Download or read book Deeply Virtual Compton Scattering Beam Spin Asymmetries written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The beam spin asymmetries in the hard exclusive electroproduction of photons on the proton (ep -> epg) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x_B from 0.11 to 0.58, Q^2 from 1 to 4.8 GeV^2, -t from 0.09 to 1.8 GeV^2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A = a*sin[phi]/[1+c*cos[phi]]. This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.
Download or read book Beam Spin Asymmetry Measurements in Deeply Virtual Compton Scattering written by Gagik Gavalian and published by . This book was released on 2004 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Beam Spin Asymmetries in DVCS with CLAS at 4 8 GeV written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report measurements of the beam spin asymmetry in Deeply Virtual Compton Scattering (DVCS) at an electron beam energy of $4.8$ GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, $1$(GeV/c)$^2$ $
Download or read book Beam spin Asymmetry of Deeply Virtual Compton Scattering Off the Proton at 10 6 GeVwith CLAS12 at Jefferson Laboratory written by Guillaume Christiaens and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Beam charge and Beam spin Azimuthal Asymmetries in Deeply virtual Compton Scattering written by Frank Ellinghaus and published by . This book was released on 2004 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Target spin Asymmetry Measurements for Deeply Virtual Compton Scattering on Longitudinally Polarized Protons written by Erin E. Seder and published by . This book was released on 2013 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Single and Double Spin Asymmetries for Deeply Virtual Compton Scattering Measured with CLAS and a Longitudinally Polarized Proton Target written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton e→p→e'p'[gamma] are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized 14NH3 target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. As a result, the measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the H and H~ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.
Download or read book Measurement of the Beam spin Azimuthal Asymmetry Associated with Deeply virtual Compton Scattering written by and published by . This book was released on 2001 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Longitudinal Target spin Asymmetries for Deeply Virtual Compton Scattering written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and [Phi], for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.
Download or read book Triple Coincidence Beam Spin Asymmetry Measurements in Deeply Virtual Compton Scattering written by Mustafa Canan and published by . This book was released on 2011 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Deeply Virtual Compton Scattering at 6 GeV written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors propose a measurement of the Deep Virtual Compton Scattering process (DVCS) ep → ep[gamma] in Hall A at Jefferson Lab with a 6 GeV beam. The authors are able to explore the onset of Q2 scaling, by measuring a beam helicity asymmetry for Q2 ranging from 1.5 to 2.5 GeV2 at x{sub B} ≈ 0.35. At this kinematics, the asymmetry is dominated by the DVCS Bethe-Heitler (BH) interference, which is proportional to the imaginary part of the DVCS amplitude amplified by the full magnitude of the BH amplitude. The imaginary part of the DVCS amplitude is expected to scale early. Indeed, the imaginary part of the forward Compton amplitude measured in deep inelastic scattering (via the optical theorem) scales at Q2 as low as 1 GeV2. If the scaling regime is reached, they make an 8% measurement of the skewed parton distributions (SPD) contributing to the DVCS amplitude. Also, this experiment allows them to separately estimate the size of the higher-twist effects, since they are only suppressed by an additional factor 1/Q compared to the leading-twist term, and have a different angular dependence. They use a polarized electron beam and detect the scattered electron in the HRSe, the real photon in an electromagnetic calorimeter (under construction) and the recoil proton in a shielded scintillator array (to be constructed). This allows them to determine the difference in cross-sections for electrons of opposite helicities. This observable is directly linked to the SPD's. The authors estimate that 25 days of beam (600 hours) are needed to achieve this goal.
Download or read book Deeply Virtual Compton Scattering and Its Beam Charge Asymmetry in E p Collisions at HERA written by and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deeply Virtual Compton Scattering and Its Beam Charge Asymmetry in E p Collisions at HERA written by H1 Collaboration and published by . This book was released on 2009 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
