3,151 research outputs found
The Yang-Mills vacuum in Coulomb gauge
The Yang-Mills Schr\"odinger equation is solved in Coulomb gauge for the
vacuum by the variational principle using an ansatz for the wave functional,
which is strongly peaked at the Gribov horizon. We find an infrared suppressed
gluon propagator, an infrared singular ghost propagator and an almost linearly
rising confinement potential. Using these solutions we calculate the electric
field of static color charge distributions relevant for mesons and baryons.Comment: 4 pages, 5 figures, Proceedings ``Confinement Conference Sardinia
2004'
RF-dressed Rydberg atoms in hollow-core fibres
The giant electro-optical response of Rydberg atoms manifests itself in the
emergence of sidebands in the Rydberg excitation spectrum if the atom is
exposed to a radio-frequency (RF) electric field. Here we report on the study
of RF-dressed Rydberg atoms inside hollow-core photonic crystal fibres
(HC-PCF), a system that enables the use of low modulation voltages and offers
the prospect of miniaturised vapour-based electro-optical devices. Narrow
spectroscopic features caused by the RF field are observed for modulation
frequencies up to 500 MHz.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the Institute of Physics
Heat-kernel expansion and counterterms of the Faddeev-Popov determinant in Coulomb and Landau gauge
The Faddeev-Popov determinant of Landau gauge in d dimensions and Coulomb
gauge in d+1 dimensions is calculated in the heat-kernel expansion up to
next-to-leading order. The UV-divergent parts in d=3,4 are isolated and the
counterterms required for a non-perturbative treatment of the Faddeev-Popov
determinant are determined.Comment: 7 page
Economics of education research: a review and future prospects
In this paper we offer an appraisal of the economics of education research area, charting its history as a field and discussing the ways in which economists have contributed both to education research and to education policy-making. In particular, we highlight the theoretical and methodological contributions that economists have made to the field of education during the last 50 years. Despite the success of the economics of education as a field of inquiry, we argue that some of the contributions made by economists could be limited if the economics of education is seen as quite distinct from the other disciplines working in the field of education. In these areas of common interest, economists need to work side by side with the other major disciplines in the field of education if their contribution to the field is to be maximised, particularly in terms of applying improved methodology. We conclude that the study of education acquisition and its economic and social impact in the economics of education research area is very likely to remain a fertile research ground. Acknowledgement
Dataset of coded handwriting features for use in statistical modelling
© 2017 The Authors The data presented here is related to the article titled, âUsing handwriting to infer a writer's country of origin for forensic intelligence purposesâ (Agius et al., 2017) [1]. This article reports original writer, spatial and construction characteristic data for thirty-seven English Australian1 writers and thirty-seven Vietnamese writers. All of these characteristics were coded and recorded in Microsoft Excel 2013 (version 15.31). The construction characteristics coded were only extracted from seven characters, which were: âgâ âhâ âthâ âMâ â0â â7â and â9â. The coded format of the writer, spatial and construction characteristics is made available in this Data in Brief in order to allow others to perform statistical analyses and modelling to investigate whether there is a relationship between the handwriting features and the nationality of the writer, and whether the two nationalities can be differentiated. Furthermore, to employ mathematical techniques that are capable of characterising the extracted features from each participant
Truncating first-order Dyson-Schwinger equations in Coulomb-Gauge Yang-Mills theory
The non-perturbative domain of QCD contains confinement, chiral symmetry
breaking, and the bound state spectrum. For the calculation of the latter, the
Coulomb gauge is particularly well-suited. Access to these non-perturbative
properties should be possible by means of the Green's functions. However,
Coulomb gauge is also very involved, and thus hard to tackle. We introduce a
novel BRST-type operator r, and show that the left-hand side of Gauss' law is
r-exact.
We investigate a possible truncation scheme of the Dyson-Schwinger equations
in first-order formalism for the propagators based on an instantaneous
approximation. We demonstrate that this is insufficient to obtain solutions
with the expected property of a linear-rising Coulomb potential. We also show
systematically that a class of possible vertex dressings does not change this
result.Comment: 22 pages, 4 figures, 1 tabl
Brane Induced Gravity, its Ghost and the Cosmological Constant Problem
"Brane Induced Gravity" is regarded as a promising framework for addressing
the cosmological constant problem, but it also suffers from a ghost instability
for parameter values that make it phenomenologically viable. We carry out a
detailed analysis of codimension > 2 models employing gauge invariant variables
in a flat background approximation. It is argued that using instead a curved
background sourced by the brane would not resolve the ghost issue, unless a
very specific condition is satisfied (if satisfiable at all). As for other
properties of the model, from an explicit analysis of the 4-dimensional
graviton propagator we extract a mass, a decay width and a momentum dependent
modification of the gravitational coupling for the spin 2 mode. In the flat
space approximation, the mass of the problematic spin 0 ghost is instrumental
in filtering out a brane cosmological constant. The mass replaces a background
curvature that would have had the same function. The optical theorem is used to
demonstrate the suppression of graviton leakage into the uncompactified bulk.
Then, we derive the 4-dimensional effective action for gravity and show that
general covariance is spontaneously broken by the bulk-brane setup. This
provides a natural realization of the gravitational Higgs mechanism. We also
show that the addition of extrinsic curvature dependent terms has no bearing on
linearized brane gravity.Comment: v2: LaTeX, JHEP style, 41 pages, 3 eps figures. Partly rewritten to
improve presentation, results unchanged, published versio
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