N=2 SYM Action as a BRST Exact Term, Topological Yang Mills and Instantons

By constructing a nilpotent extended BRST operator \bs that involves the N=2 global supersymmetry transformations of one chirality, we show that the standard N=2 off-shell Super Yang Mills Action can be represented as an exact BRST term \bs \Psi, if the gauge fermion $\Psi$ is allowed to depend on the inverse powers of supersymmetry ghosts. By using this nonanalytical structure of the gauge fermion (via inverse powers of supersymmetry ghosts), we give field redefinitions in terms of composite fields of supersymmetry ghosts and N=2 fields and we show that Witten's topological Yang Mills theory can be obtained from the ordinary Euclidean N=2 Super Yang Mills theory directly by using such field redefinitions. In other words, TYM theory is obtained as a change of variables (without twisting). As a consequence it is found that physical and topological interpretations of N=2 SYM are intertwined together due to the requirement of analyticity of global SUSY ghosts. Moreover, when after an instanton inspired truncation of the model is used, we show that the given field redefinitions yield the Baulieu-Singer formulation of Topological Yang Mills.Comment: Latex, 1+15 pages. Published versio

Noncommutative gravity coupled to fermions: second order expansion via Seiberg-Witten map

We use the Seiberg-Witten map (SW map) to expand noncommutative gravity coupled to fermions in terms of ordinary commuting fields. The action is invariant under general coordinate transformations and local Lorentz rotations, and has the same degrees of freedom as the commutative gravity action. The expansion is given up to second order in the noncommutativity parameter {\theta}. A geometric reformulation and generalization of the SW map is presented that applies to any abelian twist. Compatibility of the map with hermiticity and charge conjugation conditions is proven. The action is shown to be real and invariant under charge conjugation at all orders in {\theta}. This implies the bosonic part of the action to be even in {\theta}, while the fermionic part is even in {\theta} for Majorana fermions.Comment: 27 pages, LaTeX. Revised version with proof of charge conjugation symmetry of the NC action and its parity under theta --> - theta (see new sect. 2.6, sect. 6 and app. B). References added. arXiv admin note: substantial text overlap with arXiv:0902.381

Using Administrative Data to Count and Classify Households with Local Applications

Households rather than individuals are being increasingly used for research and to target and evaluate public policy. As a result accurate and timely household level statistics have become an increasing necessity especially at local level. However, official sources of information on households are fragmented with significant gaps and inaccuracies that limit their usefulness. This paper reviews present statistical arrangements and then describes a new approach to data collection and household classification which combine various local administrative sources. An intermediate step is the creation of local population counts which are converted into household types and these methods are described in two companion papers previously published in this journal. The utility and advantages of the approach are demonstrated using the example of the six Olympic London Boroughs for whom the data collection was undertaken in 2011 and the analysis subsequently

A hybrid light source with integrated inorganic light-emitting diode and organic polymer distributed feedback grating

We report a compact light source that incorporates a semiconductor light-emitting diode, nanostructured distributed feedback (DFB) Bragg grating and spin-coated thin conjugated polymer film. With this hybrid structure, we transferred electrically generated 390 nm ultraviolet light to an organic polymer via optical pumping and out-couple green luminescence to air through a second-order DFB grating. We demonstrate the feasibility of electrically driven, hybrid, compact light-emitting devices and lasers in the visible range. © IOP Publishing Ltd