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 An Overview of Longitudinal Spin Structure Measurements from JLab written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Jefferson Lab is currently one of the facilities leading the investigation of the spin structure of the nucleon. Over the past 15 years, several high precision measurements have been completed, extending our knowledge of the polarized structure functions g1 and g2 down to Q2 = 0.02 GeV2. In particular, the low-Q2 range (≤ 0.1 GeV2) from these data allows us to make a benchmark-check of Chiral Perturbation theory ([chi]PT). Previous results for the moments of the spin structure functions in this region have shown mixed agreement. For [Gamma]1, the first moment of g1, we find good consistency between data and theory. However, we have seen a surprisingly large discrepancy with [chi]PT calculations for the [delta]{sub LT} spin polarizability on the neutron, which is significantly less sensitive to the [Delta]-resonance contribution. These proceedings will discuss the recent experimental effort at low Q2 from Jefferson Lab, including a discussion of preliminary results on the neutron. The new results on the neutron still show a sizeable discrepancy between data and theory. However, new calculations show improved agreement with data for some observables. In addition, new proton data for g2 is also expected to help resolve the disagreement for [delta]{sub LT}.
Download or read book Neutron Spin Structure Measurements in JLab Hall A written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress from Jefferson Lab has significantly improved our understanding of the nucleon spin structure in the high-x region. Results from two experiments in Hall A are presented. The first experiment is a precision measurement of the neutron spin asymmetry, A1(superscript n), in the high-x (valence quark) region. The results show for the first time that A1(superscript n) becomes positive at large x, strongly breaking SU(6) (spin-flavor) symmetry. The data trend is in good agreement with SU(6)-breaking valence quark models and with the fits to the previous world data. Combining the A1(superscript n) results with the world A1(superscript n) data, the up and down quark spin distributions in the nucleon were extracted. The results showed that for the proton the valence down quark spin is in the opposite direction from that of the proton, in disagreement with predictions of leading-order perturbative QCD models, which neglect quark orbital angular momentum.
Download or read book Precision Measurements of the Neutron Spin Structure at Jefferson Lab Hall A written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present here recent progress on the experimental study of the neutron spin structure at Jefferson Lab Hall A. They focus on two precision experiments. The physics motivation and the experimental setup will be described first. Then they present results for the neutron spin asymmetry A1(superscript n) and results for spin-flavor decomposition of the nucleon spin in the valence quark region, and preliminary results for the neutron spin structure function g2(superscript n) at low Q2.
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 Precision Exploration of Neutron Spin Structure at Jefferson Lab written by Nilanga Liyanage and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions provide basic information about the spin of the quark distributions inside the nucleon. Experimental understanding of the nucleon spin in the kinematic region where the three basic (''valence'') quarks dominate the nucleon wave function is still rather poor. Jefferson lab, with its high quality, high polarization continuous electron beam, and a high density polarized 3He target in experimental Hall A, provides the ideal opportunity to gather neutron spin structure data in the valence region with unprecedented precision. Two high precision neutron spin structure measurements were completed in Hall A last summer. The first experiment measured the spin asymmetry A1(N) in the valence region while in second experiment higher-twist effects were studied via measurements of gn2. The planed upgrade of Jefferson lab CEBAF accelerator to 12 GeV will significantly increase the accessible kinematic range and the precision of these measurements.
Download or read book Jefferson Lab Physics Overview written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I review highlights of the Jefferson Lab nucleon structure program. I shall emphasize recent results from experiments exploring the spin structure of the nucleon and from dedicated experiments aimed at accessing the generalized parton distributions (GPDs).
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.
Download or read book Measurement of Spin Structure Functions at Low to 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 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 Gamma1 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.
Download or read book Spin Structure of the Nucleon written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress in the study of the nucleon structure at Jefferson Lab is presented. Precision measurements of spin asymmetry in the valence quark (large x) region are shown and the polarized quark distributions were extracted. The results were in disagreement with predictions from the leading-order pQCD calculations assuming hadron helicity conservation and revealed the importance of the quark orbital angular momentum. Results on sum rules and moments of the nucleon spin structure functions in the low to intermediate Q2 range are also presented. They provide a bridge between the quark-gluon picture of the nucleon and the coherent hadronic picture. In particular, at low Q2 the results were compared with Chiral Perturbation Theory calculations. Other experiments are also briefly discussed.
