Sovereign Debt: Default, Market Sanction, and Bailout

This paper explores the case of a sovereign indebted country facing a choice of economic policy today that will determine the country's ability to continue its debt servicing in the future. If the sovereign undertakes an unsound economic policy it will repudiate its debt with certainty; otherwise it will repudiate its debt with some positive probability. In our framework there is no court to enforce contracts. However, we assume the existence of a multilateral financial institution that could bailout the financially troubled sovereign country. Our focus is on the incentives created by the perspective of a bailout, as well as the punishment that the international financial markets could impose on the defaulting country, on today's economic policy. This essay provides a theoretical grounding for the IMF and other multilateral agencies intervention on the international financial markets showing that, unlike the idea that bailouts create both debtor and creditor moral hazard, it is sometimes a result of creditors' overreaction to the prospect of a liquidity crisis. The main result of the essay is that the multilateral will be better off bailing out the country regardless of the economic policy undertaken in order to avoid bigger losses from a generalized financial crisissovereign debt, default, bailout, creadible threat, market sanction

Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products

Cu-Al layered double hydroxides (LDHs) with Cu/Al ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH)2 and CuCO3 and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 °C), hydrothermally (150 °C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 °C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 °C itself. Reductive decomposition yields a composite of Cu2O and Al(OH)3, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu2O (<1 μm). © 2009 Elsevier Inc. All rights reserved

Synthesis, Structure Refinement and Chromate Sorption Characteristics of an Al-Rich Bayerite-Based Layered Double Hydroxide

“Imbibition” of Zn2+ ions into the cation vacancies of bayerite–Al(OH)3 and NO3- ions into the interlayer gallery yields an Al-rich layered double hydroxide with Al/Zn ratio ~3. NO3- ions are intercalated with their molecular planes inclined at an angle to the plane of the metal hydroxide slab and bonded to it by hydrogen bonds. Rietveld refinement of the structure shows that the monoclinic symmetry of the precursor bayerite is preserved in the product, showing that the imbibition is topochemical in nature. The nitrate ion is labile and is quantitatively replaced by CrO42- ions from solution. The uptake of CrO42- ions follows a Langmuir adsorption isotherm, thus showing that the hydroxide is a candidate material for green chemistry applications for the removal of CrO42- ions from waste water. Rietveld refinement of the structure of the hydroxide after CrO42- inclusion reveals that the CrO42- ion is intercalated with one of its 2-fold axes parallel to the b-crystallographic axis of the crystal, also the principal 2 axis of the monoclinic cell

On-Shell Recursion Relations for Generic Theories

We show that on-shell recursion relations hold for tree amplitudes in generic two derivative theories of multiple particle species and diverse spins. For example, in a gauge theory coupled to scalars and fermions, any amplitude with at least one gluon obeys a recursion relation. In (super)gravity coupled to scalars and fermions, the same holds for any amplitude with at least one graviton. This result pertains to a broad class of theories, including QCD, N=4 SYM, and N=8 supergravity.Comment: 19 pages, 3 figure

One-Loop Amplitudes Of Gluons In SQCD

One-loop amplitudes of gluons in supersymmetric Yang-Mills are four-dimensional cut-constructible. This means that they can be determined from their unitarity cuts. We present a new systematic procedure to explicitly carry out any finite unitarity cut integral. The procedure naturally separates the contributions from bubble, triangle and box scalar integrals. This technique allows the systematic calculation of N=1 amplitudes of gluons. As an application we compute all next-to-MHV six-gluon amplitudes in N=1 super-Yang-Mills.Comment: 49 pages, 4 figures, harvmac. v2: references added, typos fixed. v3: corrections to 3-mass-triangle coefficients, footnote 6 added, acknowledgments added. v4: a typo in formulas for the 3-mass-triangle coefficient is corrected, acknowledgments adde

Multi-frequency, Multi-Epoch Study of Mrk 501: Hints for a two-component nature of the emission

Since the detection of very high energy (VHE) $\gamma$-rays from Mrk 501, its broad band emission of radiation was mostly and quite effectively modeled using one zone emission scenario. However, broadband spectral and flux variability studies enabled by the multiwavelength campaigns carried out during the recent years have revealed rather complex behavior of Mrk 501. The observed emission from Mrk 501 could be due to a complex superposition of multiple emission zones. Moreover new evidences of detection of very hard intrinsic $\gamma$-ray spectra obtained from {\it Fermi}--LAT observations have challenged the theories about origin of VHE $\gamma$-rays. Our studies based on {\it Fermi}--LAT data indicate the existence of two separate components in the spectrum, one for low energy $\gamma$-rays and the other for high energy $\gamma$-rays. Using multiwaveband data from several ground and space based instruments, in addition to HAGAR data, the spectral energy distribution of Mrk~501 is obtained for various flux states observed during 2011. In the present work, this observed broadband spectral energy distribution is reproduced with a leptonic, multi-zone Synchrotron Self-Compton model.Comment: Published in Astrophysical Journal (ApJ

Consistency Conditions on S-Matrix of Spin 1 Massless Particles

Motivated by new techniques in the computation of scattering amplitudes of massless particles in four dimensions, like BCFW recursion relations, the question of how much structure of the S-matrix can be determined from purely S-matrix arguments has received new attention. The BCFW recursion relations for massless particles of spin 1 and 2 imply that the whole tree-level S-matrix can be determined in terms of three-particle amplitudes (evaluated at complex momenta). However, the known proofs of the validity of the relations rely on the Lagrangian of the theory, either by using Feynman diagrams explicitly or by studying the effective theory at large complex momenta. This means that a purely S-matrix theoretic proof of the relations is still missing. The aim of this paper is to provide such a proof for spin 1 particles by extending the four-particle test introduced by P. Benincasa and F. Cachazo in arXiv:0705.4305[hep-th] to all particles. We show how n-particle tests imply that the rational function built from the BCFW recursion relations possesses all the correct factorization channels including holomorphic and anti-holomorphic collinear limits. This in turn implies that they give the correct S-matrix of the theory.Comment: 24 pages, 4 figure

Two-loop Renormalization for Nonanticommutative N=1/2 Supersymmetric WZ Model

We study systematically, through two loops, the divergence structure of the supersymmetric WZ model defined on the N=1/2 nonanticommutative superspace. By introducing a spurion field to represent the supersymmetry breaking term F^3 we are able to perform our calculations using conventional supergraph techniques. Divergent terms proportional to F, F^2 and F^3 are produced (the first two are to be expected on general grounds) but no higher-point divergences are found. By adding ab initio F and F^2 terms to the original lagrangian we render the model renormalizable. We determine the renormalization constants and beta functions through two loops, thus making it possible to study the renormalization group flow of the nonanticommutation parameter.Comment: 36 pages, 25 figures, Latex fil