5 research outputs found
Self-forces in the Spacetime of Multiple Cosmic Strings
We calculate the electromagnetic self-force on a stationary linear
distribution of four-current in the spacetime of multiple cosmic strings. It is
shown that if the current is infinitely thin and stretched along a line which
is parallel to the strings the problem admits an explicit solution.Comment: This paper has been produced in Latex format and has 18 page
The gauge invariant effective potential: equilibrium and non-equilibrium aspects
We propose a gauge invariant formulation of the effective potential in terms
of a gauge invariant order parameter, for the Abelian Higgs model. The one-loop
contribution at zero and finite temperature is computed explicitly, and the
leading terms in the high temperature expansion are obtained. The result is
contrasted to the effective potential obtained in several covariant
gauge-fixing schemes, and the gauge invariant quantities that can be reliably
extracted from these are identified. It is pointed out that the gauge invariant
effective potential in the one-loop approximation is complex for {\em all
values} of the order parameter between the maximum and the minimum of the tree
level potential, both at zero and non-zero temperature. The imaginary part is
related to long-wavelength instabilities towards phase separation. We study the
real-time dynamics of initial states in the spinodal region, and relate the
imaginary part of the effective potential to the growth rate of equal-time
gauge invariant correlation functions in these states. We conjecture that the
spinodal instabilities may play a role in non-equilibrium processes {\em
inside} the nucleating bubbles if the transition is first order.Comment: 27 pages revtex 3.0, no figures; one reference adde
Quantum corrections to the kinetic term in the Randall-Sundrum model
The effective action of the radion in the Randall-Sundrum model is analysed.
Fine tunings are needed to obtain the observed mass hierarchy and an invisible
radion. since the kinetic terms are important for determining the radion mass,
the finite quantum corrections from massless conformally coupled fermions are
analysed and found to vanish at one loop order.Comment: 10 pages, 3 figures, JHEP LaTeX, with correction
Quantum reparametrizations in the two-dimensional gravity: a look from 2+ dimensions
We discuss the structure of one-loop counterterms for the two-dimensional
theory of gravitation in the covariant scheme and study the effect of quantum
reparametrizations. Some of them are shown to be equivalent to the introduction
of -dimensional terms into the initially 2-dimensional theory. We
also argue that the -function for the Einstein constant has a
non-trivial ultraviolet stable point beyond two dimensions.Comment: 16 page