Download or read book Nucleon Spin Structure Study at Jefferson Lab written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I will first review the latest development in the nucleon spin structure study with lepton- nucleon deep inelastic scattering (DIS) from high energy laboratories. I will then concentrate on the progress and plan of study of the nucleon spin structure in the low energy region. With the newly built high luminosity 6 GeV electron beam accelerator and the progress in the highly polarized electron source and highly polarized targets, new experiments are being carried out at Jefferson Lab (CEBAF) to study the nucleon spin structure in the resonance region at low Q2, with focus on the generalized GDH sum rule. Some preliminary results are presented. A generalized GDH sum rule study could provide a first comparison of experimental data with calculations from a fundamental theory over the entire Q2 regime. Taking advantage of the high luminosity of Jefferson Lab, selected spin structure experiments in the DIS region are also planned, concentrating in the valence quark region and the stud y of the quark-gluon correlations through higher twist effects. The parton-hadron duality provides the link between the DIS and the resonance region. Experimental study of duality in spin structure is planned. Outlook of spin structure study with a future 12 GeV energy upgraded Jefferson Lab is discussed.
Download or read book Jefferson Lab 12 GeV Spin Program written by Nilanga Liyanage and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin structure functions provide basic information about the spin of the quark distributions inside the nucleon. Experimental understanding of the nucleon spin in the kinematic region where the three basic ("valence") quarks dominate the nucleon wave function is still rather poor. Jefferson lab, with its high quality, high polarization continuous electron beam and state of the art polarized nucleon targets in each of its three experimental halls is ideally suited for spin structure measurements in the valence region. An experimental program is underway at Jefferson Lab to measure the spin structure of the nucleon in the valence region with unprecedented precision. The planed upgrade of Jefferson lab CEBAF accelerator to 12 GeV will significantly increase the accessible kinematic range and the precision of these measurements.
Download or read book Flavor Decomposition of Nucleon Spin Structure written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We propose to measure the semi-inclusive double-spin asymmetries in deep-inelastic (, eh)X and (, eh)X reactions (h = +, -, K+ and K- ) on longitudinally polarized NH3 and LiD targets. The high statistic data will allow a leading order five-flavor decomposition (Delta u, Delta d, Delta u, Delta d, Delta s) of the nucleon spin structure in the region of x = 0.12 H"0.43 at a Q2 of 1.21 H"3.22 GeV2. The combined spin dependent pi+ + pi- yield ratios will be measured, since the acceptance and the hadron efficiencies of the detectors can be accurately determined. Independent of fragmentation functions and parton distributions, the z-dependence (z = 0.38 H"0.71) of the combined ratios provides a build-in test of factorization at the moderate Q2. We estimate statistical uncertainties associated with such measurements.
Download or read book Clemens Paul Lewis written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The folder may include clippings, announcements, small exhibition catalogs, and other ephemeral items.
Download or read book Transverse Spin Structure of the Nucleon Through Target Single Spin Asymmetry in Semi Inclusive Deep Inelastic e E prime pi pm Reaction at Jefferson Lab written by and published by . This book was released on 2011 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to perform precision studies of the transverse spin and transverse-momentum-dependent structure in the valence quark region for both the proton and the neutron. In this paper, we focus our discussion on a recently approved experiment on the neutron as an example of the precision studies planned at JLab. The new experiment will perform precision measurements of target Single Spin Asymmetries (SSA) from semi-inclusive electro-production of charged pions from a 40-cm long transversely polarized $^3$He target in Deep-Inelastic-Scattering kinematics using 11 and 8.8 GeV electron beams. This new coincidence experiment in Hall A will employ a newly proposed solenoid spectrometer (SoLID). The large acceptance spectrometer and the high polarized luminosity will provide precise 4-D ($x$, $z$, $P_T$ and $Q^2$) data on the Collins, Sivers, and pretzelocity asymmetries for the neutron through the azimuthal angular dependence. The full 2$\pi$ azimuthal angular coverage in the lab is essential in controlling the systematic uncertainties. The results from this experiment, when combined with the proton Collins asymmetry measurement and the Collins fragmentation function determined from the e$^+$e$^-$ collision data, will allow for a quark flavor separation in order to achieve a determination of the tensor charge of the d quark to a 10% accuracy. The extracted Sivers and pretzelocity asymmetries will provide important information to understand the correlations between the quark orbital angular momentum and the nucleon spin and between the quark spin and nucleon spin.
Download or read book Spin Structure Function Measurements in Hall C at Jefferson Lab written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This presentation introduces the spin structure functions and resonant spin structure, and it discusses the experimental approaches for studying spin structure via polarized electron beam interactions with frozen polarized proton and deuteron targets.
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.
