Superforms in six-dimensional superspace

Indexación: Web of ScienceWe investigate the complex of differential forms in curved, six-dimensional, N = (1, 0) superspace. The superconformal group acts on this complex by super-Weyl transformations. An ambi-twistor-like representation of a second conformal group arises on a pure spinor subspace of the cotangent space. The p-forms are defined by super-Weylcovariant tensor fields on this pure spinor subspace. The on-shell dynamics of such fields is superconformal. We construct the superspace de Rham complex by successively obstructing the closure of forms. We then extend the analysis to composite forms obtained by wedging together forms of lower degree. Finally, we comment on applications to integration in curved superspace and propose a superspace formulation of the abelian limit of the non-abelian tensor hierarchy of N = (1, 0) superconformal models.http://link.springer.com/article/10.1007%2FJHEP05%282016%29016#aboutarticl

Self-dual formulations of d=3 gravity theories in the path-integral framework

We study the connection, at the quantum level, between d=2+1 dimensional self-dual models with actions of growing (from first to fourth) order, governing the dynamics of helicity +2 (or -2) massive excitations. We obtain identities between generating functionals of the different models using the path-integral framework, this allowing to establish dual maps among relevant vacuum expectation values. We check consistency of these v.e.v.'s with the gauge invariance gained in each mapping.Comment: 26 pages. LaTeX. Minor changes. Published in Int. J Modern Phys. A; http://www.worldscinet.com/ijmp

New Results in the CBF theory for medium-heavy nuclei

Momentum distributions, spectroscopic factors and quasi-hole wave functions of medium-heavy doubly closed shell nuclei have been calculated in the framework of the Correlated Basis Function theory, by using the Fermi hypernetted chain resummation techniques. The calculations have been done by using microscopic two-body nucleon-nucleon potentials of Argonne type, together with three-body interactions. Operator dependent correlations, up to the tensor channels, have been used.Comment: 6 pages, 3 figures, proceeding of the "XI Convegno su problemi di Fisica Nucleare Teorica" 11-14 Ottobre 2006, Cortona, Ital

Noise Folding in Compressed Sensing

The literature on compressed sensing has focused almost entirely on settings where the signal is noiseless and the measurements are contaminated by noise. In practice, however, the signal itself is often subject to random noise prior to measurement. We briefly study this setting and show that, for the vast majority of measurement schemes employed in compressed sensing, the two models are equivalent with the important difference that the signal-to-noise ratio is divided by a factor proportional to p/n, where p is the dimension of the signal and n is the number of observations. Since p/n is often large, this leads to noise folding which can have a severe impact on the SNR

Einstein-AdS action, renormalized volume/area and holographic Rényi entropies

Indexación: Scopus.The authors thank D.E. Díaz, P. Sundell and A. Waldron for interesting discussions. C.A. is a Universidad Andres Bello (UNAB) Ph.D. Scholarship holder, and his work is supported by Dirección General de Investigación (DGI-UNAB). This work is funded in part by FONDECYT Grants No. 1170765 “Boundary dynamics in anti-de Sitter gravity and gauge/gravity duality ” and No. 3180620 “Entanglement Entropy and AdS gravity ”, and CONICYT Grant DPI 20140115.We exhibit the equivalence between the renormalized volume of asymptotically anti-de Sitter (AAdS) Einstein manifolds in four and six dimensions, and their renormalized Euclidean bulk gravity actions. The action is that of Einstein gravity, where the renormalization is achieved through the addition of a single topological term. We generalize this equivalence, proposing an explicit form for the renormalized volume of higher even-dimensional AAdS Einstein manifolds. We also show that evaluating the renormalized bulk gravity action on the conically singular manifold of the replica trick results in an action principle that corresponds to the renormalized volume of the regular part of the bulk, plus the renormalized area of a codimension-2 cosmic brane whose tension is related to the replica index. Renormalized Rényi entropy of odd-dimensional holographic CFTs can thus be obtained from the renormalized area of the brane with finite tension, including the effects of its backreaction on the bulk geometry. The area computation corresponds to an extremization problem for an enclosing surface that extends to the AdS boundary, where the newly defined renormalized volume is considered. © 2018, The Author(s).https://link.springer.com/article/10.1007%2FJHEP08%282018%2913

Ground state of medium-heavy doubly-closed shell nuclei in correlated basis function theory

The correlated basis function theory is applied to the study of medium-heavy doubly closed shell nuclei with different wave functions for protons and neutrons and in the jj coupling scheme. State dependent correlations including tensor correlations are used. Realistic two-body interactions of Argonne and Urbana type, together with three-body interactions have been used to calculate ground state energies and density distributions of the 12C, 16O, 40Ca, 48Ca and 208Pb nuclei.Comment: Latex 10 pages, 3 Tables, 10 Figure

Cuantificación de los flujos de asistencia: un nuevo enfoque

(Disponible en idioma inglés únicamente) La discusión sobre la eficacia de la asistencia externa se ha intensificado en los últimos años, en la medida en que la asistencia ha venido experimentando cada vez más presiones presupuestarias en los países donantes. Independientemente de los méritos de los argumentos en contra, el problema de fondo surge de si las medidas de asistencia que se emplean convencionalmente, tales como la ODA, que agrupa las donaciones y los préstamos, reflejan con precisión los flujos de asistencia reales. En este trabajo se analizan las deficiencias metodológicas de las medidas convencionales de la asistencia y se propone un nuevo enfoque de valoración que cuantifique los flujos de asistencia oficial como la suma de las donaciones y los equivalentes de donaciones de los préstamos oficiales. Esta medición de la asistencia, conceptualmente superior, puede distanciarse considerablemente de los agregados convencionales y dar una idea muy distinta de las principales tendencias de la asistencia.