Three dimensional field theories from infinite dimensional lie algebras

A procedure for constructing topological actions from centrally extended Lie groups is introduced. For a \km\ group, this produces \3al \cs, while for the \vir\ group the result is a new \3al \tft\ whose physical states satisfy the \vir\ \wi. This \tft\ is shown to be a first order formulation of two dimensional induced gravity in the chiral gauge. The extension to $W_3$-gravity is discussed.Comment: 11 pages, USC-92/01

Prospects for New Physics in CP Violation and Rare Decays at LHCb

LHCb is the heavy flavour precision experiment of the proton-proton Large Hadron Collider (LHC) at CERN. It will search for new physics in CP violation and rare decays and is ready for the start-up of the LHC. An overview of its physics program will be given, illustrated by few key examples: measurements of the CKM angle $\gamma$, of the CP violating phase in $B_s \overline{B_s}$ oscillations and searches for new physics in $B^0_d \to K^*\mu^+\mu^-$ and in $B^0_s \to \mu^+\mu^-$.Comment: PANIC08 conference proceedings, 3 page

A classical N=4 super W_3 algebra

I construct classical superextensions of the Virasoro algebra by employing the Ward identities of a linearly realized subalgebra. For the $N=4$ superconformal algebra, this subalgebra is generated by the $N=2$ $U(1)$ supercurrent and a spin~0 $N=2$ superfield. I show that this structure can be extended to an $N=4$ super $W_3$ algebra, and give the complete form of this algebra.Comment: 15 pages, USC/92-02

Livelihood features of small scale fishing communities : A case from Singkarak Lake, west Sumatra Indonesia

While millions of poor still depend on small scale freshwater fisheries to earn a meager leaving, the sector shows overall decline in catches over recent years throughout South East Asia. Among few other causes, overfishing is often pointed out as a main issue. Little research is done regarding the socio-economic and technical diversity among the fishing communities, being both the victims of the problem and its possible cause. This research aims to characterize fishing communities in Singkarak Lake (West Sumatra, Indonesia) by exploring their socio-economic and fishing characteristics and also identifying the problems, constraints confronted by those communities as the entry point for policy formulation in an effort to support small-scale fishermen and to address fisheries related problem appropriately. Results show that fishing communities in Singkarak Lake have high level of homogeneity in terms of their fishing activities which represents the highest in cash households' income, but extreme diversity in portfolio of livelihood activities. Combination of fishing and farming widely practiced by fishers in addition to other income supplements either seasonal or permanent. Income generating activities employed by the fishers become more diverse in conjunction to the decrease of fish production and some other factors such as degraded environmental condition, construction of Hydro Electric Power Plant (HEPP) and fishing practiced itself. Fishing labor productivity is found to be lower than construction works and nearly same as farming labor productivity. However, fishers keep fishing because it can secure their daily food needs. The choice of diversification strategies is also based on the assets owned by the households and on higher labor productivity offered by alternative activities out of fishing. (Résumé d'auteur

Computational Particle Physics for Event Generators and Data Analysis

High-energy physics data analysis relies heavily on the comparison between experimental and simulated data as stressed lately by the Higgs search at LHC and the recent identification of a Higgs-like new boson. The first link in the full simulation chain is the event generation both for background and for expected signals. Nowadays event generators are based on the automatic computation of matrix element or amplitude for each process of interest. Moreover, recent analysis techniques based on the matrix element likelihood method assign probabilities for every event to belong to any of a given set of possible processes. This method originally used for the top mass measurement, although computing intensive, has shown its power at LHC to extract the new boson signal from the background. Serving both needs, the automatic calculation of matrix element is therefore more than ever of prime importance for particle physics. Initiated in the eighties, the techniques have matured for the lowest order calculations (tree-level), but become complex and CPU time consuming when higher order calculations involving loop diagrams are necessary like for QCD processes at LHC. New calculation techniques for next-to-leading order (NLO) have surfaced making possible the generation of processes with many final state particles (up to 6). If NLO calculations are in many cases under control, although not yet fully automatic, even higher precision calculations involving processes at 2-loops or more remain a big challenge. After a short introduction to particle physics and to the related theoretical framework, we will review some of the computing techniques that have been developed to make these calculations automatic. The main available packages and some of the most important applications for simulation and data analysis, in particular at LHC will also be summarized.Comment: 19 pages, 11 figures, Proceedings of CCP (Conference on Computational Physics) Oct. 2012, Osaka (Japan) in IOP Journal of Physics: Conference Serie

Can smallholder farmers meet the financial costs of irrigation services? A case study on economic efficiency and social equity in South Africa

Considering water as an economic good consists of, among other requisites, properly assessing the cost incurred by supplying and managing the resource, and the required infrastructure thereof. This paper investigates and assesses the full financial costs of irrigation services in smallholder conditions, and discusses the possible match between farmers' performances and the costs incurred, from a case study in South Africa. The paper first presents the specific conditions and features of smallholder irrigation, with emphasis on South African examples. Several specific issues are identified and discussed, such as the lack of records on infrastructure and initial costs, the multiple purpose and actual uses of certain equipment and infrastructure, the shift in purpose of others over time, the inclusion of certain small, yet indispensable equipment in the calculation, the partial refurbishment works on particular assets, and the lack of a standard basis for calculation under tropical, developing conditions (e.g. on service life, maintenance requirements). Second, after a brief review of current frameworks, concepts and terminology, the paper attempts to evaluate financial costs of irrigation services on a case study in South Africa. The results suggest that the application of existing methodologies proves feasible, provided some adapted data and available information replace the original ones, especially for capital costs. This applies to the discount rate, calculation of the current value, and estimation of the service life of infrastructure and equipment. In particular, several scenarios have been tested in order to estimate a surrogate to the discount rate. The average yield on Negotiable Certificates of Deposit (NCD) is suggested as a surrogate for treasury bills, hence for the discount rate. The case study demonstrates the high costs of irrigation services as compared to the low income derived from irrigation production in smallholder schemes; hence the need for renewed public intervention and subsidization, especially on account of the current context of management transfer, privatization, and liberalization. The case also indicates that under the current production levels and marketing practices, farmers would not be able to achieve the targeted return on assets (ROA) of four percent, as suggested by Government. The paper suggests a shift in underlying policy and societal mindset about water charging system in smallholder irrigation. Cost recovery and water charges should not be considered a further burden or deterring factors for smallholder irrigation, but rather incentives towards increased production and ultimately improved contribution to the country's economy. (Résumé d'auteur