4,070 research outputs found
One Loop Corrected Mode Functions for SQED during Inflation
We solve the one loop effective scalar field equations for spatial plane
waves in massless, minimally coupled scalar quantum electrodynamics on a
locally de Sitter background. The computation is done in two different gauges:
a non-de Sitter invariant analogue of Feynman gauge, and in the de Sitter
invariant, Lorentz gauge. In each case our result is that the finite part of
the conformal counterterm can be chosen so that the mode functions experience
no significant one loop corrections at late times. This is in perfect agreement
with a recent, all orders stochastic prediction.Comment: 26 pages, uses LaTeX 2 epsilon, no figures, version 2 has an updated
reference lis
Scalar Field Equations from Quantum Gravity during Inflation
We exploit a previous computation of the self-mass-squared from quantum
gravity to include quantum corrections to the scalar evolution equation. The
plane wave mode functions are shown to receive no significant one loop
corrections at late times. This result probably applies as well to the inflaton
of scalar-driven inflation. If so, there is no significant correction to the
correlator that plays a crucial role in computations of the power
spectrum.Comment: 19 pages, 5 table
General plane wave mode functions for scalar-driven cosmology
We give a solution for plane wave scalar, vector and tensor mode functions in
the presence of any homogeneous, isotropic and spatially flat cosmology which
is driven by a single, minimally coupled scalar. The solution is obtained by
rescaling the various mode functions so that they reduce, with a suitable scale
factor and a suitable time variable, to those of a massless, minimally coupled
scalar. We then express the general solution in terms of co-moving time and the
original scale factor.Comment: 6 pages, revtex4, no figures, revised version corrects an
embarrassing mistake (in the published version) for the parameter q_C.
Affected eqns are 45 and 6
Two Loop Scalar Bilinears for Inflationary SQED
We evaluate the one and two loop contributions to the expectation values of
two coincident and gauge invariant scalar bilinears in the theory of massless,
minimally coupled scalar quantum electrodynamics on a locally de Sitter
background. One of these bilinears is the product of two covariantly
differentiated scalars, the other is the product of two undifferentiated
scalars. The computations are done using dimensional regularization and the
Schwinger-Keldysh formalism. Our results are in perfect agreement with the
stochastic predictions at this order.Comment: 43 pages, LaTeX 2epsilon, 5 figures (using axodraw.sty) Version 2 has
updated references and important corrections to Tables 3-5 and to eqns
(139-141), (145-146), (153-155), (158) and (160
The Coincidence Limit of the Graviton Propagator in de Donder Gauge on de Sitter Background
We explicitly work out the de Sitter breaking contributions to the recent
solution for the de Donder gauge graviton propagator on de Sitter. We also
provide explicit power series expansions for the two structure functions, which
are suitable for implementing dimensional regularization. And we evaluate the
coincidence limit of the propagator.Comment: 41 pages, uses LaTeX 2e, version 2 has some typoes correcte
A new tape product for optical data storage
A new tape product has been developed for optical data storage. Laser data recording is based on hole or pit formation in a low melting metallic alloy system. The media structure, sputter deposition process, and media characteristics, including write sensitivity, error rates, wear resistance, and archival storage are discussed
Solving the Effective Field Equations for the Newtonian Potential
Loop corrections to the gravitational potential are usually inferred from
scattering amplitudes, which seems quite different from how the linearized
Einstein equations are solved with a static, point mass to give the classical
potential. In this study we show how the Schwinger-Keldysh effective field
equations can be used to compute loop corrections to the potential in a way
which parallels the classical treatment. We derive explicit results for the one
loop correction from the graviton self-energy induced by a massless, minimally
coupled scalar.Comment: 15 pages, uses LaTeX2
Plane waves in a general Robertson-Walker background
We present an exact solution for the plane wave mode functions of a massless,
minimally coupled scalar propagating in an arbitrary homogeneous, isotropic and
spatially flat geometry. Our solution encompasses all previous solvable special
cases such as de Sitter and power law expansion. Moreover, it can generate the
mode functions for gravitons. We discuss some of the many applications that are
now possible.Comment: 11 pages, revtex4, no figures, version 3 is vastly expanded (from 57
eqns to 166) to give an explicit expression for the transfer matrix, and to
expand it in the ultraviolet and the infrared. We use the infrared limit to
give an improved result for the gravitational wave contribution to CMB
anisotropie
Magnetic Field Response Measurement Acquisition System
This paper presents a measurement acquisition method that alleviates many shortcomings of traditional measurement systems. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. Wire degradation has resulted in aircraft fatalities and critical space launches being delayed. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. Power is wirelessly provided to the sensing element by using Faraday induction. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response frequency, resistance and amplitude has been developed and is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. The method does not require the sensors to be near the acquisition hardware. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed. Examples of magnetic field response sensors and the respective measurement characterizations are presented. Implementation of this method on an aerospace system is discussed
Thin-Film Magnetic-Field-Response Fluid-Level Sensor for Non-Viscous Fluids
An innovative method has been developed for acquiring fluid-level measurements. This method eliminates the need for the fluid-level sensor to have a physical connection to a power source or to data acquisition equipment. The complete system consists of a lightweight, thin-film magnetic-field-response fluid-level sensor (see Figure 1) and a magnetic field response recorder that was described in Magnetic-Field-Response Measurement-Acquisition System (LAR-16908-1), NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. The sensor circuit is a capacitor connected to an inductor. The response recorder powers the sensor using a series of oscillating magnetic fields. Once electrically active, the sensor responds with its own harmonic magnetic field. The sensor will oscillate at its resonant electrical frequency, which is dependent upon the capacitance and inductance values of the circuit
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