Cosmological Probes for Supersymmetry

The multi-parameter character of supersymmetric dark-matter models implies the combination of their experimental studies with astrophysical and cosmological probes. The physics of the early Universe provides nontrivial effects of non-equilibrium particles and primordial cosmological structures. Primordial black holes (PBHs) are a profound signature of such structures that may arise as a cosmological consequence of supersymmetric (SUSY) models. SUSY-based mechanisms of baryosynthesis can lead to the possibility of antimatter domains in a baryon asymmetric Universe. In the context of cosmoparticle physics, which studies the fundamental relationship of the micro- and macro-worlds, the development of SUSY illustrates the main principles of this approach, as the physical basis of the modern cosmology provides cross-disciplinary tests in physical and astronomical studies.Comment: Invited review to the special issue "Supersymmetry and Dark matter" (ed. D.Cline) of the Symmetry journal. arXiv admin note: substantial text overlap with arXiv:0801.0116, arXiv:1311.246

Forecasting day-ahead electricity prices in Europe: the importance of considering market integration

Motivated by the increasing integration among electricity markets, in this paper we propose two different methods to incorporate market integration in electricity price forecasting and to improve the predictive performance. First, we propose a deep neural network that considers features from connected markets to improve the predictive accuracy in a local market. To measure the importance of these features, we propose a novel feature selection algorithm that, by using Bayesian optimization and functional analysis of variance, evaluates the effect of the features on the algorithm performance. In addition, using market integration, we propose a second model that, by simultaneously predicting prices from two markets, improves the forecasting accuracy even further. As a case study, we consider the electricity market in Belgium and the improvements in forecasting accuracy when using various French electricity features. We show that the two proposed models lead to improvements that are statistically significant. Particularly, due to market integration, the predictive accuracy is improved from 15.7% to 12.5% sMAPE (symmetric mean absolute percentage error). In addition, we show that the proposed feature selection algorithm is able to perform a correct assessment, i.e. to discard the irrelevant features

Crecimiento y relación tamaño-edad del palmito (Euterpe edulis) en selvas aprovechadas y protegidas en el noreste de Misiones, Argentina

Euterpe edulis Mart. (Arecaceae), habita la selva Misionera en Argentina, tanto en áreas protegidas como en aquellas bajo aprovechamiento. Esta palmera se corta para extraer el palmito que es un alimento gourmet. Se estudió el crecimiento y se estimó la edad de los individuos utilizando 3 parcelas permanentes de una hectárea cada una. Dos parcelas se establecieron en el Parque Nacional Iguazú y otra en una propiedad privada donde se había realizado aprovechamiento de esta especie. Para cada palmera marcada se midió el crecimiento del tronco (altura y diámetro) por 3 años y se compararon los incrementos de aquellos viviendo en el Parque Nacional con los que prosperaron en el sitio aprovechado. Se realizaron regresiones para estimar la relación entre el incremento en tamaño y el área basal de la selva. Las palmeras se clasificaron en 5 categorías. Los parámetros de las regresiones se utilizaron para estimar el tiempo que un palmito necesita para alcanzar el tamaño para ser aprovechado. Las palmeras de un mismo tamaño pueden ser de diferente edad dependiendo del sitio donde viven. En Argentina, la ley permite cortar individuos con DAP igual o mayor a 10 cm. En sitios aprovechados, las palmeras alcanzan este tamaño a los 23 años de edad o menos, mientras que el Parque Nacional este tamaño se alcanza a los 50 años o más. El aprovechamiento de palmitos de 10 cm de DAP puede ser sustentable, sin embargo el ciclo de corta dependerá del tipo de ambiente.The Euterpe edulis Mart. (Arecaceae) occurs both in protected and logged areas of the Atlantic forest in Misiones, Argentina. This palm tree is harvested for its heart. To study the growth and estimate the age of E. edulis individuals, three one-hectare permanent plots were used: two of them located in the Iguazú National Park and the third, a private one, where this species had been harvested. Each marked individual was measured against those of the individuals in the harvested private site in its stem growth (height and diameter) for three years and their increase compared. To estimate the relationship growth increase to forest basal area of the forest, regressions were made. The palm trees were classified into five categories. The regression parameters were used to estimate the time a palm heart takes to become harvestable. Palm tree growth for each size category was related to harvestable palm basal area per hectare. Palm trees of the same size may be of different ages depending on where they grew. In Argentina, law allows palm trees to be harvested when their DBH is 10 cm or more. In logged areas, palm trees reach this size in 23 years or earlier, while in protected areas it takes them 50 years or more. Harvesting palm trees with 10 cm of DBH can be a sustainable practice. However, the cutting time will depend on the environment where palms grow.Fil: Chediack, Sandra Emilia. No especifica;Fil: Gatti, Maria Genoveva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentin

Ultrarelativistic Bondi--Hoyle Accretion I: Axisymmetry

An ultrarelativistic relativistic study of axisymmetric Bondi--Hoyle accretion onto a moving Kerr black hole is presented. The equations of general relativistic hydrodynamics are solved using high resolution shock capturing methods. In this treatment we consider the ultrarelativistic limit wherein one may neglect the baryon rest mass density. This approximation is valid in the regime where the internal energy of the system dominates over the rest mass energy contribution from the baryons. The parameters of interest in this study are the adiabatic constant $\Gamma$, and the asymptotic speed of the fluid, $v_\infty$. We perform our simulations in three different regimes, subsonic, marginally supersonic, and supersonic, but the primary focus of this study is the parameter regime in which the flow is supersonic, that is when $v_\infty \ge c_{s}^{\infty}$. As expected from previous studies the supersonic regimes reveal interesting dynamics, but even more interesting is the presence of a bow shock in marginally supersonic systems. A range of parameter values were investigated to attempt to capture possible deviations from steady state solutions, none were found. To show the steady state behaviour of each of the flows studied we calculate the energy accretion rates on the Schwarzschild radius. Additionally, we also find that the accretion flows are dependent on the location of the computational boundary, that if the computational boundary is located too close to the black hole the calculated flow profiles are marred with numerical artifacts. This is a problem not found in previous relativistic models for ultrarelativistic hydrodynamic systems.Comment: 16 pages, 15 figures, Typos correcte

Fundamental Particle Structure in the Cosmological Dark Matter

The nonbaryonic dark matter of the Universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro world and mechanisms of its symmetry breaking. Particle candidates for cosmological dark matter are lightest particles that bear new conserved quantum numbers. Dark matter particles may represent ideal gas of non-interacting particles. Self-interacting dark matter weakly or superweakly coupled to ordinary matter is also possible, reflecting nontrivial pattern of particle symmetry in the hidden sector of particle theory. In the early Universe the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which macroscopic cosmological defects or primordial nonlinear structures can be originated. Primordial black holes (PBHs) can be not only a candidate for dark matter, but also represent a universal probe for super-high energy physics in the early Universe. Evaporating PBHs turn to be a source of even superweakly interacting particles, while clouds of massive PBHs can serve as a nonlinear seeds for galaxy formation. The observed broken symmetry of the three known families may provide a simultaneous solution for the problems of the mass of neutrino and strong CP violation in the unique framework of models of horizontal unification. The existence of new stable charged leptons and quarks is possible, hidden in elusive "dark atoms". Such possibility, strongly restricted by the constraints on anomalous isotopes of light elements, is not excluded in scenarios that predict stable double charged particles. The excessive -2 charged particles are bound in these scenarios with primordial helium in O-helium "atoms", maintaining specific nuclear-interacting form of the dark matter, which may provide an interesting solution for the puzzles of the direct dark matter searches. (abridged)Comment: Invited review to International Journal of Modern Physics

Dynamics of Primordial Black Hole Formation

We present a numerical investigation of the gravitational collapse of horizon-size density fluctuations to primordial black holes (PBHs) during the radiation-dominated phase of the Early Universe. The collapse dynamics of three different families of initial perturbation shapes, imposed at the time of horizon crossing, is computed. The perturbation threshold for black hole formation, needed for estimations of the cosmological PBH mass function, is found to be $\delta_{\rm c} \approx 0.7$ rather than the generally employed $\delta_{\rm c} \approx 1/3$, if $\delta$ is defined as \Delta M/\mh, the relative excess mass within the initial horizon volume. In order to study the accretion onto the newly formed black holes, we use a numerical scheme that allows us to follow the evolution for long times after formation of the event horizon. In general, small black holes (compared to the horizon mass at the onset of the collapse) give rise to a fluid bounce that effectively shuts off accretion onto the black hole, while large ones do not. In both cases, the growth of the black hole mass owing to accretion is insignificant. Furthermore, the scaling of black hole mass with distance from the formation threshold, known to occur in near-critical gravitational collapse, is demonstrated to apply to primordial black hole formation.Comment: 10 pages, 8 figures, revtex style, submitted to PR

Exact controllability of multiplex networks

Date of Acceptance: 11/09/2014Peer reviewedPublisher PD

Nonlinear Eigenvalue Approach to Differential Riccati Equations for Contraction Analysis

In this paper, we extend the eigenvalue method of the algebraic Riccati equation to the differential Riccati equation (DRE) in contraction analysis. One of the main results is showing that solutions to the DRE can be expressed as functions of nonlinear eigenvectors of the differential Hamiltonian matrix. Moreover, under an assumption for the differential Hamiltonian matrix, real symmetricity, regularity, and positive semidefiniteness of solutions are characterized by nonlinear eigenvalues and eigenvectors