10,482 research outputs found
Effective CP violation in the Standard Model
We study the strength of effective CP violation originating from the CKM
matrix in the effective action obtained by integrating out the fermions in the
Standard Model. Using results obtained by Salcedo for the effective action in a
general chiral gauge model, we find that there are no CKM CP-violating terms to
fourth order in a gauge-covariant derivative expansion that is non-perturbative
in the Higgs field. The details of the calculation suggest that, at zero
temperature, the strength of CP violation is approximately independent of the
overall scale of the Yukawa couplings. Thus, order of magnitude estimates based
on Jarlskog's invariant could be too small by a factor of about 10^{17}.Comment: 19 pages, no figure
Microwave background anisotropies in quasiopen inflation
Quasiopenness seems to be generic to multi-field models of single-bubble open
inflation. Instead of producing infinite open universes, these models actually
produce an ensemble of very large but finite inflating islands. In this paper
we study the possible constraints from CMB anisotropies on existing models of
open inflation. The effect of supercurvature anisotropies combined with the
quasiopenness of the inflating regions make some models incompatible with
observations, and severely reduces the parameter space of others. Supernatural
open inflation and the uncoupled two-field model seem to be ruled out due to
these constraints for values of . Others, such as the
open hybrid inflation model with suitable parameters for the slow roll
potential can be made compatible with observations.Comment: 19 pages, ReVTeX, 10 figures inserted with eps
Complete power spectrum for an induced gravity open inflation model
We study the phenomenological constraints on a recently proposed model of
open inflation in the context of induced gravity. The main interest of this
model is the relatively small number of parameters, which may be constrained by
many different types of observation. We evaluate the complete spectrum of
density perturbations, which contains continuum sub-curvature modes, a discrete
super curvature mode, and a mode associated with fluctuations in the bubble
wall. From these, we compute the angular power spectrum of temperature
fluctuations in the microwave background, and derive bounds on the parameters
of the model so that the predicted spectrum is compatible with the observed
anisotropy of the microwave background and with large-scale structure
observations. We analyze the matter era and the approach of the model to
general relativity. The model passes all existing constraints.Comment: 12 pages RevTeX file with four figures incorporated (uses RevTeX and
epsf). Also available by e-mailing ARL, or by WWW at
http://star-www.maps.susx.ac.uk/papers/early_papers.html Only change is
additional reference
Metric perturbations in two-field inflation
We study the metric perturbations produced during inflation in models with
two scalar fields evolving simultaneously. In particular, we emphasize how the
large-scale curvature perturbation on fixed energy density
hypersurfaces may not be conserved in general for multiple field inflation due
to the presence of entropy as well as adiabatic fluctuations. We show that the
usual method of solving the linearized perturbation equations is equivalent to
the recently proposed analysis of Sasaki and Stewart in terms of the perturbed
expansion along neighboring trajectories in field-space. In the case of a
separable potential it is possible to compute in the slow-roll approximation
the spectrum of density perturbations and gravitational waves at the end of
inflation. In general there is an inequality between the ratio of tensor to
scalar perturbations and the tilt of the gravitational wave spectrum, which
becomes an equality when only adiabatic perturbations are possible and
is conserved.Comment: RevTex, 9 pages, 1 uuencoded figure appended, also available on WWW
via http://star.maps.susx.ac.uk/index.htm
Bubble fluctuations in inflation
In the context of the open inflationary universe, we calculate the amplitude
of quantum fluctuations which deform the bubble shape. These give rise to
scalar field fluctuations in the open Friedman-Robertson-Walker universe which
is contained inside the bubble. One can transform to a new gauge in which
matter looks perfectly smooth, and then the perturbations behave as tensor
modes (gravitational waves of very long wavelength). For , where
is the density parameter, the microwave temperature anisotropies
produced by these modes are of order . Here, is the expansion rate during inflation, is
the intrinsic radius of the bubble at the time of nucleation, is the
bubble wall tension and labels the different multipoles (). The
gravitational backreaction of the bubble has been ignored. In this
approximation, , and the new effect can be much larger than the
one due to ordinary gravitational waves generated during inflation (unless, of
course, gets too close to one, in which case the new effect
disappears).Comment: 17 pages, 3 figs, LaTeX, epsfig.sty, available at
ftp://ftp.ifae.es/preprint/ft/uabft387.p
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