Absorption and Direct Processes in Chaotic Wave Scattering

Recent results on the scattering of waves by chaotic systems with losses and direct processes are discussed. We start by showing the results without direct processes nor absorption. We then discuss systems with direct processes and lossy systems separately. Finally the discussion of systems with both direct processes and loses is given. We will see how the regimes of strong and weak absorption are modified by the presence of the direct processes.Comment: 8 pages, 4 figures, Condensed Matter Physics (IV Mexican Meeting on Mathematical and Experimental Physics), Edited by M. Martinez-Mares and J. A. Moreno-Raz

Electromagnetic prompt response in an elastic wave cavity

A rapid, or prompt response, of an electromagnetic nature, is found in an elastic wave scattering experiment. The experiment is performed with torsional elastic waves in a quasi-one-dimensional cavity with one port, formed by a notch grooved at a certain distance from the free end of a beam. The stationary patterns are diminished using a passive vibration isolation system at the other end of the beam. The measurement of the resonances is performed with non-contact electromagnetic-acoustic transducers outside the cavity. In the Argand plane, each resonance describes a circle over a base impedance curve which comes from the electromagnetic components of the equipment. A model, based on a variation of Poisson's kernel is developed. Excellent agreement between theory and experiment is obtained.Comment: 4 pages, 5 figure

Scattering of Elastic Waves in a Quasi-one-dimensional Cavity: Theory and Experiment

We study the scattering of torsional waves through a quasi-one-dimensional cavity both, from the experimental and theoretical points of view. The experiment consists of an elastic rod with square cross section. In order to form a cavity, a notch at a certain distance of one end of the rod was grooved. To absorb the waves, at the other side of the rod, a wedge, covered by an absorbing foam, was machined. In the theoretical description, the scattering matrix S of the torsional waves was obtained. The distribution of S is given by Poisson's kernel. The theoretical predictions show an excellent agreement with the experimental results. This experiment corresponds, in quantum mechanics, to the scattering by a delta potential, in one dimension, located at a certain distance from an impenetrable wall

Dynamical quark recombination in ultrarelativistic heavy-ion collisions and the proton to pion ratio

We study quark thermal recombination as a function of energy density during the evolution of a heavy-ion collision in a numerical model that reproduces aspects of QCD phenomenology. We show that starting with a set of free quarks (or quarks and antiquarks) the probability to form colorless clusters of three quarks differs from that to form colorless clusters of quark-antiquark and that the former has a sharp jump at a critical energy density whereas the latter transits smoothly from the low to the high energy density domains. We interpret this as a quantitative difference in the production of baryons and mesons with energy density. We use this approach to compute the proton and pion spectra in a Bjorken scenario that incorporates the evolution of these probabilities with energy density, and therefore with proper time. From the spectra, we compute the proton to pion ratio and compare to data at the highest RHIC energies. We show that for a standard choice of parameters, this ratio reaches one, though the maximum is very sensitive to the initial evolution proper time.Comment: 10 pages, 12 figures, version to appear in Phys. Rev.

Análisis del ciclo de vida de un edificio con estructura de madera contralaminada en Granada-España

A residential building with cross-laminated timber structure in Granada (Spain) was analyzed using the life cycle assessment methodology, life cycle energy analysis and sensitivity analysis to changes in efficiency of operating energy, materials database, transport distances and different scenarios for C&DW. The environmental impacts of the materials and construction production and embedded energy were relatively significant. The global warming impact category was very low due to the CO2 sequestration of wooden materials. Sensitivity analysis revealed that the most significant reduction in environmental impact was achieved through improvements in energy efficiency, high uncertainty in the impacts of the environmental product declaration, the low effect of long-distance transport on the overall impact and the feasibility of the objective of recovery of the Waste Framework Directive by 2020 (above 70%).Se ha estudiado un edificio residencial con estructura de madera laminada en Granada (España) con la metodología de análisis del ciclo de vida, análisis energético del ciclo de vida y análisis de sensibilidad a cambios en la eficiencia energética durante el uso, bases de datos, distancia del transporte y diferentes escenarios para los residuos. Los impactos ambientales de las etapas de producción de materiales y construcción, así como la energía embebida fueron relativamente significantes. El valor del calentamiento global ha sido muy bajo debido al secuestro de CO2 por la madera. El análisis de sensibilidad ha revelado que la mayor reducción se consigue con la mejora de la eficiencia energética, la alta incertidumbre en los impactos de las declaraciones ambientales de producto, el escaso efecto del transporte de larga distancia sobre los impactos totales y la viabilidad de conseguir el objetivo de valorización de la Directiva Marco para el horizonte 2020 (mayor del 70%).This research has been funded by the research contract: “Riesgo y sostenibilidad en los proyectos de ingeniería y edificación” (Fundación Universidad de Granada – UCOP Construcciones, SA, contract No. 3418-00). Construction Project & Site Data have been provided by Bonsai Arquitectos (Mr. Llopis) and Invesia Corporación

Experimental determination of the absorption strength in absorbing chaotic cavities

Due to the experimental necessity we present a formula to determine the absorption strength by power losses inside a chaotic system (cavities, graphs, acoustic resonators, etc) when the antenna coupling, always present in experimental measurements, is taken into account. This is done by calculating the average of the absorption coefficient as a function of the absorption strength and the coupling of the antenna to the system, in the one channel case.Comment: 6 pages, 3 figures, Submitted to Phys. Rev.

Distribution of the S-matrix in chaotic microwave cavities with direct processes and absorption

We quantify the presence of direct processes in the S-matrix of chaotic microwave cavities with absorption in the one-channel case. To this end the full distribution P_S(S) of the S-matrix, i.e. S=\sqrt{R}e^{i\theta}, is studied in cavities with time-reversal symmetry for different antenna coupling strengths T_a or direct processes. The experimental results are compared with random-matrix calculations and with numerical simulations based on the Heidelberg approach including absorption. The theoretical result is a generalization of the Poisson kernel. The experimental and the numerical distributions are in excellent agreement with random-matrix predictions for all cases.Comment: 4 pages, 4 figure