Vacuum field energy and spontaneous emission in anomalously dispersive cavities

Anomalously dispersive cavities, particularly white light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, their use has been proposed for use in LIGO-like gravity wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed $\hbar \omega/2$. For white light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.Comment: 9 pages, 4 figure

Dualization of non-Abelian BF model

We show that dualization of BF models to Stueckelberg-like massive gauge theories allows a non-Abelian extension. We obtain local Lagrangians which are straightforward extensions of the Abelian results.Comment: 6 pages, ReVTeX, no figures, to be publ. on Phys.Lett.

Can the Type-IIB axion prevent Pre-big Bang inflation?

We look at the possibility of superinflationary behavior in a class of anisotropic Type-IIB superstring cosmologies in the context of Pre-big Bang scenario and find that there exists a rather narrow range of parameters for which these models inflate. We then show that, although in general this behavior is left untouched by the introduction of a Ramond-Ramond axion field through a SL(2,R) rotation, there exists a particular class of axions for which inflation disappears completely. Asymptotic past initial conditions are briefly discussed, and some speculations on the possible extension of Pre-big Bang ideas to gravitational collapse are presented.Comment: harvmac, epsf. 3 figures include

Registro del caracol africano gigante Achatina fulica (Bowdich 1822) (Mollusca: Gastropoda-Achatinidae) en Sincelejo, costa Caribe de Colombia

Its registers for the first time the presence of the African giant snail, Achatina fulica (Bowdich 1822) in Sincelejo city, department of Sucre, Caribbean coast of Colombia. The first invasion alert in the country was given by Corpoamazonia in August of 2010, for introduction of snails coming from Brazil. Then in the year 2011 was reported the occurrence in the departments of Arauca, Boyacá, Caquetá, Casanare, Guainía, Huila, Meta, Nariño, Putumayo, Santander, Tolima, Valle del Cauca and Vaupés. In the 2012 it was located in the department of Antioquia. This new discovery in the department of Sucre alerts because its presence in the Colombian Caribbean begins to be certain.Se registra por primera vez la presencia del caracol gigante africano, Achatina fulica (Bowdich 1822) en la ciudad de Sincelejo, departamento de Sucre, costa Caribe de Colombia. La primera alerta de invasión en el país fue dada por Corpoamazonia en agosto de 2010, por la introducción de ejemplares provenientes de Brasil. Luego la especie reapareció en 2011 en los departamentos de Arauca, Boyacá, Caquetá, Casanare, Guainía, Huila, Meta, Nariño, Putumayo, Santander, Tolima, Valle del Cauca y Vaupés. En 2012 fue localizada en el departamento de Antioquia. Este nuevo hallazgo en el departamento de Sucre, alerta porque su presencia en el Caribe colombiano empieza a manifestarse

Registro del caracol africano gigante <em>Achatina fulica<em> (Bowdich 1822) (Mollusca: Gastropoda-Achatinidae) en Sincelejo, costa Caribe de Colombia

Its registers for the first time the presence of the African giant snail, Achatina fulica (Bowdich 1822) in Sincelejo city, department of Sucre, Caribbean coast of Colombia. The first invasion alert in the country was given by Corpoamazonia in August of 2010, for introduction of snails coming from Brazil. Then in the year 2011 was reported the occurrence in the departments of Arauca, Boyacá, Caquetá, Casanare, Guainía, Huila, Meta, Nariño, Putumayo, Santander, Tolima, Valle del Cauca and Vaupés. In the 2012 it was located in the department of Antioquia. This new discovery in the department of Sucre alerts because its presence in the Colombian Caribbean begins to be certain

ArgoNeuT, a liquid argon time projection chamber in a low energy neutrino beam

ArgoNeuT (Argon Neutrino Test), a NSF/DOE project at Fermilab, is the first LArTPC to go in a low energy neutrino beam and just the second LArTPC to go in a neutrino beam ever. ArgoNeuT sits just upstream of the on-axis MINOS near detector in the NuMI beamline, about 1 km from the target station and 100 m underground. The detector features a 47X40X90 cm (169 L) active volume TPC with a fully contained recirculation and purification system. Among other physics, ArgoNeuT will measure the charged-current quasi-elastic (anti-) neutrino cross section on argon at an energy of ~3 GeV.Comment: 3 pages, 2 figures, to appear in the proceedings of the 11th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2009), Rome, Italy, 1-5 July 200

Actividades y estrategias para hacerse a los medios de vida de una familia en el área rural de la depresión momposina, colombia

The means of life of a family of the rural area of the Momposina depression region, Colombia were analyzed. It was found that inside the assets, the social, natural and human capital, they give the sustainability, while the physical capital and financier are those that present bigger weakness that which does not allow concluding that sustainable exists to complete the objectives as regards means of life. It is evidenced that the integration among the different variables that compose the means of life should be related in a positive way to reach the sustainable.Se analizan los medios de vida de una familia del área rural de la depresión momposina, Colombia. Se encontró que dentro de los activos, el capital social, natural y humano, dan la sustentabilidad, mientras que el capital físico y financiero son los que presentan mayor debilidad, lo cual no permite concluir que exista sostenibilidad para cumplir los objetivos en materia de medios de vida. Se evidencia que la integración entre las diferentes variables que componen los medios de vida se relacionan de forma positiva para alcanzar la sostenibilidad

Wakefield-Induced Ionization injection in beam-driven plasma accelerators

We present a detailed analysis of the features and capabilities of Wakefield-Induced Ionization (WII) injection in the blowout regime of beam driven plasma accelerators. This mechanism exploits the electric wakefields to ionize electrons from a dopant gas and trap them in a well-defined region of the accelerating and focusing wake phase, leading to the formation of high-quality witness-bunches [Martinez de la Ossa et al., Phys. Rev. Lett. 111, 245003 (2013)]. The electron-beam drivers must feature high-peak currents ($I_b^0\gtrsim 8.5~\mathrm{kA}$) and a duration comparable to the plasma wavelength to excite plasma waves in the blowout regime and enable WII injection. In this regime, the disparity of the magnitude of the electric field in the driver region and the electric field in the rear of the ion cavity allows for the selective ionization and subsequent trapping from a narrow phase interval. The witness bunches generated in this manner feature a short duration and small values of the normalized transverse emittance ($k_p\sigma_z \sim k_p\epsilon_n \sim 0.1$). In addition, we show that the amount of injected charge can be adjusted by tuning the concentration of the dopant gas species, which allows for controlled beam loading and leads to a reduction of the total energy spread of the witness beams. Electron bunches, produced in this way, fulfil the requirements to drive blowout regime plasma wakes at a higher density and to trigger WII injection in a second stage. This suggests a promising new concept of self-similar staging of WII injection in steps with increasing plasma density, giving rise to the potential of producing electron beams with unprecedented energy and brilliance from plasma-wakefield accelerators

Toric Calabi-Yau Fourfolds, Duality Between N=1 Theories and Divisors that Contribute to the Superpotential

We study issues related to F-theory on Calabi-Yau fourfolds and its duality to heterotic theory for Calabi-Yau threefolds. We discuss principally fourfolds that are described by reflexive polyhedra and show how to read off some of the data for the heterotic theory from the polyhedron. We give a procedure for constructing examples with given gauge groups and describe some of these examples in detail. Interesting features arise when the local pieces are fitted into a global manifold. An important issue is how to compute the superpotential explicitly. Witten has shown that the condition for a divisor to contribute to the superpotential is that it have arithmetic genus 1. Divisors associated with the short roots of non-simply laced gauge groups do not always satisfy this condition while the divisors associated to all other roots do. For such a `dissident' divisor we distinguish cases for which the arithmetic genus is greater than unity corresponding to an X that is not general in moduli (in the toric case this corresponds to the existence of non-toric parameters). In these cases the `dissident' divisor D does not remain an effective divisor for general complex structure. If however the arithmetic genus is less than or equal to 0, then the divisor is general in moduli and there is a genuine instability