The Challenges of El Salvador?s Conditional Cash Transfer Programme, Red Solidaria

In the context of the increasing prominence of conditional cash transfers (CCTs) in the development agenda of many developing countries, this Country Study provides an analytic overview of the challenges faced by El Salvador?s CCT programme, Red Solidaria, (Solidarity Network). The purpose is to generate an information base for comparative studies on the prospects and potential difficulties of implementing CCTs in country settings different from those of the pioneer programmes, such as in Brazil and Mexico. The study describes Red Solidaria´s origins and components and discusses major aspects of its design and implementation. A particular emphasis is placed on the programme?s co-responsibilities, exit rules and targeting strategy. The study also covers the topics of institutional structures, intersectoral coordination and political support for such programmes. The conclusion is that Red Solidaria is an informative example of how a small country with limited resources can successfully set up a complex CCT programme. Still, the study notes that there are pending issues and remaining challenges for the programme. These relate, in particular, to strengthening mechanisms of local participation; coordinating the CCTs with other dimensions of Red Solidaria, such as productive projects; lengthening the duration of benefits for meeting human-capital objectives; clarifying eligibility requirements and how changes in family conditions can affect such requirements; and distinguishing conditionalities from ordinary programme co-responsibilities. An issue of overriding importance is to develop a broader long-term social protection strategy for El Salvador, with which CCTs would be integrated instead of being regarded as a stand-along programme.El Salvador; Conditional Cash Transfer Programme; CCT, Red Solidaria

Exploiting Twistor Techniques for One-loop QCD Amplitudes

In this talk we describe the recursive Approach to One-loop QCD Matrix Elements.Comment: Talk presented by David C. Dunbar at Loop and Legs 2006, 5 page

D-dimensional unitarity cut method

We develop a unitarity method to compute one-loop amplitudes with massless propagators in d=4-2*epsilon dimensions. We compute double cuts of the loop amplitudes via a decomposition into a four-dimensional and a -2*epsilon-dimensional integration. The four-dimensional integration is performed using spinor integration or other efficient techniques. The remaining integral in -2*epsilon dimensions is cast in terms of bubble, triangle, box, and pentagon master integrals using dimensional shift identities. The method yields results valid for arbitrary values of epsilon.Comment: 4 pages. v2: references change

On-shell recursion for massive fermion currents

We analyze the validity of BCFW recursion relations for currents of n - 2 gluons and two massive quarks, where one of the quarks is off shell and the remaining particles are on shell. These currents are gauge-dependent and can be used as ingredients in the unitarity-based approach to computing one-loop amplitudes. The validity of BCFW recursion relations is well known to depend on the so-called boundary behavior of the currents as the momentum shift parameter goes to infinity. With off-shell currents, a new potential problem arises, namely unphysical poles that depend on the choice of gauge. We identify conditions under which boundary terms are absent and unphysical poles are avoided, so that there is a natural recursion relation. In particular, we are able to choose a gauge in which we construct a valid shift for currents with at least n - 3 gluons of the same helicity. We derive an analytic formula in the case where all gluons have the same helicity. As by-products, we prove the vanishing boundary behavior of general off-shell objects in Feynman gauge, and we find a compact generalization of Berends-Giele gluon currents with a generic reference spinor.Comment: 30 pages, 8 figures; v2 minor corrections, journal versio

On Triple-Cut of Scattering Amplitudes

It is analysed the triple-cut of one-loop amplitudes in dimensional regularisation within spinor-helicity representation. The triple-cut is defined as a difference of two double-cuts with the same particle content, and a same propagator carrying, respectively, causal and anti-causal prescription in each of the two cuts. That turns out into an effective tool for extracting the coefficients of the three-point functions (and higher-point ones) from one-loop-amplitudes. The phase-space integration is oversimplified by using residues theorem to perform the integration over the spinor variables, via the holomorphic anomaly, and a trivial integration on the Feynman parameter. The results are valid for arbitrary values of dimensions.Comment: 17 pages, 8 figure

External leg corrections in the unitarity method

Unitarity cuts diverge in the channel of a single massive external fermion. We propose an off-shell continuation of the momentum that allows a finite evaluation of the unitarity cuts. If the cut is taken with complete amplitudes on each side, our continuation and expansion around the on-shell configuration produces the finite contribution to the bubble coefficient. Finite parts in the expansion of the external leg counterterms must be included explicitly as well.Comment: 28 pages, 9 figures. Published version. Eq. (B.17) corrected, minor clarifications, typos fixe

Recursive Approach to One-loop QCD Matrix Elements

We describe the recursive Approach to One-loop QCD Matrix Elements.Comment: 6 pages, to appear in the proceedings of the 7th International Symposium on Radiative Corrections: Application of Quantum Field Theory to Phenomenology (RADCOR 2005), Japan, 2-7 Oct 200