Analysis of Deeply Virtual Compton Scattering Data at Jefferson Lab and Proton Tomography

The CLAS and Hall A collaborations at Jefferson Laboratory have recently released new results for the ep->ep{\gamma} reaction. We analyze these new data within the Generalized Parton Distribution formalism. Employing a fitter algorithm introduced and used in earlier works, we are able to extract from these data new constraints on the kinematical dependence of three Compton Form Factors. Based on experimental data, we subsequently extract the dependence of the proton charge radius on the quarks longitudinal momentum fraction.Comment: 25 pages, 26 figure

A TMD-based model for Hadronization off heavy nuclei

Semi-inclusive deep inelastic scattering (SIDIS) off nuclei is a unique process to study the parton propagation mechanism and its modification induced by the presence of the nuclear medium. It allows us to probe the medium properties, particularly the cold nuclear matter transport coefficient, which can be directly linked to the nuclear gluon density. We present here a model for hadron production in deep inelastic lepton-nucleus scattering, which takes into account the hadronic transverse momentum of final state particles via transverse-momentum dependent (TMD) parton distributions and fragmentation functions. We implement parton energy loss and hadronic absorption with a geometrical model of the nucleus. The model is compared with the nuclear SIDIS multiplicity ratios and transverse-momentum broadening data from the CLAS, HERMES, and EMC collaborations, aiming for a simultaneous description of these data sets. We obtain a good agreement over the various nuclear targets and the wide kinematical range of those experiments. We best describe the data with a transport coefficient \hat q = 0.3 GeV/fm 2 , and we highlight the importance and the role of correlations in extracting this quantity.Comment: 22 pages, 8 figure

Dewetting of thin polymer films near the glass transition

Dewetting of ultra-thin polymer films near the glass transition exhibits unexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)]. We present here the first theoretical attempt to understand these features, focusing on the shear-thinning behaviour of these films. We analyse the profile of the dewetting film, and characterize the time evolution of the dry region radius, $R_{d}(t)$, and of the rim height, $h_{m}(t)$. After a transient time depending on the initial thickness, $h_{m}(t)$ grows like $\sqrt{t}$ while $R_{d}(t)$ increases like $\exp{(\sqrt{t})}$. Different regimes of growth are expected, depending on the initial film thickness and experimental time range.Comment: 4 pages, 5 figures Revised version, published in Physical Review Letters: F. Saulnier, E. Raphael and P.-G. de Gennes, Phys. Rev. Lett. 88, 196101 (2002

Global electricity network - Feasibility study

With the strong development of renewable energy sources worldwide, the concept of a global electricity network has been imagined in order to take advantage of the diversity from different time zones, seasons, load patterns and the intermittency of the generation, thus supporting a balanced coordination of power supply of all interconnected countries. The TB presents the results of the feasibility study performed by WG C1.35. It addresses the challenges, benefits and issues of uneven distribution of energy resources across the world. The time horizon selected is 2050. The study finds significant potential benefits of a global interconnection, identifies the most promising links, and includes sensitivity analyses to different factors, such as wind energy capacity factors or technology costs

Fragmentation des Quarks et Formation des Hadrons dans la Matière Nucléaire

La formation des hadrons est, dans le cadre de la théorie quantique de couleur (QCD), un processus non-perturbatif ; cette caractéristique entraîne d’importantes difficultés théoriques. C’est pourquoi, les mesures expérimentales de fragmentation dans différents noyaux sont une nécessité afin d’obtenir des progrès tangibles dans la compréhension des mécanismes de formation des hadrons. La thèse commence par les bases théoriques nécessaires à une telle approche, suivies des principaux modèles qui lui sont associés.La thèse se poursuit par l’analyse de données de Jefferson Lab obtenues à l’aide d’un faisceau d’électrons de 5 GeV incident sur différentes cibles (2H, C, Al, Fe, Sn et Pb). Les produits de la réaction sont mesurés avec le spectromètre CLAS. Les principaux résultats de cette expérience sont : (a) l’analyse multi-dimensionnelle des observables mesurées, qui permet une meilleure confrontation avec les modèles théoriques et l’extraction d’informations temporelles sur la fragmentation, et (b) l’observation d’une atténuation hadronique non-linéaire en fonction du rayon du noyau cible. Dans une partie plus théorique, le générateur d’événements PyQM, développé dans le but de reproduire les données de la collaboration HERMES, est présenté. Les résultats sont mitigés, en effet la base théorique utilisée ne semble pas s’appliquer au cas étudié, néanmoins certaines caractéristiques des données sont reproduites permettant de comprendre leurs origines parfois inattendues. Enfin, les possibilités d’expériences futures, à Jefferson Lab et dans un collisionneur ion-électron (EIC), sont explorées.The hadron formation is, in the framework of the quantum chromodynamics theory (QCD), a non-perturbative process; this characteristic leads to important theoretical challenges. This is why experimental measurements of fragmentation in nuclei are a necessity in order to obtain substantial progress in our understanding of the mechanisms of hadron formation. The thesis begins with the introduction of theoretical background, followed by an overview of theoretical models. The thesis continues with the analysis of Jefferson Lab data obtained with a 5 GeV electron beam incident on various targets (2H, C, Al, Fe, Sn and Pb). The reaction products are measured with the CLAS spectrometer of Hall B. The main results are: (a) a multi-dimensional analysis of the measured observables, which permits a better confrontation with theoretical models and the extraction of temporal information on fragmentation, and (b) the observation of a non linear hadronic attenuation as a function of the target’s nuclear radius. The PyQM event generator, developed to reproduce the data from the HERMES collaboration, is also presented. The results are ambivalent, the theoretical basis used does not seem to apply to the studied case, however, some characteristics of the data are reproduced allowing to understand their origin, which is sometimes unexpected. Finally, the possibilities for future experiments, at Jefferson Lab and at an Electron-Ion Collider (EIC), are explored

