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Deeply Virtual Compton Scattering And Generalized Parton Distributions At Clas
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Book Synopsis Deeply Virtual Compton Scattering and Generalized Parton Distributions at CLAS. by :
Download or read book Deeply Virtual Compton Scattering and Generalized Parton Distributions at CLAS. written by and published by . This book was released on 2008 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The exclusive electroproduction of real photons and mesons at high momentum transfer allows us to access the Generalized Parton Distributions (GPDs). The formalism of the GPDs provides a unified description of the hadronic structure in terms of quark and gluonic degrees of freedom. In particular, the Deeply Virtual Compton Scattering (DVCS), ep â e2p2Å, is one of the key reactions to determine the GPDs experimentally, as it is the simplest process that can be described in terms of GPDs. A dedicated experiment to study DVCS has been carried out in Hall B at Jefferson Lab. Beam-spin asymmetries, resulting from the interference of the Bethe-Heitler process and DVCS have been extracted over the widest kinematic range ever accessed for this reaction (1.2
Book Synopsis Generalized Parton Distributions And Deeply Virtual Compton Scattering At Clas by :
Download or read book Generalized Parton Distributions And Deeply Virtual Compton Scattering At Clas written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deeply virtual Compton scattering is the simplest process to access the generalized parton distributions of the nucleon. A dedicated large statistics experiment for the measurement of deeply virtual Compton scattering with a 6 GeV polarized electron beam on a proton target has been performed at the Hall-B of Jefferson Laboratory with the CLAS spectrometer. The experiment covered a wide kinematic range, allowing the study of the beam spin asymmetry as function of the Bjorken variable xB, the Mandelstam variable t, the virtual photon four-momentum squared Q2 and the angle phi between leptonic and hadronic planes. The preliminary results are in agreement with previous measurements and with the predicted twist-2 dominance.
Book Synopsis Generalized Parton Distributions and Deeply Virtual Compton Scattering on Proton at CLAS. by :
Download or read book Generalized Parton Distributions and Deeply Virtual Compton Scattering on Proton at CLAS. written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two measurements of target and beam spin asymmetries for the reaction ep→ep[gamma] were performed with CLAS at Jefferson Laboratory. Polarized 5.7 GeV electrons were impinging on a longitudinally polarized ammonia and liquid hydrogen target respectively. These measurements are sensitive to Generalized Parton Distributions. Sizable sin phi azimuthal angular dependences were observed in both experiments, indicating the dominance of leading twist terms and the possibility of extracting combinations of Generalized Parton Distributions on the nucleon.
Book Synopsis Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the Nucleon with the CLAS and CLAS12 Detectors at the Jefferson Laboratory by : Baptiste Guegan
Download or read book Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the Nucleon with the CLAS and CLAS12 Detectors at the Jefferson Laboratory written by Baptiste Guegan and published by . This book was released on 2012 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the Nucleon with the CLAS and CLAS12 Detectors at the Jefferson Laboratory by :
Download or read book Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the Nucleon with the CLAS and CLAS12 Detectors at the Jefferson Laboratory written by and published by . This book was released on 2012 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN 2!lN[gamma], and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.
Book Synopsis Deeply Virtual Compton Scattering Cross Section Measured with CLAS. by :
Download or read book Deeply Virtual Compton Scattering Cross Section Measured with CLAS. written by and published by . This book was released on 2014 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Generalized Parton Distributions (GPDs) provide a new description of nucleon structure in terms of its elementary constituents, the quarks and the gluons. Including and extending the information provided by the form factors and the parton distribution functions, they describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark in the nucleon eN --> e'N'g, is the exclusive process most directly interpretable in terms of GPDs. A dedicated experiment to study DVCS with the CLAS detector at Jefferson Lab has been carried out using a 5.9-GeV polarized electron beam and an unpolarized hydrogen target, allowing us to collect DVCS events in the widest kinematic range ever explored in the valence region : 1.0
Book Synopsis Deeply Virtual Compton Scattering with CLAS. by :
Download or read book Deeply Virtual Compton Scattering with CLAS. written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The beam spin asymmetries of the reaction ep -> epg in the Bjorken regime were measured over a wide kinematical domain using the CLAS detector and a new lead-tungstate calorimeter. Through the interference of the Bethe-Heitler process with Deeply Virtual Compton Scattering, those asymmetries provide constraints for the nucleon Generalized Parton Distributions models. The observed shapes are in agreement with twist-2 dominance predictions.
