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1. Measurement of the Proton and Deuteron Spin Structure Functiong1in the Resonance Region

Author

D. Crabb, A. Rijllart, J. P. Chen, F.R. Wesselmann, G. Court, John C. Mitchell, L. S. Rochester, R. Pitthan, Timothy B. Smith, H. Tang, D. Reyna, Ingo Sick, H. Borel, B. Zihlmann, Emil Frlez, M. Kuriki, L. C. Smith, J. Fellbaum, R. Antonov, Vincent Breton, O. Rondon, K. Witte, K. P. Coulter, R. M. Lombard-Nelsen, K. A. Griffioen, J. Clendenin, E. W. Hughes, J. R. Johnson, P.L. Anthony, C. Y. Prescott, A. Feltham, R. G. Arnold, P. Raines, T. J. Liu, Dinko Pocanic, F. S. Dietrich, R. Gearhart, S. E. Rock, S. E. Kuhn, J. Gomez, F. Suekane, James L. White, P. Grenier, R. Prepost, S.St. Lorant, G. H. Zapalac, W. Meyer, J. Button-Shafer, J. Marroncle, J. A. Dunne, R. C. Minehart, Koji Abe, Z. M. Szalata, C. C. Young, D. Walz, Avraham Klein, Ch. Hyde-Wright, H. Yuta, D. Kawall, P. E. Bosted, D. Garvey, H. Fonvieille, B. Raue, H. Dutz, R. A. Lindgren, Timothy Chupp, S. Hoibraten, Pascal Steiner, F. Staley, B. Youngman, G. G. Petratos, T. Averett, R. Erbacher, Z. E. Meziani, J. Morgenstern, X.K. Maruyama, Donal Day, C. Comptour, M. Daoudi, J. M. Bauer, H. R. Band, Y. Roblin, L. M. Stuart, T. Maruyama, T. L. Usher, D. Zimmermann, Y. Terrien, J. S. McCarthy, T. Akagi, and M. Spengos

Subjects
Physics, Nuclear physics, Proton, Scattering, General Physics and Astronomy, Resonance, Electron, Atomic physics, Inelastic scattering, Spin structure, Nucleon, Spin-½
Abstract

We have measured the proton and deuteron spin structure functions g[sup p][sub 1] and g[sup d][sub 1] in the region of the nucleon resonances for W2 < 5GeV2 and Q2(similar, equals)0.5 and Q2(similar, equals)1.2GeV2 by inelastically scattering 9.7 GeV polarized electrons off polarized 15NH3 and 15ND3 targets. We observe significant structure in g[sup p][sub 1] in the resonance region. We have used the present results, together with the deep-inelastic data at higher W2, to extract Gamma (Q2)(equivalent)01 g1(x,Q2)dx. This is the first information on the low-Q2 evolution of Gamma toward the Gerasimov-Drell-Hearn limit at Q2 = 0.

Published
1997
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2. Deep inelastic scattering of polarized electrons by polarizedHe3and the study of the neutron spin structure

Author

W. Meyer, Sayed Rokni, Timothy Chupp, Y. Roblin, J. Morgenstern, C. C. Young, R. Prepost, H. Borel, E. W. Hughes, Z. M. Szalata, S. E. Rock, Timothy B. Smith, R. G. Arnold, H. Fonvieille, M. Woods, H. R. Band, F. S. Dietrich, P. E. Bosted, J. Fellbaum, F. Staley, H. Middleton, M. Spengos, Y. Terrien, Alan K. Thompson, L. M. Stuart, R. Erbacher, J. A. Dunne, T. Maruyama, J. Xu, Z. E. Meziani, Gilbert Shapiro, J. R. Johnson, N. R. Newbury, D. Kawall, G. G. Petratos, R. Holmes, G. H. Zapalac, J. Marroncle, P.L. Anthony, C. E. Keppel, James L. White, Vincent Breton, S. E. Kuhn, Gordon D. Cates, R. Pitthan, Paul A Souder, R. M. Lombard-Nelsen, and R. A. Gearhart

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Proton, High density, Neutron, Electron, Spin structure, Nucleon, Deep inelastic scattering
Abstract

The neutron longitudinal and transverse asymmetries ${A}_{1}^{n}$ and ${A}_{2}^{n}$ have been extracted from deep inelastic scattering of polarized electrons by a polarized $^{3}\mathrm{He}$ target at incident energies of 19.42, 22.66, and 25.51 GeV. The measurement allows for the determination of the neutron spin structure functions ${g}_{1}^{n}(x, {Q}^{2})$ and ${g}_{2}^{n}(x, {Q}^{2})$ over the range $0.03lxl0.6$ at an average ${Q}^{2}$ of 2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. The data are used for the evaluation of the Ellis-Jaffe and Bjorken sum rules. The neutron spin structure function ${g}_{1}^{n}(x, {Q}^{2})$ is small and negative within the range of our measurement, yielding an integral $\ensuremath{\int}{0.03}^{0.6}{g}_{1}^{n}(x)\mathrm{dx}=\ensuremath{-}0.028\ifmmode\pm\else\textpm\fi{}0.006 (\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.006 (\mathrm{syst})$. Assuming Regge behavior at low $x$, we extract ${\ensuremath{\Gamma}}_{1}^{n}=\ensuremath{\int}{0}^{1}{g}_{1}^{n}(x)\mathrm{dx}=\ensuremath{-}0.031\ifmmode\pm\else\textpm\fi{}0.006 (\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.009 (\mathrm{syst})$. Combined with previous proton integral results from SLAC experiment E143, we find ${\ensuremath{\Gamma}}_{1}^{p}\ensuremath{-}{\ensuremath{\Gamma}}_{1}^{n}=0.160\ifmmode\pm\else\textpm\fi{}0.015$ in agreement with the Bjorken sum rule prediction ${\ensuremath{\Gamma}}_{1}^{p}\ensuremath{-}{\ensuremath{\Gamma}}_{1}^{n}=0.176\ifmmode\pm\else\textpm\fi{}0.008$ at a ${Q}^{2}$ value of 3 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ evaluated using ${\ensuremath{\alpha}}_{s}=0.32\ifmmode\pm\else\textpm\fi{}0.05$.

Published
1996
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3. Measurements of the Proton and Deuteron Spin Structure Functiong2and AsymmetryA2

Author

Y. Terrien, L.S. Rochester, T. L. Usher, J. Morgenstern, Donal Day, J. M. Bauer, R. A. Lindgren, D. Zimmermann, R. Prepost, K. A. Griffioen, H. R. