Test of the τ-model of Bose–Einstein correlations and reconstruction of the source function in hadronic Z-boson decay at LEP

Bose–Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various parametrizations. A good description is achieved using a Lévy stable distribution in conjunction with a model where a particle’s momentum is correlated with its space–time point of production, the τ-model. Using this description and the measured rapidity and transverse momentum distributions, the space–time evolution of particle emission in two-jet events is reconstructed. However, the elongation of the particle emission region previously observed is not accommodated in the τ-model, and this is investigated using an ad hoc modification

Détection et Reconnaissance des Gestes Emblématiques

Session "Atelier IHMA"National audienceDans cette contribution, nous présentons un système de reconnaissance en ligne de gestes emblématiques et son utilisation pour le contrôle d'un robot mobile. Ce système comporte quatre sous-systèmes : un premier qui permet de détecter la personne et d'extraire les mouvements de la partie supérieure de cette personne. Un second, permet d'isoler les mouvements, une troisième permet de reconnaître un des mouvements appris a priori. Enfin le dernier module, traduit les mouvements reconnus en termes de contrôle d'un robot mobile à roues. Dans notre approche, nous avons surtout traité du problème de la généralisation : faire l'apprentissage sur une base réduite de personnes et utiliser cette connaissance pour reconnaître n'importe quelle personne, indépendamment de sa morphologie, de son âge, de son sexe et de son positionnement par rapport au capteur. Nous détaillons les résultats obtenus pour la reconnaissance ainsi que l'utilisation du système dans des scenarios de contrôle d'un robot

Forward-backward multiplicity correlations and leakage parameter behaviour in asymmetric high energy collisions

Continuing previous work, forward-backward multiplicity correlations are studied in asymmetric collisions in the framework of the weighted superposition mechanism of different classes of events. New parameters for the asymmetric clan distribution and for the particle leakage from clans in one hemisphere to the opposite one are introduced to effectively classify different classes of collisions. This tool should be used to explore forward-backward multiplicity correlations in AB and pA collisions in present and future experiments at RHIC and LHC.Comment: 14 pages, 2 figures, latex 2e with amsmat

R^2 Dark Matter

There is a non-trivial four-derivative extension of the gravitational spectrum that is free of ghosts and phenomenologically viable. It is the so called $R^2$-gravity since it is defined by the only addition of a term proportional to the square of the scalar curvature. Just the presence of this term does not improve the ultraviolet behaviour of Einstein gravity but introduces one additional scalar degree of freedom that can account for the dark matter of our Universe.Comment: 6 pages, 1 figure, to appear in the Proceedings of the sixth International Workshop on the Dark Side of the Universe (DSU2010) Leon, Guanajuato, Mexico 1-6 June 201

Ruthenium(II) and Iridium(III) complexes featuring NHC-Sulfonate chelate

International audienc

The use of cosmic muons in detecting heterogeneities in large volumes

The muon intensity attenuation method to detect heterogeneities in large matter volumes is analyzed. Approximate analytical expressions to estimate the collection time and the signal to noise ratio, are proposed and validated by Monte Carlo simulations. Important parameters, including point spread function and coordinate reconstruction uncertainty are also estimated using Monte Carlo simulations.Comment: 8 pages, 11 figures, submetted to NIM

A long-term perspective on deforestation rates in the Brazilian Amazon

Monitoring tropical forest cover is central to biodiversity preservation, terrestrial carbon stocks, essential ecosystem and climate functions, and ultimately, sustainable economic development. The Amazon forest is the Earth’s largest rainforest, and despite intensive studies on current deforestation rates, relatively little is known as to how these compare to historic (pre 1985) deforestation rates. We quantified land cover change between 1975 and 2014 in the so-called Arc of Deforestation of the Brazilian Amazon, covering the southern stretch of the Amazon forest and part of the Cerrado biome. We applied a consistent method that made use of data from Landsat sensors: Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI). We acquired suitable images from the US Geological Survey (USGS) for five epochs: 1975, 1990, 2000, 2010, and 2014. We then performed land cover analysis for each epoch using a systematic sample of 156 sites, each one covering 10 km × 10 km, located at the confluence point of integer degree latitudes and longitudes. An object-based classification of the images was performed with five land cover classes: tree cover, tree cover mosaic, other wooded land, other land cover, and water. The automatic classification results were corrected by visual interpretation, and, when available, by comparison with higher resolution imagery. Our results show a decrease of forest cover of 24.2% in the last 40 years in the Brazilian Arc of Deforestation, with an average yearly net forest cover change rate of -0.71% for the 39 years considered

Flavour structure of low-energy hadron pair photoproduction

We consider the process $\gamma\gamma\to H_1\bar H_2$ where $H_1$ and $H_2$ are either mesons or baryons. The experimental findings for such quantities as the $p\bar p$ and $K_SK_S$ differential cross sections, in the energy range currently probed, are found often to be in disparity with the scaling behaviour expected from hard constituent scattering. We discuss the long-distance pole--resonance contribution in understanding the origin of these phenomena, as well as the amplitude relations governing the short-distance contribution which we model as a scaling contribution. When considering the latter, we argue that the difference found for the $K_SK_S$ and the $K^+K^-$ integrated cross sections can be attributed to the s-channel isovector component. This corresponds to the $\rho\omega\to a$ subprocess in the VMD (vector-meson-dominance) language. The ratio of the two cross sections is enhanced by the suppression of the $\phi$ component, and is hence constrained. We give similar constraints to a number of other hadron pair production channels. After writing down the scaling and pole--resonance contributions accordingly, the direct summation of the two contributions is found to reproduce some salient features of the $p\bar p$ and $K^+K^-$ data.Comment: 12 pages, 9 figures, revised version to be published in EPJ