182 research outputs found
Single Graviton Loop Contribution to the Self-Mass of a Massless, Conformally Coupled Scalar on de Sitter Background
We use a simplified formalism to re-compute the single graviton loop
contribution to the self-mass of a massless, conformally coupled scalar on de
Sitter background which was originally made by Boran, Kahya and Park [1-3]. Our
result resolves the problem with the flat space correspondence limit that was
pointed out by Fr\"ob [4]. We discuss how this computation will be used in a
long-term project to purge the linearized effective field equation of gauge
dependence.Comment: 26 pages, 1 figure, uses LaTeX 2e. Version 2 revised slightly for
publicatio
One loop graviton corrections to dynamical photons in de Sitter
We employ a recent, general gauge computation of the one loop graviton
contribution to the vacuum polarization on de Sitter to solve for one loop
corrections to the photon mode function. The vacuum polarization takes the form
of a gauge independent, spin 2 contribution and a gauge dependent, spin 0
contribution. We show that the leading secular corrections derive entirely from
the spin 2 contribution.Comment: 41 pages, no figures, uses LaTeX2
Graviton Loop Corrections to Vacuum Polarization in de Sitter in a General Covariant Gauge
We evaluate the one-graviton loop contribution to the vacuum polarization on
de Sitter background in a 1-parameter family of exact, de Sitter invariant
gauges. Our result is computed using dimensional regularization and fully
renormalized with BPHZ counterterms, which must include a noninvariant owing to
the time-ordered interactions. Because the graviton propagator engenders a
physical breaking of de Sitter invariance two structure functions are needed to
express the result. In addition to its relevance for the gauge issue this is
the first time a covariant gauge graviton propagator has been used to compute a
noncoincident loop. A number of identities are derived which should facilitate
further graviton loop computations.Comment: 61 pages, 1 figure, 11 tables, version 2 (63 pages) revised for
publication in CQ
Graviton Propagator in a 2-Parameter Family of de Sitter Breaking Gauges
We formulate the graviton propagator on de Sitter background in a 2-parameter
family of simple gauges which break de Sitter invariance. Explicit results are
derived for the first order perturbations in each parameter. These results
should be useful in computations to check for gauge dependence of graviton loop
corrections.Comment: 23 pages, 1 table, uses LaTeX2e, version 2 slightly revised for
publicatio
Breaking of scaling symmetry by massless scalar on de Sitter
We study the response of a classical massless minimally coupled scalar to a
static point scalar charge on de Sitter. By considering explicit solutions of
the problem we conclude that -- even though the dynamics formally admits
dilatation (scaling) symmetry -- the physical scalar field profile necessarily
breaks the symmetry. This is an instance of symmetry breaking in classical
physics due to large infrared effects. The gravitational backreaction, on the
other hand, does respect dilatation symmetry, making this an example of
symmetry non-inheritance phenomenon.Comment: 10 page
One-loop Graviton Corrections to Conformal Scalars on a de Sitter Background
We exploit a recent computation of one graviton loop corrections to the
self-mass [1] to quantum-correct the field equation for a massless, conformally
coupled scalar on a de Sitter background. With the obvious choice for the
finite part of the counterterm, we find that neither plane wave
mode functions nor the response to a point source acquires large infrared
logarithms. However, we do find a decaying logarithmic correction to the mode
function and a short distance logarithmic running of the potential in addition
to the power-law effect inherited from flat space.Comment: 25 pages, 2 figures; published versio
Explaining Large Electromagnetic Logarithms from Loops of Inflationary Gravitons
Recent progress on nonlinear sigma models on de Sitter background has
permitted the resummation of large inflationary logarithms by combining a
variant of Starobinsky's stochastic formalism with a variant of the
renormalization group. We reconsider single graviton loop corrections to the
photon wave function, and to the Coulomb potential, in light of these
developments. Neither of the two 1-loop results have a stochastic explanation,
however, the flow of a curvature-dependent field strength renormalization
explains their factors of . We speculate that the factor of
in the Coulomb potential should not be considered as a leading logarithm
effect.Comment: 22 pages, uses LaTeX2e, slightly revised for publicatio
- …