Microscopic theory of absorption and emission in nanostructured solar cells: Beyond the generalized Planck formula

Absorption and emission in inorganic bipolar solar cells based on low dimensional structures exhibiting the effects of quantum confinement is investigated in the framework of a comprehensive microscopic theory of the optical and electronic degrees of freedom of the photovoltaic system. In a quantum-statistical treatment based on non-equilibrium Green's functions, the optical transition rates are related to the conservation of electronic currents, providing a quantum version of the balance equations describing the operation of a photovoltaic device. The generalized Planck law used for the determination of emission from an excited semiconductor in quasi-equilibrium is replaced by an expression of extended validity, where no assumptions on the distribution of electrons and photons are made. The theory is illustrated by the numerical simulation of single quantum well diodes at the radiative limit.Comment: 6 pages, 5 figures, extended LaTeX version of the EUPVSEC09 proceedings articl

On the influence of the cosmological constant on gravitational lensing in small systems

The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Due to Lambda the unresolved images are slightly demagnified, the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible for near lenses. In the case of null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation, references added, results unchanged, in press on PR

Unregulated Desires: Anomie, the “Rainbow Underclass” and Second-generation Alevi Kurdish Gangs in London

This article offers a case study of the adaptation strategies of a section of second-generation young male Alevi Kurds in London and the social conditions which make some of them more prone to join gangs and to reject mainstream institutions in their search for instant material rewards. It is instructive to use Durkheim’s analysis of society’s integrative and regulative functions and particularly his concept of anomie to understand a situation where the legitimate means in the pursuit of material wealth and comfort are out of balance with the demand, calling into question the legitimacy of the institutions which provide these functions. Those who cannot compete through existing institutions are more likely to seek alternative means to achieve these ends. Durkheim identified youth as more vulnerable to such unregulated desires and I argue that his approach offers valuable insights into the anomic pressures confronting second-generation migrant young men in particular

N=2 supersymmetric extension of l-conformal Galilei algebra

N=2 supersymmetric extension of the l-conformal Galilei algebra is constructed. A relation between its representations in flat spacetime and in Newton-Hooke spacetime is discussed. An infinite-dimensional generalization of the superalgebra is given.Comment: V4: 8 pages, references and acknowledgements adde

Measuring the W Boson Mass at Hadron Colliders

We discuss the prospects for measuring the W mass in Run II of the Tevatron and at the LHC. The basic techniques used to measure M_W are described and the statistical, theoretical and detector-related uncertainties are discussed in detail.Comment: Latex, 13 pages, 6 figures, 1 table, invited talk presented at the Mini-Workshop ``Electroweak Precision Data and the Higgs Mass'', DESY Zeuthen, Germany, February 28 - March 1, 2003, to appear in the Proceeding

Interpreting Quantum Chromodynamics from Spin Glass- and Polymer Analogies

In an informal way some kind of Ising Lattice QCD is introduced which allows to interprete and discuss the well-known theory of quantum chromodynamics (confinement, quarks and gluons, etc.) from simple phenomena of magnetism and polymer physics. Also the viewpoint of duality is stressed. Moreover, the non-abelian character of the Lie group SU(3) is important. The essential arguments for confinement and asymptotic freedom are given at the very end of the manuscript, after an appendix.Comment: 6 pages; 0 figures, the main arguments are given at the end of an appendi

Physics at ELSA, achievements and future

At ELSA interesting results on baryon resonances have been obtained by the CB-ELSA, the CBELSA/TAPS and the SAPHIR collaborations. New resonances were found, in particular a new $\rm D_{15}(2070)$ decaying into $p\eta$, was recently observed by the CB-ELSA experiment. The availability of a polarized beam and a polarized target did allow to measure the GDH sum rule up to 2.9 GeV. In the future double polarization experiments will be performed using the Crystal Barrel detector together with new forward detector components. These polarization observables will provide important additional information for the partial wave analyses performed to extract the contributing resonances and their parameters from the data.Comment: Prepared for the MENU 2004 conference proceedings, 7 pages, 6 eps-figure