Book Synopsis Deeply Virtual Compton Scattering and Generalized Parton Distributions by :
Download or read book Deeply Virtual Compton Scattering and Generalized Parton Distributions written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical calculations predict the modification of properties of vector mesons, such as a shift in their masses and/or broadening of their widths in dense nuclear matter. These effects can be related to partial restoration of chiral symmetry at high density or temperature. Photproduction of vector mesons off nuclei were performed at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). The data were taken with a beam of tagged photons with energies up to 4 GeV on various nuclear targets. The properties of the rho vector mesons were investigated via their rare leptonic decay to e+e-. This decay channel is preferred over hadronic modes in order to eliminate final state interactions in the nuclear matter. The combinatorial background in the mass spectrum was removed by a self-normalizing mixed-event technique. The rho meson mass distributions were extracted for each of the targets. Statistically significant results regarding medium modification of the rho meson in the nuc.
Book Synopsis Timelike Compton Scattering - A First Look (CLAS). by :
Download or read book Timelike Compton Scattering - A First Look (CLAS). written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A major goal of the 12 GeV upgrade at Jefferson Lab is to map out the Generalized Parton Distributions (GPDs) in the valence region. This is primarily done through Deeply Virtual Compton Scattering (DVCS), which provides the simplest and cleanest way of accessing the GPDs. However, the "inverse" process, Timelike Compton Scattering (TCS), can provide an important complement, in particular formeasuring the real part of the amplitude and understanding corrections at finite Q2. The first measurements of TCS have recently been carried out in Hall B at Jefferson Lab, using both tagged and untagged photon beams.
Book Synopsis Generalized Parton Distributions and Deeply Virtual Compton Scattering in Color Glass Condensate Model by :
Download or read book Generalized Parton Distributions and Deeply Virtual Compton Scattering in Color Glass Condensate Model written by and published by . This book was released on 2008 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Http://dx.doi.org/10.1140/epjc/s10052-008-0655-x Within the framework of the Color Glass Condensate model, we evaluate quark and gluon Generalized Parton Distributions (GPDs) and the cross section of Deeply Virtual Compton Scattering (DVCS) in the small-$x_{B}$ region. We demonstrate that the DVCS cross section becomes independent of energy in the limit of very small $x_{B}$, which clearly indicates saturation of the DVCS cross section. Our predictions for the GPDs and the DVCS cross section at high-energies can be tested at the future Electron-Ion Collider and in ultra-peripheral nucleus-nucleus collisions at the LHC.
Book Synopsis Deeply Virtual Compton Scattering Off Helium-4 by : Mohammad Hattawy
Download or read book Deeply Virtual Compton Scattering Off Helium-4 written by Mohammad Hattawy and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Generalized Parton Distributions (GPDs) are rich structure functions that contain information on quark/anti-quark correlations, and on correlation between longitudinal momentum and the transverse spatial position of partons. These GPDs are accessible via hard exclusive reactions such as Deeply Virtual Compton Scattering (DVCS), i.e. the leptoproduction of a real photon where the photon is emitted by the target hadron. Nuclear DVCS opens a new avenue to explore the nature of medium modifications at the partonic level. In this work, we present the first exclusive measurement of the DVCS process off helium-4 with a longitudinally polarized electron beam of 6 GeV using the CLAS detector in the experimental Hall-B at Jefferson Lab, USA. The helium-4 is of particular interest since the number of GPDs is reduced to one, because of its spin zero. The aim of this study is to understand the nuclear medium modifications of parton distributions. In our experiment, the CLAS detector was upgraded with a Radial Time Projection Chamber (RTPC) to detect the low-energy recoil nuclei, and an Inner Calorimeter (IC) to detect the forward going photons. The details of the structure, calibration and working principle of the RTPC will be presented. Then, the measurement of the beam-spin asymmetries in the DVCS channel will be presented.
Book Synopsis Deeply Virtual Compton Scattering and Nucleon Structure by : M. Garcon
Download or read book Deeply Virtual Compton Scattering and Nucleon Structure written by M. Garcon and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deeply Virtual Compton Scattering (DVCS) is the tool of choice to study Generalized Parton Distributions (GPD) in the nucleon. After a general introduction to the subject, a review of experimental results from various facilities is given. Following the first encouraging results, new generation dedicated experiments now allow unprecedented precision and kinematical coverage. Several new results were presented during the conference, showing significant progress in this relatively new field. Prospects for future experiments are presented. The path for the experimental determination of GPDs appears now open.
