Search for W′→tbˉW'\rightarrow t\bar{b} in the lepton plus jets final states with the ATLAS detector at the LHC

This document presents a search for a $W'$ boson, decaying to a top quark and a $b$ quark in an effective coupling approach, using a multivariate method based on boosted decision trees. It reports exclusion limits on the $W'\rightarrow tb$ cross-section times branching ratio and effective couplings as a function of the $W'$-boson mass. The search covers $W'$-boson masses between 0.5 and 3.0 TeV, for right-handed or left-handed $W'$-boson, with 20.3 fb$^{-1}$ of proton-proton collision data produced by the LHC in 2012, at a center-of-mass energy of 8 TeV and collected by the ATLAS detector.Comment: TOP2014, 4 pages, 4 figure

Cross-layer framework and optimization for efficient use of the energy budget of IoT Nodes

Both physical and MAC-layer need to be jointly optimized to maximize the autonomy of IoT devices. Therefore, a cross-layer design is imperative to effectively realize Low Power Wide Area networks (LPWANs). In the present paper, a cross-layer assessment framework including power modeling is proposed. Through this simulation framework, the energy consumption of IoT devices, currently deployed in LoRaWAN networks, is evaluated. We demonstrate that a cross-layer approach significantly improves energy efficiency and overall throughput. Two major contributions are made. First, an open-source LPWAN assessment framework has been conceived. It allows testing and evaluating hypotheses and schemes. Secondly, as a representative case, the LoRaWAN protocol is assessed. The findings indicate how a cross-layer approach can optimize LPWANs in terms of energy efficiency and throughput. For instance, it is shown that the use of larger payloads can reduce up to three times the energy consumption on quasi-static channels yet may bring an energy penalty under adverse dynamic conditions

Drivers' decision-making when attempting to cross an intersection results from choice between affordances

International audienceIn theory, a safe approach to an intersection implies that drivers can simultaneously manage two scenarios: they either choose to cross or to give way to an oncoming vehicle. In this article we formalize the critical time for safe crossing (CT cross) and the critical time for safe stopping (CT stop) to represent crossing and stopping possibilities, respectively. We describe these critical times in terms of affordances and empirically test their respective contribution to the driver's decision-making process. Using a driving simulator, three groups of participants drove cars with identical acceleration capabilities and different braking capabilities. They were asked to try to cross an intersection where there was an oncoming vehicle, if they deemed the maneuver to be safe. If not, they could decide to stop or, as a last resort, make an emergency exit. The intersections were identical among groups. Results showed that although the crossing possibilities (CT cross) were the same for all groups, there were between-group differences in crossing frequency. This suggests that stopping possibilities (CT stop) play a role in the driver's decision-making process, in addition to the crossing possibilities. These results can be accounted for by a behavioral model of decision making, and provide support for the hypothesis of choice between affordances

Recherche de résonances W' → tb dans le canal lepton plus jets avec le détecteur ATLAS au LHC

