Download or read book Sum Rule Measurements of the Spin dependent Compton Amplitude nucleon Spin Structure at Q2 written by and published by . This book was released on 1995 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy weighted integrals of the difference in helicity-dependent photo-production cross sections (?{sub {1/2}} -?32) provide information on the nucleons̀ Spin-dependent Polarizability , and on the spin-dependent part of the asymptotic forward Compton amplitude through the Drell-Hearn-Gerasimov (DHG) sum rule. (The latter forms the Q2=0 limit of recent spin-asymmetry experiments in deep-inelastic lepton-scattering.) There are no direct measurements of?{sub {1/2}} or?32, for either the proton or the neutron. Estimates from current?-photo-production multipole analyses, particularly for the proton-neutron difference, are in good agreement with relativistic-l-loop Chiral calculations (?PT) for? but predict large deviations from the DHG sum rule. Either (a) both the 2-loop corrections to the Spin-Polarizability are large and the existing multipoles are wrong, or (b) modifications to the Drell-Hearn-Gerasimov sum rule are required to fully describe the isospin structure of the nucleon. The helicity-dependent photo-reaction amplitudes, for both the proton and the neutron, will be measured at LEGS from pion-threshold to 470 MeV. In these double-polarization experiments, circularly polarized photons from LEGS will be used with SPHICE, a new frozen-spin target consisting of {rvec H} · {rvec D} in the solid phase. Reaction channels will be identified in SASY, a large detector array covering about 80% of 4?. A high degree of symmetry in both target and detector will be used to minimize systematic uncertainties.

Download or read book Sum Rule Measurements of the Spin dependent Compton Amplitude nucleon Spin Structure at Q sup 2 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy weighted integrals of the difference in helicity-dependent photo-production cross sections ([sigma][sub [1/2]] - [sigma][sub 3/2]) provide information on the nucleon's Spin-dependent Polarizability ([gamma]), and on the spin-dependent part of the asymptotic forward Compton amplitude through the Drell-Hearn-Gerasimov (DHG) sum rule. (The latter forms the Q[sup 2]=0 limit of recent spin-asymmetry experiments in deep-inelastic lepton-scattering.) There are no direct measurements of [sigma][sub [1/2]] or [sigma][sub 3/2], for either the proton or the neutron. Estimates from current [pi]-photo-production multipole analyses, particularly for the proton-neutron difference, are in good agreement with relativistic-l-loop Chiral calculations ([chi]PT) for [gamma] but predict large deviations from the DHG sum rule. Either (a) both the 2-loop corrections to the Spin-Polarizability are large and the existing multipoles are wrong, or (b) modifications to the Drell-Hearn-Gerasimov sum rule are required to fully describe the isospin structure of the nucleon. The helicity-dependent photo-reaction amplitudes, for both the proton and the neutron, will be measured at LEGS from pion-threshold to 470 MeV. In these double-polarization experiments, circularly polarized photons from LEGS will be used with SPHICE, a new frozen-spin target consisting of [rvec H] [center-dot] [rvec D] in the solid phase. Reaction channels will be identified in SASY, a large detector array covering about 80% of 4[pi]. A high degree of symmetry in both target and detector will be used to minimize systematic uncertainties.

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).

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.

Download or read book The Spin Structure Of The Nucleon written by Bernard Frois and published by World Scientific. This book was released on 1998-02-24 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: From its early beginnings at SLAC in the 1970's, the study of nucleon spin structure using polarized lepton beams and polarized nucleon targets has become increasingly important in nuclear and particle physics, with current experiments at several of the world's high energy and nuclear physics laboratories (CERN, DESY, SLAC and Jefferson Lab) and with enormous related theoretical studies. The understanding of the fascinating but complicated problem of nucleon spin structure has progressed substantially, but fundamental questions remain and it can be confidently predicted that future activity will be high.The Erice Course on The Spin Structure of the Nucleon covered both the experimental and theoretical aspects of the subject, and this volume includes the lectures given at the School. In many cases the lecture material has been extended and updated by the authors. In addition, several recent publications on experimental work have been added in an appendix.

Download or read book Gdh 2000 The Gerasimov drell hearn Sum Rule The Nucleon Spin Structure In The Resonance Region written by Dieter Drechsel and published by World Scientific. This book was released on 2001-02-05 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 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.

Download or read book Frontier 96 Nuclear Physics Frontiers With Electroweak Probes Proceedings Of Xv Rcnp Osaka International Symposium written by Hiroshi Toki and published by World Scientific. This book was released on 1996-10-25 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spin Structure at Long Distance written by Jian-Ping Chen and published by AIP Conference Proceedings (Nu. This book was released on 2009-08-04 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical developments -- Experimental developments -- Future experiments and active analyses.

Download or read book Excited Nucleons and Hadronic Structure written by V. Burkert and published by World Scientific. This book was released on 2001 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conference NSTAR 2000 was part of a series of conferences and workshops that began in New York in 1988. Since then, the field of excited nucleons and hadron structure has developed enormously, and the scope has broadened. Most significantly, new experimental facilities have come into operation, allowing precise measurements of resonance couplings and transition form factors. The search for ?missing? quark model states and gluonic excitations in complex hadronic channels is now possible.On the theory side, new and promising developments have emerged: quark models with meson degrees of freedom, hybrid baryon models, and studies of baryons in the limit of many colors. For the first time, lattice QCD has been employed to calculate masses of excited nucleons. Nucleon resonances are now recognized as providing significant contributions to the nucleon spin sum rules, as well as the Gerasimov-Drell-Hearn and Bjorken integrals, at finite momentum transfer.

Download or read book Measurement of the Spin Structure Function G1 x Q2 of the Proton in the Resonance Region written by Yelena Alexandrovna Prok and published by . This book was released on 2004 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book GDH 2002 written by Marco Anghinolfi and published by World Scientific. This book was released on 2003 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Containing the proceedings of the GDH 2002 symposium, this is a review of results on the nucleon spin structure and related sum rules using real and virtual photons. Theoretical developments and high precision data from different laboratories are presented and discussed. The work offers a comprehensive picture of the nucleon spin studies from the perturbative domain down to the resonance and low momentum transfer region.

Download or read book Gdh 2004 Proceedings Of The Third International Symposium On The Gerasimov drell hearn Sum Rule And Its Extensions written by Sebastian Kuhn and published by World Scientific. This book was released on 2005-02-21 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents an overview of the many new and exciting results, both theoretical and experimental, in the area of spin structure functions and sum rules at low to moderate photon virtuality Q2. It includes contributions from many leading scientists in the field worldwide.The volume covers the following topics:• recent results on the Gerasimov-Drell-Hearn (GDH) sum rule with real photons and its extensions to virtual photons• inclusive spin structure functions at low to moderate Q2 and their moments• exclusive measurements of nucleon spin structure in the resonance region• spin polarizabilities and Compton scattering• chiral perturbation theory and other low-energy limits of QCD• lattice QCD, duality, and phenomological models• nuclear effects and the GDH sum rule in nuclei• experimental techniques (polarized targets and beams)• future plans and projects

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.

Download or read book An Overview of Recent Nucleon Spin Structure Measurements at Jefferson Lab written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Jefferson Lab have made significant contributions to improve our knowledge of the longitudinal spin structure by measuring polarized structure functions, g1 and g2, down to Q2 = 0.02 GeV2. The low Q2 data is especially useful in testing the Chiral Perturbation theory (cPT) calculations. The spin-dependent sum rules and the spin polarizabilities, constructed from the moments of g1 and g2, provide an important tool to study the longitudinal spin structure. We will present an overview of the experimental program to measure these structure functions at Jefferson Lab, and present some recent results on the neutron polarizabilities, proton g1 at low Q2, and proton and neutron d2 measurement. In addition to this, we will discuss the transverse spin structure of the nucleon which can be accessed using chiral-odd transversity distribution (h1), and show some results from measurements done on polarized 3He target in Hall A.

Download or read book Gdh 2002 Proceedings Of The Second International Symposium On The Gerasimov drell hearn Sum Rule And The Spin Structure Of The Nucleon written by Marco Anghinolfi and published by World Scientific. This book was released on 2003-06-13 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the GDH 2002 symposium. It is a review of the most recent results on the nucleon spin structure and related sum rules using real and virtual photons. The latest theoretical developments and the new high precision data from different laboratories are presented and discussed. The book provides a comprehensive picture of the nucleon spin studies from the perturbative domain down to the resonance and low momentum transfer region.

Download or read book Chiral Dynamics 2006 Proceedings Of The 5th International Workshop On Chiral Dynamics Theory And Experiment written by Mohammad W Ahmed and published by World Scientific. This book was released on 2007-10-18 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chiral Dynamics 2006 is the 5th International Workshop which examines the implications and the development of an approximate low-energy solution to the QCD Lagrangian based upon Chiral Symmetry. Advances in theory and experiment are presented in 20 plenary session papers along with more than one-hundred papers, including summaries, from the three working groups.