Book Synopsis Deeply Virtual Exclusive Processes and Generalized Parton Distributions by :
Download or read book Deeply Virtual Exclusive Processes and Generalized Parton Distributions written by and published by . This book was released on 2011 with total page 12006 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep 2!ep[gamma] in Hall A support the QCD factorization of the scattering amplitude for Q^2 e"2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p[gamma]) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The [rho] and [omega] channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the [phi]-production channel is dominated by the gluon distribution.
Book Synopsis Deeply Virtual Compton Scattering and Meson Production at Jlab/CLAS. by :
Download or read book Deeply Virtual Compton Scattering and Meson Production at Jlab/CLAS. written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviews the recent experimental results from the CLAS collaboration (Hall B of Jefferson Lab, or JLab) on Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) and discusses their interpretation in the framework of Generalized Parton Distributions (GPDs). The impact of the experimental data on the applicability of the GPD mechanism to these exclusive reactions is discussed. Initial results obtained from JLab 6 GeV data indicate that DVCS might already be interpretable in this framework while GPD models fail to describe the exclusive meson production (DVMP) data with the GPD parameterizations presently used. An exception is the? meson production for which the GPD mechanism appears to apply. The recent global analyses aiming to extract GPDs from fitting DVCS CLAS and world data are discussed. The GPD experimental program at CLAS12, planned with the upcoming 12 GeV upgrade of JLab, is briefly presented.
Book Synopsis Deeply Virtual Compton Scattering on Longitudinally Polarized Protons and Neutrons at CLAS. by :
Download or read book Deeply Virtual Compton Scattering on Longitudinally Polarized Protons and Neutrons at CLAS. written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH3) and deuterons (ND3) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.
Book Synopsis Deeply Virtual Compton Scattering at Jefferson Lab by : Frédéric Georges
Download or read book Deeply Virtual Compton Scattering at Jefferson Lab written by Frédéric Georges and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduced in the mid 90's, Generalized Parton Distributions (GPDs) are now a key element in the study of the nucleon internal structure. GPDs are a generalization of Form Factors and Parton Distribution Functions. They encapsulate both spatial and momentum distributions of partons inside a nucleon, allowing to perform its three-dimensional tomography. Furthermore, they allow to derive the total orbital angular momentum of quarks through the Ji sum rule, which is a crucial point to unravel the nucleon spin structure. By providing a more complete description of hadrons in terms of quarks and gluons, a deeper understanding of Quantum Chromodynamics can be reached.GPDs are experimentally accessible through deeply exclusive electro-production processes, and one of the simplest channels available is Deeply Virtual Compton Scattering (DVCS). A worldwide experimental program was started in the early 2000's to extract these GPDs. The DVCS experiment E12-06-114 performed at Jefferson Laboratory Hall A (Virginia, USA) between 2014 and 2016, is encompassed in this program. The aim of this experiment is to extract with high precision the DVCS helicity-dependent cross sections as a function of the momentum transfer Q2, for fixed values of the Bjorken variable xBj, on a proton target. The recent upgrade of the accelerator facility to 12 GeV allows to cover a larger Q2 range than in previous measurements and probe yet unexplored kinematic regions, while the polarized electron beam allows the separation of the contributions from the real and imaginary parts of the DVCS amplitude to the total cross section. In this document, a brief summary of the worldwide experimental program for the study of GPDs will be provided, followed by a description of the E12-06-114 apparatus and data analysis. Finally, the results of the unpolarized and polarized cross-section measurements are presented and compared to a few selected models.
Book Synopsis Generalized Parton Distributions by :
Download or read book Generalized Parton Distributions written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive electroproduction processes require a generalization of the usual parton distributions for the case when long-distance information is accumulated in non-diagonal matrix elements of quark and gluon light-cone operators. I describe two types of nonperturbative functions parametrizing such matrix elements: double distributions and skewed parton distributions, discuss their general properties, relation to the usual parton densities and form factors, evolution equations for both types of generalized parton distributions (GPD), models for GPDs and their applications in virtual and real Compton scattering.