The research work carried out during this Ph.D thesis has been performed in the context of the ATLAS experiment, one of the four major LHC experiments, and was primarily dedicated to the search for a new chaged heavy gauge boson, called W' and predicted by many extensions of the Standard Model of particle physics. This manuscript presents a search for W' boson decaying into a top and a bottom quark through an effective coupling approach, in the lepton plus jets final states. This search is performed with 20.3 fb−1 of proton-proton collision data, produced by the LHC with a center-of-mass energy of 8 TeV and collected by the ATLAS detector in 2012. Several scenarios are considered where the W boson can couple to left-handed (W'L) or right-handed (W'R) fermions. A multivariate techniques based on boosted decision trees is used to search for an excess of W signal process in the recorded data. No excess is observed beyond the experimental uncertainties for the data analysed so far. A statistical analysis is performed in order to extract exclusion limits on the mass and the production cross section of the particle. Masses below 1.92, 1.80 and 1.70 TeV are excluded, respectively for W'R and W'L bosons taking into account or not interference effects. These exclusion limits on the production cross section are also reinterpreted in terms of exclusion limits on the effective coupling g'/g of the particle. The lowest exclusion limits observed on the ratio g'/g are equal to 0.20 and 0.16, respectively, for W'R and W'L searches, and are obtained for a W'R/L mass of 0.75 TeV. A search for charged Higgs boson decaying into a top and a bottom quark is presented in this manuscript. This search is based on an effective coupling approach describing a type II Two Doublet Higgs Model. It reuses the analysis infrastructure developed for the W' search and is completed by phenomenological studies related to the production cross section calculation for the process and the characterisation of the resonance width effects affecting the analysis. Preliminary results on the excluded cross section limits pp → H+→ tb show that the analysis is not able to exclude a signal a H+ boson for all theoretical scenarios considered, due to low production cross sections predicted. In parallel of these activities, several developments have been performed on the fast simulation of the ATLAS calorimeter system in order to overcome its limitations. In particular, a new parametrisation and fast simulation model for the energy response of the calorimeter is presented in this manuscript. This model, still under development, shows encouraging results for simulated single pion event and allows to reduce considerably the memory footprint of the parametrisation compared to previous versions of FastCaloSim, while enabling future reparametrisations to be faster and automated.Le travail de recherche réalisé au cours de cette thèse s’inscrit dans le contexte de l’expérience ATLAS, l’une des quatre grandes expériences auprès du collisionneur LHC. Il fut principalement dédié à la recherche de nouveaux bosons de jauge lourds chargés, appelé W' et prédits par de nombreuses extensions du Modèle Standard de la physique des particules. Ce manuscrit présente une recherche du boson W' se désintégrant en un quark top et un quark beau à travers une approche de couplage effectif, dans des états finals de désintégrations leptoniques du quark top. Cette recherche fut réalisée avec 20.3 fb−1 de données de collision proton-proton, produits par le LHC à une énergie dans le centre de masse de 8 TeV et collectées par le détecteur ATLAS en 2012. Plusieurs scénarios d’études sont envisagés où le boson W' se couple soit à des fermions de chiralité gauche (W'L) soit de chiralité droite (W'R). Une technique d’analyse multivariée utilisant des arbres de décision boostés (BDT) est utilisée afin de mettre évidence un excès de processus de signal dans les données enregistrées. Aucun excès n’est observé au-delà des incertitudes expérimentales pour la statistique de données analysées jusque-là. Une analyse statistique est réalisée afin d’extraire des limites d’exclusion sur la masse et la section efficace de production de la particule. Des masses inférieures à 1.92, 1.80 et 1.70 TeV furent exclues respectivement pour des bosons W'R et W'L, en tenant compte ou non d’effets d’interférence. Les limites d’exclusion sur les sections efficaces de production sont réinterprétées en matière de limite d’exclusion sur le couplage effectif g'/g de la particule. Les limites d’exclusion les plus basses observées sur le rapport g'/g, respectivement de 0.20 et 0.16 pour les recherches de bosons W'R et W'L, furent obtenues pour une masse de boson W'R/L de 0.75 TeV. Une recherche de bosons de Higgs chargés se désintégrant en un quark top et un quark beau est également présentée dans ce manuscrit. Cette dernière repose sur une approche de couplage effectif décrivant un modèle à deux doublets de Higgs de type II. Cette analyse réutilise l’infrastructure développée pour la recherche du boson W' est complétée d’études phénoménologiques liées au calcul de la section efficace de ce processus ainsi que sur la caractérisation des effets de largeur de la résonance recherchée. Les premiers résultats obtenus sur la limite d’exclusion sur la section efficace de production pp → H+→ tb montrent toutefois que cette analyse ne semble pas être en mesure d’exclure un signal de boson H+ pour l’ensemble des scénarios théoriques considérés, compte tenu des faibles sections efficaces de production prédites. En parallèle de ces activités, des développements ont été réalisés pour la simulation rapide du système de calorimétrie FastCaloSim du détecteur ATLAS afin de pallier ses limitations. En particulier, un nouveau modèle de paramétrisation et de simulation rapide de la réponse en énergie du système de calorimétrie est présenté dans ce manuscrit. Ce modèle, toujours en développement, montre des résultats très encourageant pour la simulation d’événements à pion unique et permet de réduire considérablement l’empreinte mémoire de la paramétrisation en comparaison avec des versions précédentes de FastCaloSim, tout en permettant aux futures reparamétrisations d’être plus rapides et automatisées

Les destins divergents des régionalismes flamands et francophones : une perspective historique

