A Nonequilibrium Thermodynamic Approach to Generalized Statistics for Brownian Motion

We analyze the dynamics of a Brownian gas in contact with a heat bath in which large temperature fluctuations occur. There are two distinct time scales present, one describes the decay of the fluctuations in the temperature and the other one is associated with the establishment of local equilibrium. Although the gas has reached local equilibrium, there exist large fluctuations in an intensive parameter (temperature) which break the thermodynamic equilibrium with the heat bath. Thus the decay of the fluctuations in the intensive parameter is larger than the characteristic time for the establishment of local equilibrium. We show that the dynamics of such large and intensive fluctuations may be described by adopting a nonequilibrium thermodynamics approach with an adequate formulation of local equilibrium. A coarsening procedure is then used to contract the space of mesoscopic variables needed to describe the dynamics of the gas and the extensive character of the description is lost. This procedure allows us to derive an effective Maxwell-Boltzmann factor (EMBF) for the Brownian gas, as has been recently proposed in the literature. Furthermore, we use this local equilibrium distribution and an entropy functional to derive a nonequilibrium probability distribution and a hydrodynamic description for the Brownian gas which contains fluctuating transport coefficients. The ensuing description is nonextensive and our analysis shows that the coarse-graining procedure is responsible for the nonextensivity property.Comment: 13 page

Realistic Neutrino Opacities for Supernova Simulations With Correlations and Weak Magnetism

Advances in neutrino transport allow realistic neutrino interactions to be incorporated into supernova simulations. We add tensor couplings to relativistic RPA calculations of neutrino opacities. Our results reproduce free-space neutrino-nucleon cross sections at low density, including weak magnetism and recoil corrections. In addition, our opacities are thermodynamically consistent with relativistic mean field equations of state. We find antineutrino mean free paths that are considerably larger then those for neutrinos. This difference depends little on density. In a supernova, this difference could lead to an average energy of $\bar\nu_\mu$ that is larger than that for $\nu_\mu$ by an amount that is comparable to the energy difference between $\nu_\mu$ and $\bar\nu_e$Comment: 15 pages, 10 figures, submitted to PRC, minor changes to figs. (9,10

Unbounded violation of tripartite Bell inequalities

We prove that there are tripartite quantum states (constructed from random unitaries) that can lead to arbitrarily large violations of Bell inequalities for dichotomic observables. As a consequence these states can withstand an arbitrary amount of white noise before they admit a description within a local hidden variable model. This is in sharp contrast with the bipartite case, where all violations are bounded by Grothendieck's constant. We will discuss the possibility of determining the Hilbert space dimension from the obtained violation and comment on implications for communication complexity theory. Moreover, we show that the violation obtained from generalized GHZ states is always bounded so that, in contrast to many other contexts, GHZ states do in this case not lead to extremal quantum correlations. The results are based on tools from the theories of operator spaces and tensor norms which we exploit to prove the existence of bounded but not completely bounded trilinear forms from commutative C*-algebras.Comment: Substantial changes in the presentation to make the paper more accessible for a non-specialized reade

Nuevos modelos de predicción del incremento en volumen para bosques mezclados del Estado de Durango, México

Thirty models were evaluated to predict the timber yield in 28 Permanent Silvicultural Research Plots (SPIS), in the Ejido Pueblo, Durango, Mexico. The most predominant plant association is the corresponding to mixed stands of Pinus and Pinus-Quercus, besides the vegetation associated to these forests. The models in their logarithmic form incorporate 10 competition indexes (IC) independent of the distance, 3 indexes of density (ID), besides the variable age and height at the average level of the stand. The new mathematical models relate in an indirect way the effect of the competition and the density in the growth of trees present in the stand. According to the variance analyses and the hypothesis tests, it was found that the best IC incorporated in a mathematical model for the prediction of the increment in volume was the competition index of area basal density (IABN), the competition index of diameter quadratic density (IDCN), the competition index of area basal total density (IABTN) and the competition index of maximum total height (IHMAX). The best models present a high level of accuracy with Prob > |t| = 0.0001 and values average of 0.99 in R2. The best models presented average values of R2 = 0.99 and a highly significant level of accuracy (Pr > |t| = 0.0001).Fueron evaluados 30 modelos para predecir el incremento maderable en 28 Sitios Permanentes de Investigación Silvícola (SPIS), ubicados en el Ejido Pueblo Nuevo del Estado de Durango, México. La asociación vegetal más predominante es la correspondiente a rodales mezclados de Pinus y Pinus-Quercus, además de la vegetación asociada a estos bosques. Los modelos en su forma logarítmica incorporan 10 índices de competencia (IC) independientes de la distancia, 3 índices de densidad (ID), además de las variables edad y altura a nivel promedio del rodal. Los nuevos modelos matemáticos relacionan de una manera indirecta el efecto de la competencia y la densidad en el crecimiento de los arboles presentes en el rodal. De acuerdo con los análisis de varianza y las pruebas de hipótesis realizadas, se encontró que los mejores IC incorporados en un modelo matemático para la predicción del incremento en volumen, fueron el índice de competencia de área basal densidad (IABN), índice de competencia de diámetro cuadrático densidad (IDCN), índice de competencia de área basal total densidad (IABTN) y el índice de competencia de altura total máxima (IHMAX). Los mejores modelos presentan un alto nivel de exactitud con Prob > |t| = 0,0001 y valores promedio de 0,99 en R2

Tools for Deconstructing Gauge Theories in AdS5

We employ analytical methods to study deconstruction of 5D gauge theories in the AdS5 background. We demonstrate that using the so-called q-Bessel functions allows a quantitative analysis of the deconstructed setup. Our study clarifies the relation of deconstruction with 5D warped theories.Comment: 30 pages; v2: several refinements, references adde

Vacuum Polarization Effects in the Lorentz and PCT Violating Electrodynamics

In this work we report new results concerning the question of dynamical mass generation in the Lorentz and PCT violating quantum electrodynamics. A one loop calculation for the vacuum polarization tensor is presented. The electron propagator, "dressed" by a Lorentz breaking extra term in the fermion Lagrangian density, is approximated by its first order: this scheme is shown to break gauge invariance. Then we rather consider a full calculation to second order in the Lorentz breaking parameter: we recover gauge invariance and use the Schwinger-Dyson equation to discuss the full photon propagator. This allows a discussion on a possible photon mass shift as well as measurable, observable physical consequences, such as the Lamb-shift.Comment: Latex file, 19 pages, no figures, includes PACS number

Unital Quantum Channels - Convex Structure and Revivals of Birkhoff's Theorem

The set of doubly-stochastic quantum channels and its subset of mixtures of unitaries are investigated. We provide a detailed analysis of their structure together with computable criteria for the separation of the two sets. When applied to O(d)-covariant channels this leads to a complete characterization and reveals a remarkable feature: instances of channels which are not in the convex hull of unitaries can return to it when either taking finitely many copies of them or supplementing with a completely depolarizing channel. In these scenarios this implies that a channel whose noise initially resists any environment-assisted attempt of correction can become perfectly correctable.Comment: 31 page

Large violation of Bell inequalities with low entanglement

In this paper we obtain violations of general bipartite Bell inequalities of order $\frac{\sqrt{n}}{\log n}$ with $n$ inputs, $n$ outputs and $n$-dimensional Hilbert spaces. Moreover, we construct explicitly, up to a random choice of signs, all the elements involved in such violations: the coefficients of the Bell inequalities, POVMs measurements and quantum states. Analyzing this construction we find that, even though entanglement is necessary to obtain violation of Bell inequalities, the Entropy of entanglement of the underlying state is essentially irrelevant in obtaining large violation. We also indicate why the maximally entangled state is a rather poor candidate in producing large violations with arbitrary coefficients. However, we also show that for Bell inequalities with positive coefficients (in particular, games) the maximally entangled state achieves the largest violation up to a logarithmic factor.Comment: Reference [16] added. Some typos correcte