New relations between spinor and scalar one-loop effective Lagrangians in constant background fields

Simple new relations are presented between the one-loop effective Lagrangians of spinor and scalar particles in constant curvature background fields, both electromagentic and gravitational. These relations go beyond the well-known cases for self-dual background fields

A Multicommodity EU Policy Framework Incorporating Public Good Criteria into the Direct Payment System in Agriculture

For decades the CAP has been the major influence in shaping EU agriculture and food production. The economic and policy environment in the EU is now very different from that which prevailed in the earlier decades. The future economic, social and geographic diversity of the EU will be further increased by enlargement. Agricultural policies and the related operational frameworks will inevitably change to accommodate this added diversity and the changing societal and consumer values. This paper evaluates how the current shape of EU agriculture has been influenced by the reforms to date. It also attempts to focus on where EU farming may be, or wish to go, over the next decade. The evaluation is restricted to the beef sector as it has been to the forefront in the policy reforms of the last decade and because the adjustments were inevitably complex due to the scale of the oversupply problems, the biological and market intricacies involved. This evaluation concluded that the current EU beef policy is severely constrained with poor targeting of the income supports, high production costs, based on an administratively complex and expensive control system without any clear benefit to either society or taxpayer for a rather large expenditure. In the past, agricultural policy in the EU was primarily driven by the need for a secure food supply and with the objective of sustaining the economic and social needs of farmers. But, in the well fed and affluent EU society of the 21st century, agricultural policy will be mainly driven by the economic and social goals which are rapidly changing. This society places a declining value on extra units of food production, but an increasing value on any public goods consumed in the production process. As a consequence, the mix of agricultural production and public goods that this society is prepared to support financially is changing rapidly. The level and components of farm incomes in the EU in the 21st century will reflect these changes. Farm revenue will likely consist of a mix of payments for conventional agricultural products and public goods. The public good payments will be conditional on the level and type of inputs used, farming practices, types of products produced and a societal vision of the role of farming. This will affect production costs, scale of operation and the future configuration of agriculture and rural society. To meet this evolving situation the paper also develops and outlines a multicommodity framework by which the EU could reorient its direct payment (DP) system to incorporate a range of public good values to the mutual benefit of consumers, taxpayers and farmers.CAP reform, direct payments for public goods, animal welfare, environment, food safety, production methods, extensive production, economic, social and geographic diversity, future role of farming, an administrative framework., Agricultural Finance,

The Complexity of Repairing, Adjusting, and Aggregating of Extensions in Abstract Argumentation

We study the computational complexity of problems that arise in abstract argumentation in the context of dynamic argumentation, minimal change, and aggregation. In particular, we consider the following problems where always an argumentation framework F and a small positive integer k are given. - The Repair problem asks whether a given set of arguments can be modified into an extension by at most k elementary changes (i.e., the extension is of distance k from the given set). - The Adjust problem asks whether a given extension can be modified by at most k elementary changes into an extension that contains a specified argument. - The Center problem asks whether, given two extensions of distance k, whether there is a "center" extension that is a distance at most (k-1) from both given extensions. We study these problems in the framework of parameterized complexity, and take the distance k as the parameter. Our results covers several different semantics, including admissible, complete, preferred, semi-stable and stable semantics

Quantum Group Covariance and the Braided Structure of Deformed Oscillators

The connection between braided Hopf algebra structure and the quantum group covariance of deformed oscillators is constructed explicitly. In this context we provide deformations of the Hopf algebra of functions on SU(1,1). Quantum subgroups and their representations are also discussed.Comment: 12 pages, to be published in JM

"Background Field Integration-by-Parts" and the Connection Between One-Loop and Two-Loop Heisenberg-Euler Effective Actions

We develop integration-by-parts rules for Feynman diagrams involving massive scalar propagators in a constant background electromagnetic field, and use these to show that there is a simple diagrammatic interpretation of mass renormalization in the two-loop scalar QED Heisenberg-Euler effective action for a general constant background field. This explains why the square of a one-loop term appears in the renormalized two-loop Heisenberg-Euler effective action. No integrals need be evaluated, and the explicit form of the background field propagators is not needed. This dramatically simplifies the computation of the renormalized two-loop effective action for scalar QED, and generalizes a previous result obtained for self-dual background fields.Comment: 13 pages; uses axodraw.st

Braided Oscillators

The braided Hopf algebra structure of the generalized oscillator is investigated. Using the solutions two types of braided Fibonacci oscillators are introduced. This leads to two types of braided Biedenharn-Macfarlane oscillators.Comment: 12 pages, latex, some references added, published versio

A Gauge-Gravity Relation in the One-loop Effective Action

We identify an unusual new gauge-gravity relation: the one-loop effective action for a massive spinor in 2n dimensional AdS space is expressed in terms of precisely the same function [a certain multiple gamma function] as the one-loop effective action for a massive charged scalar in 4n dimensions in a maximally symmetric background electromagnetic field [one for which the eigenvalues of F_{\mu\nu} are maximally degenerate, corresponding in 4 dimensions to a self-dual field, equivalently to a field of definite helicity], subject to the identification F^2 \Lambda, where \Lambda is the gravitational curvature. Since these effective actions generate the low energy limit of all one-loop multi-leg graviton or gauge amplitudes, this implies a nontrivial gauge-gravity relation at the non-perturbative level and at the amplitude level.Comment: 6 page