Measurement of the Generalized Polarizabilities of the Proton by Virtual Compton Scattering at MAMI and Q 2
Author: Loup Correa
Publisher:
Published: 2016
Total Pages: 0
ISBN-13:
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Author: Loup Correa
Publisher:
Published: 2016
Total Pages: 0
ISBN-13:
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Published: 2003
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DOWNLOAD EBOOKVirtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility in the energy domain below pion threshold and in the Delta(1232) resonance region. The data analysis is based on the Dispersion Relation (DR) approach. The electric and magnetic Generalized Polarizabilities (GPs) of the proton and the structure functions Pll-Ptt/epsilon and Plt are determined at four-momentum transfer squared Q2=0.92 and 1.76 GeV2. The DR analysis is consistent with the low-energy expansion analysis. The world data set indicates that neither the electric nor magnetic GP follows a simple dipole form.
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Published: 2004
Total Pages: 1
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DOWNLOAD EBOOKWe report a Virtual Compton Scattering study of the proton at low CM energies. We have determined the structure functions P{sub LL} - P{sub TT}/[epsilon] and P{sub LT}, and the electric and magnetic Generalized Polarizabilities (GPs) [alpha]{sub E}(Q2) and [beta]{sub M}(Q2) at momentum transfer Q2 = 0.92 and 1.76 GeV2. The electric GP shows a strong fall-off with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a fall-off; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from [pi]N intermediate states.
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Published: 2003
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DOWNLOAD EBOOKVirtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility at low Center-of-Mass energies, below pion threshold. Following the Low Energy Theorem for the ep --> ep gamma process, we obtain values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum transfer squared Q2=0.92 and 1.76 GeV2.
Author: Ruonan Li
Publisher:
Published: 2022
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKUnderstanding how the visible matter in the universe arises from its elementary quark andgluon constituents is a central question for science. The visible world is founded on the proton, the only composite building block of matter that is stable in nature. Consequently, understanding the formation of matter relies on explaining the dynamics and the properties of the proton's bound state. A fundamental property of the proton involves the system's response to an external electromagnetic (EM) field. It is characterized by the EM polarizabilities that describe how easily the charge and magnetization distributions inside the system are distorted by the EM field. When the polarizabilities are generalized to finite momentum transfer, their Fourier transform can map out the spatial distribution of the polarization densities in a proton subject to an EM field. This thesis focuses on the measurement of the proton generalized polarizabilities (GPs) at low four-momentum transfer in experimental Hall C at the Thomas Jefferson National Accelerator Facility (TJNAF). Among the six independent GPs, we will focus on the electric (aE1) and the magnetic (bM1) scalar GPs. The GPs can be accessed through measurements of the Virtual Compton Scattering reaction, by replacing the incoming real photon of the Compton scattering process with a space-like virtual photon. The outgoing real photon provides the EM perturbation to the system. In addition, the Dispersion Relation Formalism is used for generalized polarizability extraction. In this work, the two scalar GPs measured with unprecedented precision, and the measurements help explore a momentum transfer region where an anomalous enhancement of the electric GP that contradicts the predictions of nuclear theory has been observed.
Author: Jure Beričič
Publisher:
Published: 2015
Total Pages: 144
ISBN-13:
DOWNLOAD EBOOKAuthor: Carl Carlson
Publisher: World Scientific
Published: 1997-02-21
Total Pages: 787
ISBN-13: 981454664X
DOWNLOAD EBOOKThis book is devoted to phenomena that are of interest to both particle and nuclear physicists. The topics include nucleon structure (including spin structure), electron, neutrino, and hadron scattering from nucleons and nuclei, strange matter, the standard model, theory of nucleons and nuclei from both the QCD and nucleon-meson viewpoints, new experimental techniques, and new facilities.
Author: Antonio Dobado
Publisher: Springer Science & Business Media
Published: 2008-11-07
Total Pages: 615
ISBN-13: 3540725164
DOWNLOAD EBOOKThe QNP series of international conferences on Quarks and Nuclear Physics is by now a well established and highly respected forum where the most recent developments in the field are discussed and communicated. QNP 2006 is the forth edition of this biennial meeting. Selected and refereed original contributions of QNP 2006 have been published in The European Physical Journal A - Hadrons and Nuclei (EPJ A), while the present proceedings book, in addition to reprinting the articles published in EPJ A, further includes all other contributions selected and accepted by the organizing committee for publication and archiving.
Author: Sigfrido Boffi
Publisher: World Scientific
Published: 1997-12-16
Total Pages: 578
ISBN-13: 9814545422
DOWNLOAD EBOOKAuthor: Dieter Drechsel
Publisher: World Scientific
Published: 2001-02-05
Total Pages: 430
ISBN-13: 9814491381
DOWNLOAD EBOOKThe history of spin in general, and of the nucleon spin structure in particular, has been full of surprises. For the past 25 years deep inelastic lepton scattering has been studied to determine the carriers of the nucleon spin. However, it was realized only recently that a full understanding of the nucleon spin will also require detailed information on the helicity structure in the resonance region, i.e. in the realm of nonperturbative QCD.This volume gives a status report on the spin structure in the nucleon resonance region, focusing on: new experimental results from SLAC and HERMES; a first glance at the JLab experiments to map out the spin structure functions at low and intermediate four-momentum transfers; the pioneering experiment at MAMI (Mainz) to determine the Gerasimov-Drell-Hearn sum rule for real photons; and recent theoretical concepts and investigations to describe the spin structure in the frameworks of higher twist expansion, phenomenological models and chiral perturbation theory.