2,497 research outputs found

    Scalar Perturbations in Scalar Field Quantum Cosmology

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    In this paper it is shown how to obtain the simplest equations for the Mukhanov-Sasaki variables describing quantum linear scalar perturbations in the case of scalar fields without potential term. This was done through the implementation of canonical transformations at the classical level, and unitary transformations at the quantum level, without ever using any classical background equation, and it completes the simplification initiated in investigations by Langlois \cite{langlois}, and Pinho and Pinto-Neto \cite{emanuel2} for this case. These equations were then used to calculate the spectrum index nsn_s of quantum scalar perturbations of a non-singular inflationary quantum background model, which starts at infinity past from flat space-time with Planckian size spacelike hypersurfaces, and inflates due to a quantum cosmological effect, until it makes an analytical graceful exit from this inflationary epoch to a decelerated classical stiff matter expansion phase. The result is ns=3n_s=3, incompatible with observations.Comment: 10 pages, 2 figures, accepted version to Physical Review D 7

    Electronic control/display interface technology

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    An effort to produce a representative workstation for the Space Station Data Management Test Bed that provides man/machine interface design options for consolidating, automating, and integrating the space station work station, and hardware/software technology demonstrations of space station applications is discussed. The workstation will emphasize the technologies of advanced graphics engines, advanced display/control medias, image management techniques, multifunction controls, and video disk utilizations

    A Structural Break Approach to Analysing the Impact of the QE Portfolio Balance Channel on the US Stock Market

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    Following the 1929 Wall Street collapse, the initial response to the institutional failures and collapsing financial system was to allow the markets to self-correct, which led to a significant period of economic depression. In contrast the US (and UK) governments responded to the 2008 financial crisis with extra liquidity for the banking sector and a stimulus package, but why was there such a different response? Following a light touch approach to Bear Stearns and Lehmann’s, it became clear that without greater intervention, the effect would become contagious throughout the financial system. One of the most important forms of intervention was Quantitative Easing (QE) and historically low interest rates. This study finds that QE substantially reduced the Equity Risk Premium on S&P equities through a 9.6% rise in prices, thus reducing returns. Consequentially, this drives portfolios to seek risker asset classes to make up for the shortfall in returns. This suggests that the combination of low interest rates and QE, when compared to expansion alone, has had a marked change on equity prices and ERP. Furthermore, there is evidence that regime shifts support these findings. Such unforeseen consequences in the equity markets is of great interest to policy makers when deciding on a response to such exceptional circumstances, and researchers investigating monetary policy responses to the next inevitable extreme financial crisis

    Composition profiles of InAs–GaAs quantum dots determined by medium-energy ion scattering

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    The composition profile along the [001] growth direction of low-growth-rate InAs–GaAs quantum dots (QDs) has been determined using medium-energy ion scattering (MEIS). A linear profile of In concentration from 100% In at the top of the QDs to 20% at their base provides the best fit to MEIS energy spectra

    A Study of Radiative Muon Pair Production at the Z0Z^{0} Resonance

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    Book Reviews

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    Book Reviews

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    Gauge Fields in the Functional Schrodinger Representation

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    We explore gauge fields in the functional Schrödinger representation. We first consider perturbatively solving quantum electrodynamics using known free field wave functionals. Failures of ordinary perturbative techniques force us to develop techniques to solve nontrivial functional differential equations. These techniques can also be used for Yang-Mills as we also demonstrate. We regularize QED in a new fashion using functional directional derivatives. This may also be generalized to Yang-Mills. We carry out mass renormalization in QED using wave functionals since no one has explicitly done it before. We briefly look at magnetic flux tubes in the Abelian Higgs model to illustrate renormalization in a variational calculation. We also perform a variational calculation using wave functionals in Yang-Mills to see if quantum fluctuations can produce electric flux tubes.</p
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