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Moments Of Spin Structure Functions
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Book Synopsis Moments of the Spin Structure Functions G1p and G1d for 0.05 [Q2 [3.0 GeV2 by :
Download or read book Moments of the Spin Structure Functions G1p and G1d for 0.05 [Q2 [3.0 GeV2 written by and published by . This book was released on 2009 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spin structure functions $g_1$ for the proton and the deuteron have been measured over a wide kinematic range in $x$ and \Q2 using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH$_3$ and ND$_3$ targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for $0.05
Book Synopsis Moments of Spin Structure Functions by :
Download or read book Moments of Spin Structure Functions written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight for some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e. the Bjorken, Burkhardt-Cottingham, Gerasimov-Drell-Hearn (GDH), and the generalized GDH). These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers.
Book Synopsis Sum Rules and Moments of the Nucleon Spin Structure Functions by :
Download or read book Sum Rules and Moments of the Nucleon Spin Structure Functions written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The nucleon has been used as a laboratory to investigate its own spin structure and Quantum Chromodynamics. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture of the transition region from the confinement regime of the theory to its asymptotic freedom regime. Insight for some aspects of the theory is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e. the Gerasimov-Drell-Hearn, Bjorken and Burkhardt-Cottingham). These moments are expressed in terms of an operator product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The sum rules are verified to a good accuracy assuming that no singular behavior of the structure functions is present at very high excitation energies. The higher twist contributions have been examined through the moments evolution as the momentum transfer varies from higher to lower values. Furthermore, QCD-inspired low energy effective theories, which explicitly include chiral symmetry breaking, are tested at low momentum transfers. The validity of these theories is further examined as the momentum transfer increases to moderate values. It is found that chiral perturbation calculations agree reasonably well with the first moment of the spin structure function g1 at momentum transfer of 0.1 GeV2 but fail to reproduce the neutron data in the case of the generalized polarizability [delta]{sub LT}.
Book Synopsis Consistent Higher-twists Analysis of Moments of Spin Structure Function by :
Download or read book Consistent Higher-twists Analysis of Moments of Spin Structure Function written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Jefferson Lab's Results on the Q2-evolution of Moments of Spin Structure Functions by :
Download or read book Jefferson Lab's Results on the Q2-evolution of Moments of Spin Structure Functions written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the recent JLab measurements on moments of spin structure functions at intermediate and low Q2. The Bjorken sum and Burkhardt-Cottingham sum on the neutron are presented. The later appears to hold. Higher moments (generalized spin polarizabilities and d2(superscript n)) are shown and compared to chiral perturbation theory and lattice QCD respectively.
Book Synopsis Spin Structure Moments of the Proton and Deuteron by :
Download or read book Spin Structure Moments of the Proton and Deuteron written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Moments of the spin structure functions g1 and g2 of the proton and deuteron have been measured in the resonance region at intermediate four momentum transfer. We perform a Nachtmann moment analysis of this data, along with isovector and isoscalar combinations, in order to rigorously account for target mass effects. This analysis provides the first definitive evidence for dynamic higher twists.
Book Synopsis Measurement of Spin Structure Functions at Moderate Q{sup 2} Using CLAS. by : Volker Burkert
Download or read book Measurement of Spin Structure Functions at Moderate Q{sup 2} Using CLAS. written by Volker Burkert and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions of the nucleon in the region of large z and small to moderate Q{sup 2} continue to be of high current interest. Among the topics one can study in this kinematic regime are spin-dependent resonance transition amplitudes and their interference with each other and the non-resonant background, the behavior of the asymmetry A{sub 1} at large x, and the presence or absence of local duality in spin structure functions. The first moment of the spin structure function g{sub 1} goes through a rapid transition from the photon point (Q{sup 2} = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. This opens up the possibility to study the transition from hadronic to quark degrees of freedom over the whole range of Q{sup 2}. Recently, we concluded a large experimental program to measure these observables with polarized proton and deuteron targets at Jefferson Lab. A highly polarized electron beam, solid polarized NH{sub 3} and ND{sub 3} targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to accumulate over 23 billion events with 4 different beam energies of 1.6, 2.5, 4.2 and 5.7 GeV. We present an overview of the experiment, its kinematic coverage and its statistical power. We show final results from the first run at 2.5 GeV and 4 GeV and preliminary results from the 5.7 GeV and the 1.6 GeV data sets.
