Yang-Mills Chern-Simons Corrections From the Pure Spinor Superstring

Nilpotency of the pure spinor BRST operator in a curved background implies superspace equations of motion for the background. By computing one-loop corrections to nilpotency for the heterotic sigma model, the Yang-Mills Chern-Simons corrections to the background are derived.Comment: 25 pages, harvmac tex, 15 diagrams; references adde

El exilio vivido por los personajes en la Isla de la pasión

En el presente artículo se pretende analizar cómo la novela La isla de la pasión de Laura Restrepo configura una metáfora del exilio a partir del relato de la historia de un grupo de soldados que conviven, sueñan y sufren en medio de unas condiciones inhóspitas en una isla abandonada -- Para confirmar la tesis se realiza un estudio detallado y minucioso de la obra a través de un análisis e interpretación de algunas citas -- Como primera parte del artículo está una breve presentación de la novela anunciada -- Luego se despliegan los temas de La isla de la pasión como exilio, La isla de la pasión como relato de viaje y el papel de las mujeres en La isla de la pasión realizando una exegesis sobre la relación de éstos y la metáfora del exilio en la novel

Deuteron properties from muonic atom spectroscopy

Leading order ($\alpha^4$) finite size corrections in muonic deuterium are evaluated within a few body formalism for the $\mu^- p n$ system in muonic deuterium and found to be sensitive to the input of the deuteron wave function. We show that this sensitivity, taken along with the precise deuteron charge radius determined from muonic atom spectroscopy can be used to determine the elusive deuteron D-state probability, $P_D$, for a given model of the nucleon-nucleon (NN) potential. The radius calculated with a $P_D$ of 4.3\% in the chiral NN models and about 5.7\% in the high precision NN potentials is favoured most by the $\mu^-d$ data.Comment: 14 pages, 2 figure

Heterotic α\alpha'-corrections in Double Field Theory

We extend the generalized flux formulation of Double Field Theory to include all the first order bosonic contributions to the $\alpha '$ expansion of the heterotic string low energy effective theory. The generalized tangent space and duality group are enhanced by $\alpha'$ corrections, and the gauge symmetries are generated by the usual (gauged) generalized Lie derivative in the extended space. The generalized frame receives derivative corrections through the spin connection with torsion, which is incorporated as a new degree of freedom in the extended bein. We compute the generalized fluxes and find the Riemann curvature tensor with torsion as one of their components. All the four-derivative terms of the action, Bianchi identities and equations of motion are reproduced. Using this formalism, we obtain the first order $\alpha'$ corrections to the heterotic Buscher rules. The relation of our results to alternative formulations in the literature is discussed and future research directions are outlined.Comment: Published versio

Rafael del Águila: Crítica de las ideologías. El peligro de los ideales. Taurus, Madrid, 2008

Sin resume

On Quasibound N* Nuclei

The possibility for the existence of unstable bound states of the S11 nucleon resonance N$^*$(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N$^*$ interaction involving a pion and eta meson exchange, N$^*$-nucleus potentials for N*-$^3$He and N*-$^{24}$Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-$^3$He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N$^*$ $\pi$ and N N$^*$ $\eta$ vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with $\Gamma \sim$ 80 and 110 MeV for N*-$^3$He and N*-$^{24}$Mg respectively.Comment: Presented at the Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Cracow, Poland, June 2015; to be published in Acta Physica Polonica B (2016