Burglary project

This report outlines the process and findings from an innovative project for students. This work was part of the curriculum and involved students working with West Yorkshire Police as part of the safer Leeds project in designing and making a film for students n crime prevention and personal safety in Leed

How do constituent quarks arise in QCD? Perturbation theory and the infra-red

We motivate the use of dressed charges by arguing that such objects are needed to describe, e.g., constituent quarks and, in general, physical charged states in gauge theories. We give a short introduction to dressings in both QED and QCD. We put special emphasis on the infra-red properties of a moving dressed charge. To be more precise, we demonstrate that the one loop propagator of a relativistic dressed charge can be renormalized in the mass shell scheme with no infra-red divergence showing up.Comment: 5 pages, espcrc2.sty required, talk given at QDC-96, Montpellier, July 1996, A related simulation may be found at http://www.ifae.es/~roy

Asymptotic Dynamics in Quantum Field Theory

A crucial element of scattering theory and the LSZ reduction formula is the assumption that the coupling vanishes at large times. This is known not to hold for the theories of the Standard Model and in general such asymptotic dynamics is not well understood. We give a description of asymptotic dynamics in field theories which incorporates the important features of weak convergence and physical boundary conditions. Applications to theories with three and four point interactions are presented and the results are shown to be completely consistent with the results of perturbation theory.Comment: 18 pages, 3 figure

A New Symmetry for QED

We demonstrate that QED exhibits a previously unobserved symmetry. Some consequences are discussed.Comment: 9 pages, MZ-TH/93-02, DIAS-STP-93-0

Macrofauna do solo em estágios sucessionais de alteração da paisagem na região do distrito da BR-163, oeste do Pará.

A macrofauna do solo apresenta alta diversidade e rápida capacidade de reprodução, sendo considerada excelente bioindicadora, e suas propriedades ou funções indicam e determinam a qualidade ou o nível de degradação do solo..

Coulomb gauge Gribov copies and the confining potential

We study the approach, initiated by Marinari et al., to the static inter-quark potential based on Polyakov lines of finite temporal extent, evaluated in Coulomb gauge. We show that, at small spatial separations, the potential can be understood as being between two separately gauge invariant colour charges. At larger separations Gribov copies obstruct the non-perturbative identification of individually gauge invariant colour states. We demonstrate, for the first time, how gauge invariance can be maintained quite generally by averaging over Gribov copies. This allows us to extend the analysis of the Polyakov lines and the corresponding, gauge invariant quark-antiquark state to all distance scales. Using large scale lattice simulations, we show that this interpolating state possesses a good overlap with the ground state in the quark-antiquark sector and yields the full static inter-quark potential at all distances. A visual representation of the Gribov copies on the lattice is also presented.Comment: 22 pages, 9 figures, v2: minor changes, references adde

Follow up of a cohort of intravenous heroin users in north and south central Dublin and in Dun Laoghaire.

Three studies of intravenous heroin users, in electoral wards in the north and south of central Dublin and in Dun Laoghaire, were undertaken in 1982-84. One hundred and one out of 203 intravenous injectors in these three studies are known to have been tested in Dublin for infection by the Human Immunodeficiency Virus (HIV) and 87 of the 101, or 86% are HIV Positive. Ninety two had also been tested for Hepatitis B infection (Hab) and 76 of the 92 were positive for the hepatitis antigen. The majority of those at present known to be HIV Positive in the Republic of Ireland are, or were, intravenous drug users