Book Synopsis Spin Structure Functions of the Deuteron Measured with CLAS in and Above the Resonance Region by :
Download or read book Spin Structure Functions of the Deuteron Measured with CLAS in and Above the Resonance Region written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions of the nucleon in the region of large x and small to moderate Q2 continue to be of high current interest. The first moment of the spin structure function g1, [Gamma]1, goes through a rapid transition from the photon point (Q2=0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. The interesting behavior in the transition region is dominated by baryon resonance excitations. We concluded an experiment to measure these observables for deuterium as part of the ''EG1'' run group in Jefferson Lab's Hall B. We used a highly polarized electron beam with energies from 1.6 GeV to 5.7 GeV and a cryogenic polarized ND3 target together with the CEBAF Large Acceptance Spectrometer (CLAS) to accumulate over 11 billion events. In this thesis, we present results for the spin structure function g1{sup d} (x, Q2), as well as its first moment, [Gamma]1{sup d}(Q2) in and above the resonance region over a Q2 range from 0.05 to 5 Gev2, based on the data taken with beam energies of 1.6 and 5.7 GeV. We also extract the behavior of A1{sup d}(x) at large x. Our data are consistent with the Hyperfine-perturbed quark model calculation which predicts that A1{sup d} (x 2!1) 2!1. We also see evidence for duality in g1{sup d} (x, Q2) at Q2> GeV2.
Download or read book Spin Structure Functions written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A large program of spin structure measurements is underway in Jefferson Lab's Hall B. Of particular interest is the first moment of the spin structure function g1, which goes through a rapid transition from the photon point (Q2 = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. One can then study the transition from hadronic to quark degrees of freedom over the whole range of Q2. It is also interesting to look for the onset of quark-hadron duality in spin structure functions. We use longitudinally polarized electrons with energies from 1.6 to 5.7 GeV incident upon polarized NH3 and ND3 targets to investigate proton and deuteron spin observables in and above the resonance region. We present the GDH and Bjorken integrals using the 1.6 and 5.7 GeV data and comment on the validity of local quark-hadron duality over the wide kinematical range (0.05? Q2? 4.5 GeV2 and W
Book Synopsis Spin Structure Functions of the Deuteron Measured with Clas in and Above the Resonance Region by : Kahanawita G. Vipuli G. Dharmawardane
Download or read book Spin Structure Functions of the Deuteron Measured with Clas in and Above the Resonance Region written by Kahanawita G. Vipuli G. Dharmawardane and published by . This book was released on 2004 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Higher Moments of Nucleon Spin Structure Functions in Heavy Baryon Chiral Perturbation Theory and in a Resonance Model by :
Download or read book Higher Moments of Nucleon Spin Structure Functions in Heavy Baryon Chiral Perturbation Theory and in a Resonance Model written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The third moment d2 of the twist-3 part of the nucleon spin structure function g2 is generalized to arbitrary momentum transfer Q2 and is evaluated in heavy baryon chiral perturbation theory (HBChPT) up to order [Omicron](p4) and in a unitary isobar model (MAID). We show how to link d2 as well as higher moments of the nucleon spin structure functions g1 and g2 to nucleon spin polarizabilities. We compare our results with the most recent experimental data, and find a good description of these available data within the unitary isobar model. We proceed to extract the twist-4 matrix element f2 which appears in the 1/Q2 suppressed term in the twist expansion of the spin structure function g1 for proton and neutron.
Book Synopsis Spin Structure Of The Nucleon - Proceedings Of The The Riken Symposium by : Toshi-aki Shibata
Download or read book Spin Structure Of The Nucleon - Proceedings Of The The Riken Symposium written by Toshi-aki Shibata and published by World Scientific. This book was released on 1996-08-30 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: After about three decades of experimental and theoretical efforts, the structure of the nucleon (proton and neutron) is now fairly well understood based on quantum chromodynamics, but only if averaged over its spin. As the recent “proton spin crisis” revealed, we do not understand much about the nucleon structure when its spin is polarized to a specific orientation. We expect that our understanding on this challenging problem will soon be significantly improved by the RHIC-Spin and other experiments in the near future, as well as by the lattice- and perturbative-QCD theoretical calculations. The purpose of this symposium was to summarize the current understanding and discuss the future perspective of this problem with experimental and theoretical physicists from both high-energy and nuclear physics communities.The symposium covered the overview of the structure studies, updates on the experimental results from CERN, SLAC, DESY, FNAL, and KEK, future experiments at RHIC, and recent theoretical developments (18 presentations, 113 participants).
Book Synopsis Measurement of Spin Structure Functions at Moderate Q2 Using CLAS. by :
Download or read book Measurement of Spin Structure Functions at Moderate Q2 Using CLAS. written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions of the nucleon in the region of large z and small to moderate Q2 continue to be of high current interest. Among the topics one can study in this kinematic regime are spin-dependent resonance transition amplitudes and their interference with each other and the non-resonant background, the behavior of the asymmetry A1 at large x, and the presence or absence of local duality in spin structure functions. The first moment of the spin structure function g1 goes through a rapid transition from the photon point (Q2 = 0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. This opens up the possibility to study the transition from hadronic to quark degrees of freedom over the whole range of Q2. Recently, we concluded a large experimental program to measure these observables with polarized proton and deuteron targets at Jefferson Lab. A highly polarized electron beam, solid polarized NH3 and ND3 targets and the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B were used to accumulate over 23 billion events with 4 different beam energies of 1.6, 2.5, 4.2 and 5.7 GeV. We present an overview of the experiment, its kinematic coverage and its statistical power. We show final results from the first run at 2.5 GeV and 4 GeV and preliminary results from the 5.7 GeV and the 1.6 GeV data sets.
