387 research outputs found
Lorentz invariance of effective strings
Starting from a Poincar\'e invariant field theory of a real scalar field with
interactions governed by a double-well potential in 2+1 dimensions, the Lorentz
representation induced on the collective coordinates describing low-energy
excitations about an effective string background is derived. In this
representation, Lorentz transformations are given in terms of an infinite
series, in powers of derivatives along the worldsheet. Transformations that act
on the direction transverse to the string worldsheet involve a universal
dimension term. As a consequence, Lorentz invariance holds in this theory
of long effective strings due to cancellations in the action between irrelevant
terms and the dimension two term that describes free massless scalar fields in
two dimensions. (in plain tex, no macropackages necessary)Comment: 9 page
Supersymmetric vertex algebras
We define and study the structure of SUSY Lie conformal and vertex algebras.
This leads to effective rules for computations with superfields.Comment: 71 page
Power spectrum and correlation function errors: Poisson vs. Gaussian shot noise
Poisson distributed shot noise is normally considered in the Gaussian limit
in cosmology. However, if the shot noise is large enough and the correlation
function/power spectrum conspires, the Gaussian approximation mis-estimates the
errors and their covariance significantly. The power spectrum, even for
initially Gaussian densities,acquires cross correlations which can be large,
while the change in the correlation function error matrix is diagonal except at
zero separation. Two and three dimensional power law correlation function and
power spectrum examples are given. These corrections appear to have a large
effect when applied to galaxy clusters, e.g. for SZ selected galaxy clusters in
2 dimensions. This can increase the error estimates for cosmological parameter
estimation and consequently affect survey strategies, as the corrections are
minimized for surveys which are deep and narrow rather than wide and shallow.
In addition, a rewriting of the error matrix for the power spectrum/correlation
function is given which eliminates most of the Bessel function dependence (in
two dimensions) and all of it (in three dimensions), which makes the
calculation of the error matrix more tractable. This applies even when the shot
noise is in the (usual) Gaussian limit.Comment: 22 pages, 4 figures, 3 equations corrected/figures updated, results
unchange
Electrodynamics with radiation reaction
The self force of electrodynamics is derived from a scalar field. The
resulting equation of motion is free of all of the problems that plague the
Lorentz Abraham Dirac equation. The age-old problem of a particle in a constant
field is solved and the solution has intuitive appeal.Comment: 5 page
Gauged Inflation
We propose a model for cosmic inflation which is based on an effective
description of strongly interacting, nonsupersymmetric matter within the
framework of dynamical Abelian projection and centerization. The underlying
gauge symmetry is assumed to be with . Appealing to a
thermodynamical treatment, the ground-state structure of the model is
classically determined by a potential for the inflaton field (dynamical
monopole condensate) which allows for nontrivially BPS saturated and thereby
stable solutions. For this leads to decoupling of gravity from the
inflaton dynamics. The ground state dynamics implies a heat capacity for the
vacuum leading to inflation for temperatures comparable to the mass scale
of the potential. The dynamics has an attractor property. In contrast to the
usual slow-roll paradigm we have during inflation. As a consequence,
density perturbations generated from the inflaton are irrelevant for the
formation of large-scale structure, and the model has to be supplemented with
an inflaton independent mechanism for the generation of spatial curvature
perturbations. Within a small fraction of the Hubble time inflation is
terminated by a transition of the theory to its center symmetric phase. The
spontaneously broken symmetry stabilizes relic vector bosons in the
epochs following inflation. These heavy relics contribute to the cold dark
matter of the universe and potentially originate the UHECRs beyond the GZK
bound.Comment: 23 pages, 4 figures, subsection added, revision of text, to app. in
PR
SUSY vertex algebras and supercurves
This article is a continuation of math.QA/0603633 Given a strongly conformal
SUSY vertex algebra V and a supercurve X we construct a vector bundle V_X on X,
the fiber of which, is isomorphic to V. Moreover, the state-field
correspondence of V canonically gives rise to (local) sections of these vector
bundles. We also define chiral algebras on any supercurve X, and show that the
vector bundle V_X, corresponding to a SUSY vertex algebra, carries the
structure of a chiral algebra.Comment: 50 page
Cosmological Perturbations from the No Boundary Euclidean Path Integral
We compute, from first principles, the quantum fluctuations about instanton
saddle points of the Euclidean path integral for Einstein gravity coupled to a
scalar field. The Euclidean two-point correlator is analytically continued into
the Lorentzian region where it describes the quantum mechanical vacuum
fluctuations in the state described by no boundary proposal initial conditions.
We concentrate on the density perturbations in open inflationary universes
produced from cosmological instantons, describing the differences between
non-singular Coleman-De Luccia and singular Hawking-Turok instantons. We show
how the Euclidean path integral uniquely specifies the fluctuations in both
cases.Comment: 21 pages, RevTex file, including five postscript figure file
Two-dimensional superstrings and the supersymmetric matrix model
We present evidence that the supersymmetric matrix model of Marinari and
Parisi represents the world-line theory of N unstable D-particles in type II
superstring theory in two dimensions. This identification suggests that the
matrix model gives a holographic description of superstrings in a
two-dimensional black hole geometry.Comment: 22 pages, 2 figures; v2: corrected eqn 4.6; v3: corrected appendices
and discussion of vacua, added ref
Particle physics models of inflation
Inflation models are compared with observation on the assumption that the
curvature perturbation is generated from the vacuum fluctuation of the inflaton
field. The focus is on single-field models with canonical kinetic terms,
classified as small- medium- and large-field according to the variation of the
inflaton field while cosmological scales leave the horizon. Small-field models
are constructed according to the usual paradigm for beyond Standard Model
physicsComment: Based on a talk given at the 22nd IAP Colloquium, ``Inflation +25'',
Paris, June 2006 Curve omitted from final Figur
Wall fluctuation modes and tensor CMB anisotropy in open inflation models
We calculate the spectrum of large angle cosmic microwave background (CMB)
anisotropies due to quantum fluctuations of the gravitational wave modes in
one-bubble open inflation models. We find the bubble-wall fluctuation modes,
which had been thought to exist discretely in previous analyses, are actually
contained in the continuous spectrum of gravitational wave modes when the
gravitational coupling is correctly taken into account. Then we find that the
spectrum of the tensor CMB anisotropy can be decomposed into the part due to
the wall fluctuation modes and that due to the usual gravitational wave modes
in a way which is almost model-independent, even when the gravitational
coupling is strong. We also discuss observational constraints on the model
parameters. We find that an appreciable portion of the parameter space is
excluded but the remaining allowable region is still wide enough to leave the
one-bubble scenario viable.Comment: 12 pages revtex file, 9 postscript figure
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