An improved AFS phase for AdS3 string integrability

We propose a number of modifications to the classical term in the dressing phase for integrable strings in AdS3 x S3 x S3 x S1, and check these against existing perturbative calculations, crossing symmetry, and the semiclassical limit of the Bethe equations. The principal change is that the phase for different masses should start with a term Q_1 Q_2, like the one-loop AdS3 dressing phase, rather than Q_2 Q_3 as for the original AdS5 AFS phase.Comment: 7 page

Massless L\"uscher Terms and the Limitations of the AdS3 Asymptotic Bethe Ansatz

In AdS5/CFT4 integrability the Bethe ansatz gives the spectrum of long strings, accurate up to exponentially small corrections. This is no longer true in AdS3, as we demonstrate here by studying Luscher F-terms with a massless particle running in the loop. We apply this to the classic test of Hernandez & Lopez, in which the su(2) sector Bethe equations (including one-loop dressing phase) should match the semiclassical string theory result for a circular spinning string. These calculations did not agree in AdS3xS3xT4, and we show that the sum of all massless Luscher F-terms can reproduce the difference.Comment: 15 pages, 1 figure; v2:references, typos and clarification

Quantum Strings and the AdS4/CFT3 Interpolating Function

The existence of a nontrivial interpolating function h(\lambda) is one of the novel features of the new AdS4/CFT3 correspondence involving ABJM theory. At strong coupling, most of the investigation of semiclassical effects so far has been for strings in the AdS4 sector. Several cutoff prescriptions have been proposed, leading to different predictions for the constant term in the expansion h(\lambda)=\sqrt{\lambda/2} + c + ... . We calculate quantum corrections for giant magnons, using the algebraic curve, and show by comparing to the dispersion relation that the same prescriptions lead to the same values of c in this CP3 sector. We then turn to finite-J effects, where a comparison with the Luescher F-term correction shows a mismatch for one of the three sum prescriptions. We also compute some dyonic and higher F-terms for future comparisons.Comment: 30 pages, 1 figure, 1 table. v2 has minor improvements to the text, and extra references. v3 has further textual changes, version to appear in JHE

Market Power and Structural Adjustment: The Case of West African Cocoa Market Liberalization

Liberalization of the cocoa market in West Africa, due to structural adjustment reforms, has resulted in the elimination of para-statal marketing boards and initiated the creation of new institutions to replace the marketing services of those agencies. Concerns have been raised as to the effects of these reforms on prices of cocoa received by farmers, welfare measures and competitiveness of marketing channels. Of particular importance is backward integration of multinational processing firms, who take over exporting activities and may collect rents previously captured as export taxes. This paper uses a conjectural variations approach to estimate the degree of market power present in the post-liberalized cocoa bean markets of Ivory Coast and Nigeria. Evidence of market power is found in the Ivory Coast markets between the farmgate and U.S./EU15 imports. The market power, exercised by multinational exporter/processors, must be considered in concert with the Ivorian government who is still collecting export taxes. In contrast, no evidence of market power is found in the Nigerian markets or domestic (farmer to trader) markets of Ivory Coast.Marketing,

Meromorphic Functions and the Topology of Giant Gravitons

Using Mikhailov's map from holomorphic functions to supersymmetric D3-brane solutions, we show how to construct giant gravitons in AdS5 x S5 with toroidal topologies. In the 1/4-BPS sector we show that these are always of the form #^K (S2 x S1), and in the limit in which this becomes a set of m+n perpendicular spherical giants re-connected near to their intersections, we find K in terms of m,n. In the 1/8-BPS sector we find a similar class of solutions.Comment: 10 pages, 8 figure