak Theory

times the initial time the scale of the magnetic field fluctuation (in the comoving frame) has increased by 4-5 orders of magnitude as a consequence of an inverse cascade effect (i.e., transfer of energy from smaller to larger scales). Thus at large scales primordial magnetic fields are considerably stronger than expected from considerations which do not take into account the effects of MHD turbulence.

Electric Vortex Lines From the {Yang-Mills} Theory

We discuss a magnetic type solution of the classical electroweak equations with the property that for fields larger than mw2/e a W- and Z-condensate is formed. When the average magnetic field reaches the value mw2/e cos2 θ, the SU(2) × y(1) symmetry is restored. We compare to the finite temperature case. It is mentioned that large magnetic fields of order mw2/e (realized e.g. near the superconducting cosmic string) can actually be achieved in earth-bound laboratories as the field surrounding quarks in e.g. proton-proton collisions with more than 1 TeV energy. However, we do not know if the field lasts long enough to produce a W-Z plasma.

Primordial Magnetic Field and Non-Gaussianity of the One-Year Wilkinson Microwave Anisotropy Probe Data

Abstract According to the electroweak theory a large homogeneous magnetic field exceeding m w 2 / e is unstable. We present a different solution of the classical electroweak field equations which is a condensate of magnetic fluxes induced by an anti-Lenz current of the chargedvector bosons. The anti-Lenz mechanism is a consequence of asymptotic freedom. The range of validity of this solution depends on the Weinberg angle θ.

Confinement and random fluxes

Abstract We develop the dynamics of an unstable Yang-Mills field mode previously found by us. We argue that this unstable mode corresponds to the transition to a state where electric vortex lines are created.

TOWARDS A NON-PERTURBATIVE FORMULATION OF IIB SUPERSTRINGS BY MATRIX MODELS

Alfven turbulence caused by statistically isotropic and homogeneous primordial magnetic field induces correlations in the cosmic microwave background (CMB) anisotropies. The correlations are specifically between the spherical harmonic modes al-1,m and al+1,m. In this paper we approach this issue from phase analysis of the CMB maps derived from the WMAP data sets. Using circular statistics and return phase mapping, we examine phase correlation of Δl = 2 for the primordial non-Gaussianity caused by the Alfven turbulence at the epoch of recombination. Our analyses show that such specific features from the power-law Alfven turbulence do not contribute significantly in the phases of the maps and could not be a source of primordial non-Gaussianity of the CMB.

Dual models as saddle point approximations to Polyakov's quantized string

Abstract We discuss the concept of random fluxes in a confining QCD vacuum. It is shown that a necessary and sufficient condition for confinement is that a certain flux must be independently distributed [eq. (3.7)] over the minimal surface spanned by the Wilson loop.

Remarks on the heavy quark potential in the supergravity approach

Abstract We address the problem of a non-perturbative formulation of superstring theory by means of the recently proposed matrix models. For the model by Ishibashi, Kawai, Kitazawa and Tsuchiya (IKKT), we perform one-loop calculation of the interaction between operator-like solutions identified with D-brane configurations of type IIB superstrings (in particular, for parallel moving and rotated static p-branes). Comparing to the superstring calculations, we show that the matrix model reproduces the superstring results only at small velocities or large distances, corresponding to keeping only the lowest mass open-string modes. We propose a modification of the IKKT matrix model introducing an integration over an additional Hermitian matrix required to have positive definite eigenvalues, which is similar to the square root of the metric in the continuum Schild formulation of IIB superstrings. We show that for this new matrix action the Nambu-Goto version of the Green-Schwarz action is reproduced even at quantum level.