Fragmentation des Quarks et Formation des Hadrons dans la Matière Nucléaire

The hadron formation is, in the framework of the quantum chromodynamics theory (QCD), a non-perturbative process; this characteristic leads to important theoretical challenges. This is why experimental measurements of fragmentation in nuclei are a necessity in order to obtain substantial progress in our understanding of the mechanisms of hadron formation. The thesis begins with the introduction of theoretical background, followed by an overview of theoretical models. The thesis continues with the analysis of Jefferson Lab data obtained with a 5 GeV electron beam incident on various targets ($^2$H, C, Al, Fe, Sn and Pb).The reaction products are measured with the CLAS spectrometer of Hall B. The main results are: (a) multi-dimensional analysis of the measured observables, which permits a better confrontation with theoretical models and the extraction of temporal information on fragmentation, and (b) the observation of a non linear hadronic attenuation as a function of the target's nuclear radius. The PyQM event generator, developed to reproduce the data from the HERMES collaboration, is also presented. The results are ambivalent, the theoretical basis used does not seem to apply to the studied case, however, some characteristics of the data are reproduced allowing to understand their origin, which is sometimes unexpected. Finally, the possibilities for future experiments, at Jefferson Lab and at an Electron-Ion Collider (EIC), are explored.La formation des hadrons est, dans le cadre de la théorie quantique de couleur (QCD), un processus non-perturbatif ; cette caractéristique entraîne d'importantes difficultés théoriques. C'est pourquoi, les mesures expérimentales de fragmentation dans différents noyaux sont une nécessité afin d'obtenir des progrès tangibles dans la compréhension des mécanismes de formation des hadrons. La thèse commence par les bases théoriques nécessaires à une telle approche, suivies des principaux modèles qui lui sont associés. La thèse se poursuit par l'analyse de données de Jefferson Lab obtenues à l'aide d'un faisceau d'électrons de 5 GeV incident sur différentes cibles ($^2$H, C, Al, Fe, Sn et Pb). Les produits de la réaction sont mesurés avec le spectromètre CLAS. Les principaux résultats de cette expérience sont : (a) l'analyse multidimensionnelle des observables mesurées, qui permet une meilleure confrontation avec les modèles théoriques et l'extraction d'informations temporelles sur la fragmentation, et (b) l'observation d'une atténuation hadronique non-linéaire en fonction du rayon du noyau cible. Dans une partie plus théorique, le générateur d'événements PyQM, développé dans le but de reproduire les données de la collaboration HERMES, est présenté. Les résultats sont mitigés, en effet la base théorique utilisée ne semble pas s'appliquer au cas étudié, néanmoins certaines caractéristiques des données sont reproduites permettant de comprendre leurs origines parfois inattendues. Enfin, les possibilités d'expériences futures, à Jefferson Lab et dans un collisionneur ion-électron (EIC), sont explorées

A TMD-based model for Hadronization off heavy nuclei

International audienceSemi-inclusive deep inelastic scattering (SIDIS) off nuclei is a unique process to study the parton propagation mechanism and its modification induced by the presence of the nuclear medium. It allows us to probe the medium properties, particularly the cold nuclear matter transport coefficient, which can be directly linked to the nuclear gluon density. We present here a model for hadron production in deep inelastic lepton-nucleus scattering, which takes into account the hadronic transverse momentum of final state particles via transverse-momentum dependent (TMD) parton distributions and fragmentation functions. We implement parton energy loss and hadronic absorption with a geometrical model of the nucleus. The model is compared with the nuclear SIDIS multiplicity ratios and transverse-momentum broadening data from the CLAS, HERMES, and EMC collaborations, aiming for a simultaneous description of these data sets. We obtain a good agreement over the various nuclear targets and the wide kinematical range of those experiments. We best describe the data with a transport coefficient q̂ = 0.3 GeV/fm 2 , and we highlight the importance and the role of correlations in extracting this quantity

Unraveling light nuclei with deeply virtual Compton scattering processes: from models to event generation

International audienceIn this talk, we present the analysis of a deeply virtual Compton scattering process off 4 He. This study is done within the impulse approximation approach including state-of-the-art models for the nucleonic and nuclear ingredients. A glimpse on the comparison between our results and the experimental data coming form Jefferson Lab is also given. The last part of this work is devoted to the description of the new Monte Carlo event generator based on the models presented in the main part of the talk. First results from the simulations performed at the kinematic conditions foreseen at the Electron Ion Collider are discussed demonstrating that there is a wide enough kinematical range to reach the tomography of 4 He and understand other possible aspects of the elusive nuclear parton dynamics

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