Book Synopsis Measurement of Spin Structure Functions at Low to Moderate Q{sup 2} Using CLAS. by : CLAS Collaboration
Download or read book Measurement of Spin Structure Functions at Low to Moderate Q{sup 2} Using CLAS. written by CLAS Collaboration and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions of the nucleon in the region of large x and small to moderate Q2 continue to be of high current interest. A large experimental program to measure the spin structure function g1 and its first moment Gamma{sub 1} has been concluded at Jefferson Lab. An overview of the experiment and its kinematic coverage will be discussed. We will also show preliminary results from the 5.7 GeV and the 1.6 GeV data sets.
Book Synopsis New Results on Nucleon Spin Structure by :
Download or read book New Results on Nucleon Spin Structure written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent precision spin structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence quark (high-x) region and improved our understanding of higher-twist effects, spin sum rules and quark-hadron duality. First, results of a precision measurement of the neutron spin asymmetry, A[sub 1][sup n], in the high-x region are discussed. The new data shows clearly, for the first time, that A[sub 1][sup n] becomes positive at high x. They provide crucial input for the global fits to world data to extract polarized parton distribution functions. Preliminary results on A[sub 1][sup p] and A[sub 1][sup d] in the high-x region have also become available. The up and down quark spin distributions in the nucleon were extracted. The results for [Delta]d/d disagree with the leading-order pQCD prediction assuming hadron helicity conservation. Then, results of a precision measurement of the g[sub 2][sup n] structure function to study higher-twist effects are presented. The data show a clear deviation from the lead-twist contribution, indicating a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d[sub 2][sup n] results were extracted at a high Q[sup 2] of 5 GeV[sup 2] from the measured A[sub 2][sup n] in the high-x region in combination with existing world data and compared with a Lattice QCD calculation. Results for d[sub 2][sup n] at low-to-intermediate Q[sup 2] from 0.1 to 0.9 GeV[sup 2] were also extracted from the JLab data. In the same Q[sup 2] range, the Q[sup 2] dependence of the moments of the nucleon spin structure functions was measured, providing a unique bridge linking the quark-gluon picture of the nucleon and the coherent hadronic picture. Sum rules and generalized forward spin polarizabilities were extracted and compared with Chiral Perturbation Theory calculations and phenomenological models. Finally, preliminary results on the resonance spin structure functions in the Q[sup 2] range from 1 to 4 GeV[sup 2] were presented, which, in combination with DIS data, will enable a detailed study of the quark-hadron duality in spin structure functions.
Book Synopsis Internal Spin Structure Of The Nucleon - Proceedings Of The Symposium by : Vernon W Hughes
Download or read book Internal Spin Structure Of The Nucleon - Proceedings Of The Symposium written by Vernon W Hughes and published by World Scientific. This book was released on 1995-07-14 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: The topic of the internal spin structure of the nucleon has become an unusually active subfield of particle and nuclear physics, together with the relevant technologies. This volume presents up-to-date coverage.All the talks given at the symposium can be found in the volume. In addition, selected articles are reprinted, including two early papers which record initial thinking about the topic, all experimental papers giving data on nucleon spin structure functions determined from polarized lepton-nucleon scattering, and two valuable previously unpublished papers.
Book Synopsis The Spin Structure of the Proton by : Steven D. Bass
Download or read book The Spin Structure of the Proton written by Steven D. Bass and published by World Scientific. This book was released on 2008 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main challenges in nuclear and particle physics in the last 20 years has been to understand how the proton''s spin is built up from its quark and gluon constituents. Quark models generally predict that about 60% of the proton''s spin should be carried by the spin of the quarks inside, whereas high energy scattering experiments have shown that the quark spin contribution is small OCo only about 30%. This result has been the underlying motivation for about 1000 theoretical papers and a global program of dedicated spin experiments at BNL, CERN, DESY and Jefferson Laboratory to map the individual quark and gluon angular momentum contributions to the proton''s spin, which are now yielding exciting results. This book gives an overview of the present status of the field: what is new in the data and what can be expected in the next few years. The emphasis is on the main physical ideas and the interpretation of spin data. The interface between QCD spin physics and the famous axial U(1) problem of QCD (eta and etaprime meson physics) is also highlighted. Sample Chapter(s). Chapter 1: Introduction (159 KB). Contents: Spin Experiments and Data; Dispersion Relations and Spin Sum Rules; g 1 Spin Sum Rules; Fixed Poles; The Axial Anomaly, Gluon topology and g (0) A; Chiral Symmetry and Axial U(1) Dynamics; QCD Inspired Models of the Proton Spin Problem; The Spin-Flavour Structure of the Proton; QCD Fits to g 1 Data; Polarized Quark Distributions; Polarized Glue o g(x, Q 2 ); Transversity; Deeply Virtual Compton Scattering and Exclusive Processes; Polarized Photon Structure Functions; Conclusions and Open Questions: How Does the Proton Spin?. Readership: Academics, as well as physicists working on particle and nuclear physics at the interface of theory and experiment.
