25 research outputs found
Evaluating Sums over the Matsubara Frequencies
Perturbative calculations in field theory at finite temperature involve sums
over the Matsubara frequencies. Besides the usual difficulties that appear in
perturbative computations, these sums give rise to some new obstacles that are
carefully analized here. I present a fast and realible recipe to work out sums
over the Matsubara frequencies. As this algorithm leads to deal with very
cumbersome algebraic expressions, it has been written for computers by using
the symbolic manipulation program Mathematica. It is also shown this algorithm
to be self-consistent when it is applied to more than one loop computations.Comment: 10 page
Junctions and thin shells in general relativity using computer algebra I: The Darmois-Israel Formalism
We present the GRjunction package which allows boundary surfaces and
thin-shells in general relativity to be studied with a computer algebra system.
Implementing the Darmois-Israel thin shell formalism requires a careful
selection of definitions and algorithms to ensure that results are generated in
a straight-forward way. We have used the package to correctly reproduce a wide
variety of examples from the literature. We present several of these
verifications as a means of demonstrating the packages capabilities. We then
use GRjunction to perform a new calculation - joining two Kerr solutions with
differing masses and angular momenta along a thin shell in the slow rotation
limit.Comment: Minor LaTeX error corrected. GRjunction for GRTensorII is available
from http://astro.queensu.ca/~grtensor/GRjunction.htm
Maple V release 2 notes
SIGLEAvailable from Comsol AG, Wabern-Bern (Switzerland) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman