Accretion of Ghost Condensate by Black Holes

The intent of this letter is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion rate is set not by the cosmological energy density of the field, but by the energy scale of the ghost condensate theory. If hydrodynamical flow is established, it could be as high as tenth of a solar mass per second for 10MeV-scale ghost condensate accreting onto a stellar-sized black hole, which puts serious constraints on the parameters of the ghost condensate model.Comment: 5 pages, 3 figures, REVTeX 4.0; discussion expande

Supersymmetry-Breaking Loops from Analytic Continuation into Superspace

We extend to all orders in perturbation theory a method to calculate supersymmetry-breaking effects by analytic continuation of the renormalization group into superspace. A central observation is that the renormalized gauge coupling can be extended to a real vector superfield, thereby including soft breaking effects in the gauge sector. We explain the relation between this vector superfield coupling and the "holomorphic" gauge coupling, which is a chiral superfield running only at 1 loop. We consider these issues for a number of regulators, including dimensional reduction. With this method, the renormalization group equations for soft supersymmetry breaking terms are directly related to supersymmetric beta functions and anomalous dimensions to all orders in perturbation theory. However, the real power of the formalism lies in computing finite soft breaking effects corresponding to high-loop component calculations. We prove that the gaugino mass in gauge-mediated supersymmetry breaking is ``screened'' from strong interactions in the messenger sector. We present the complete next-to-leading calculation of gaugino masses (2 loops) and sfermion masses (3 loops) in minimal gauge mediation, and several other calculations of phenomenological relevance.Comment: 50 pages, 1 ps and 1 eps figure, LaTe

Local Spacetime Physics from the Grassmannian

A duality has recently been conjectured between all leading singularities of n-particle N^(k-2)MHV scattering amplitudes in N=4 SYM and the residues of a contour integral with a natural measure over the Grassmannian G(k,n). In this note we show that a simple contour deformation converts the sum of Grassmannian residues associated with the BCFW expansion of NMHV tree amplitudes to the CSW expansion of the same amplitude. We propose that for general k the same deformation yields the (k-2) parameter Risager expansion. We establish this equivalence for all MHV-bar amplitudes and show that the Risager degrees of freedom are non-trivially determined by the GL(k-2) "gauge" degrees of freedom in the Grassmannian. The Risager expansion is known to recursively construct the CSW expansion for all tree amplitudes, and given that the CSW expansion follows directly from the (super) Yang-Mills Lagrangian in light-cone gauge, this contour deformation allows us to directly see the emergence of local space-time physics from the Grassmannian.Comment: 22 pages, 13 figures; v2: minor updates, typos correcte

Relaxing to a three dimensional brane junction

We suggest a mechanism which leads to 3+1 space-time dimensions. The Universe assumed to have nine spatial dimensions is regarded as a special nonlinear oscillatory system -- a kind of Einstein solid. There are p-brane solutions which manifest as phase oscillations separating different phase states. The presence of interactions allows for bifurcations of higher dimensional spaces to lower dimensional ones in the form of brane junctions. We argue this is a natural way to select lower dimensions.Comment: RevTex, 5 pages; version to appear in Europhys. Let

Gluon Tree Amplitudes in Open Twistor String Theory

We show how the link variables of Arkani-Hamed, Cachazo, Cheung and Kaplan (ACCK), can be used to compute general gluon tree amplitudes in the twistor string. They arise from instanton sectors labelled by d, with d=n-1, where n is the number of negative helicities. Read backwards, this shows how the various forms for the tree amplitudes studied by ACCK can be grouped into contour integrals whose structure implies the existence of an underlying string theory.Comment: 36 page

Efficient Single Photon Absorption by Optimized Superconducting Nanowire Geometries

We report on simulation results that shows optimum photon absorption by superconducting nanowires can happen at a fill-factor that is much less than 100%. We also present experimental results on high performance of our superconducting nanowire single photon detectors realized using NbTiN on oxidized silicon.Comment: \copyright 2013 IEEE. Submitted to "Numerical Simulation of Optoelectronic Devices - NUSOD 2013" on 19-April-201

Impact of Molarity on the Structural, Morphological and Optical Properties of CeO2 Thin Films Prepared by Spray Pyrolysis Technique

CeO2 thin films are deposited on glass substrate by spray pyrolysis technique (SPT) at 623 K using different molar concentration of cerium chloride precursor solution. The structural, morphological and optical properties of films were investigated by a set of characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM),UV-VIS-IR. The estimation of crystallite size is 80-120 nm, which is confirmed by Scherer formulae from XRD pattern. XRD analysis shows that the film has cubic fluorite phase with orientation along (111) for all molarity. The optical energy gap decreased with the increase of crystallite size (98-120 nm) due to the size effect

Efecto sobre la oxidación de triglicéridos purificados del aceite de girasol, del extracto de acetona del fruto de Maclura pomifera, de la pomiferina y de la osajina

omiferin and osajin have been isolated from the acetonic extract of M. pomifera fruits. Effects of total acetonic extract, pomiferin and osajin on the autooxidation of purified sunflower triacylglycerol were studied. Pomiferin showed a high antioxidant activity whereas total acetonic extract showed moderate and osajin revealed a low activity.Se han aislado la pomiferina y la osajina del extracto de hexano del fruto de M. pomifera. Se han estudiado los efectos sobre la oxidación de triglicéridos purificados del aceite de girasol, del extracto de acetona, de la pomiferina y de la osajina. La pomiferina mostró una actividad antioxidante elevada en cambio, el extracto de acetona mostró una actividad moderada y la osajina baja

Bounds on models with one latticized extra dimension

We study an extension of the standard model with one latticized extra dimension accessible to all fields. The model is characterized by the size of the extra dimension and the number of sites, and contains a tower of massive particles. At energies lower than the mass of the new particles there are no tree-level effects. Therefore, bounds on the scale of new physics can only be set from one-loop processes. We calculate several observables sensitive to loop-effects, such as the $\rho$ parameter, $b\to s \gamma$, $Z\to b\bar b$, and the $B^0\rightleftharpoons\bar{B}^0$ mixing, and use them to set limits on the lightest new particles for different number of sites. It turns out that the continuous result is rapidly reached when the extra dimension is discretized in about 10 to 20 sites only. For small number of sites the bounds placed on the usual continuous scenario can be reduced by roughly a factor of 10%--25%, which means that the new particles can be as light as $320 {GeV}$. Finally, we briefly discuss an alternative model in which fermions do not have additional modes.Comment: 23 pages, 6 figure