Les tensions entre francophones et néerlandophones tournant autour d'une régionalisation de compétences fédérales ne sont pas nouvelles et s'inscrivent dans un lent processus de poussée régionaliste émanant aussi bien du sud que du nord du pays depuis près d'un siècle. Nous reviendrons dans cet article sur l'histoire politique et électorale du régionalisme en Belgique. Nous montrerons comment des poussées régionalistes régulières ont transformé l’État belge unitaire en un État décentralisé dans lequel le fédéral a perdu peu à peu ses prérogatives. L’hypothèse principale qui sous-tend cet article est que les partis régionalistes ont connu des succès électoraux temporaires (1919-21, 1936, 1965-77, 2009- ?), suivis de déclins dès que les revendications régionalistes des opinions étaient satisfaites. La vague suivante repose alors sur un approfondissement des revendications régionalistes. Dans ce cadre, nous insisterons en particulier sur le soutien croissant des partis régionalistes au nord du pays contrastant avec l'absence de parti régionaliste wallon depuis le milieu des années 1980. Nous montrons enfin que les vagues régionalistes successives reposent sur des géographies à chaque fois renouvelées, à l’exception notable du rôle d’Anvers au sein du mouvement flamand.The tensions between French-speaking and Dutch-speaking communities in Belgium about the regionalization of federal competences are not new and have to be understood in the long history of regionalism. This article tells the history and the geography of regional waves in Belgium. We will in particular show how these successive regionalist fevers have progressively reshaped the Belgian Central State into a federal State where regions gain in competences over the time. The main hypothesis is that regionalist parties have gone through temporary electoral successes (1919-21, 1936, 1965-77, 2009-?), followed by long period of decline as soon as the regionalist claims of the opinion were satisfied. The next wave of regionalism relies thus on the new claims to deepen the regionalisation of the Belgian State. In this framework, we will insist on the growing support for regionalist parties in the Flemish part of the country since the eighties, in contrast with the quasi absence of Walloon regionalist parties in the recent years. We also show that the geography of regionalist parties have considerably evolved over the time, with the exception of Antwerp which has remained at the heart of most Flemish regionalist parties

Cinema as mnemotechnics

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Housing land transaction data and structural econometric estimation of preference parameters for urban economic simulation models

This paper describes a dataset of 6284 land transactions prices and plot surfaces in 3 medium-sized cities in France (Besançon, Dijon and Brest). The dataset includes road accessibility as obtained from a minimization algorithm, and the amount of green space available to households in the neighborhood of the transactions, as evaluated from a land cover dataset. Further to the data presentation, the paper describes how these variables can be used to estimate the non-observable parameters of a residential choice function explicitly derived from a microeconomic model. The estimates are used by Caruso et al. (2015) to run a calibrated microeconomic urban growth simulation model where households are assumed to trade-off accessibility and local green space amenities

Maize terpene synthase 1 impacts insect behavior via the production of monoterpene volatiles \u3ci\u3eβ\u3c/i\u3e-myrcene and linalool

Plant-derived volatiles are important mediators of plant-insect interactions as they can provide cues for host location and quality, or act as direct or indirect defense molecules. The volatiles produced by Zea mays (maize) include a range of terpenes, likely produced by several of the terpene synthases (TPS) present in maize. Determining the roles of specific terpene volatiles and individual TPSs in maize-insect interactions is challenging due to the promiscuous nature of TPSs in vitro and their potential for functional redundancy. In this study, we used metabolite GWAS of a sweetcorn diversity panel infested with Spodoptera frugiperda (fall armyworm) to identify genetic correlations between TPSs and individual volatiles. This analysis revealed a correlation between maize terpene synthase 1 (ZmTPS1) and emission of the monoterpene volatiles linalool and β-myrcene. Electroantennogram assays showed gravid S. frugiperda could detect both linalool and β-myrcene. Quantification of headspace volatiles in a maize tps1 loss-of-function mutant confirmed that ZmTPS1 is an important contributor to linalool and β-myrcene emission in maize. Furthermore, pairwise choice assays between tps1 mutant and wildtype plants showed that ZmTPS1, and by extension its volatile products, aid host location in the chewing insect S. frugiperda, yet repel the sap-sucking pest, Rhopalosiphum maidis (corn leaf aphid). On the other hand, ZmTPS1 had no impact on indirect defense via the recruitment of the parasitoid Cotesia marginiventris. ZmTPS1 is therefore an important mediator of the interactions between maize and its insect pests