51,462 research outputs found

    The topological susceptibility in `full' (UK)QCD

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    We report first calculations of the topological susceptibility measured using the field theoretic method on SU(3) gauge configurations produced by the UKQCD collaboration with two flavours of dynamical, improved, Wilson fermions. Using three ensembles with matched lattice spacing but differing sea quark mass we find that hybrid Monte Carlo simulation appears to explore the topological sectors efficiently, and a topological susceptibility consistent with increasing linearly with the quark mass.Comment: LaTeX. 4 PostScript figures. Contribution to LATTICE99(topology

    Magnetic monopole clusters, and monopole dominance after smoothing in the maximally Abelian gauge of SU(2)

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    In the maximally Abelian gauge of SU(2), the clusters of monopole current are found to divide into two distinct classes. The largest cluster permeates the lattice, has a density that scales and produces the string tension. The remaining clusters possess an approximate 1/l^3 number density distribution (l is the cluster length), their radii vary as \sqrt l and their total current density does not scale. Their contribution to the string tension is compatible with being exactly zero. Their number density can be thought of as arising from an underlying scale invariant distribution. This suggests that they are not related to instantons. We also observe that when we locally smoothen the SU(2) fields by cooling, the string tension due to monopoles becomes much smaller than the SU(2) string tension. This dramatic loss of Abelian/monopole dominance occurs even after just one cooling step.Comment: Talk presented at LATTICE97(topology). LaTeX, with 4 PS figure

    Instantons and Monopoles in the Maximally Abelian Gauge

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    We study the Abelian projection of SU(2) instantons in the Maximally Abelian gauge. We find that in this gauge an isolated instanton produces a closed monopole loop within its core and the size of this loop increases with the core size. We show that this result is robust against the introduction of small quantum fluctuations. We investigate the effects of neighbouring (anti)instantons upon each other and show how overlapping (anti)instantons can generate larger monopole loops. We find, however, that in fields that are typical of the fully quantised vacuum only some of the large monopole loops that are important for confinement have a topological origin. We comment on what this may imply for the role of instantons in confinement and chiral symmetry breaking.Comment: 14 pages LaTeX plus 5 PostScript figures. Uses epsf.sty. Self-unpacking, uuencoded tar-compressed fil

    Workers Made Idle by Company Strikes and the 'British Disease'

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    The strikes' literature is dominated by the causes and effects of strike action as they relate directly to strikers themselves. This paper considers another important group of affected workers – those individuals incidentally made idle as a result of the strike action of others. Using a unique data set of the British Engineering Employers' Federation (EEF), it examines the years 1960 to 1970, a critical period in Britain's postwar strikes’ history. The mid-point of this decade marked the start of the era of the 'British Disease', a universally adopted title given to Britain's perceived international leadership in strikes incidence and industrial unrest. Workers made idle were an important symptom of the disease. In the study here, they accounted for 72% of days lost in disputes in which they were involved and 44% of total days lost in all disputes. Consideration is given to the likely causes of these incidental layoffs within 7130 strikes of EEF federated firms covering engineering, automotive and metal industries. Particular attention is given to the British car industry, accounting for 22% of total EEF strikes during the period of study. The regression analysis examines the causes of workers being made idle with explanatory variables covering labour market conditions, strikes durations, pay issues, non-pay issues. The regressions also control for company, union, geographical districts, annual and seasonal fixed effects.strikes, workers made idle, pay disputes, non-pay disputes

    A computationally efficient multi-mode equaliser based on reconfigurable frequency domain processing

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    The relation between cholesterol and haemorrhagic or ischaemic stroke in the Renfrew/Paisley study

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    Studies have found little association between cholesterol and overall stroke risk, but this could be attributable to different relations for haemorrhagic and ischaemic stroke. Stroke mortality data from prospective studies cannot usually be divided into stroke subtypes. We have therefore analysed stroke based on hospital admissions, obtained by computerised linkage with acute hospital discharges in Scotland for a large prospective cohort study

    Monopole Spectra in non-Abelian Gauge Theories

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    We study the continuum limit of the length spectrum of magnetic monopole structures found after various Abelian projections of pure gauge SU(2), including the maximally Abelian gauge. We comment on Gribov copies, and measurements of the string tension.Comment: Talk presented at LATTICE96(topology) LaTeX, with 4 LaTeX figure

    Monopole clusters in Abelian projected gauge theories

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    We show that the monopole currents which one obtains in the maximally Abelian gauge of SU(2) fall into two quite distinct classes (when the volume is large enough). In each field configuration there is precisely one cluster that permeates the whole lattice volume. It has a current density and a magnetic screening mass that scale and it produces the whole of the string tension. The remaining clusters have a number density that follows an approximate power law proportional to the inverse cube of l where l is the length of the monopole world line in lattice units. These clusters are localised in space-time with radii which vary as the square root of l. In terms of the radius r these `lumps' have a scale-invariant distribution proportional to (dr/r . 1/{r^4}). Moreover they appear not to contribute at all to the string tension. The fact that they are scale-invariant at small distances would seem to rule out an instanton origin.Comment: LaTeX, 31 pages, 11 PostScript figures. Typo in Table 2 correcte
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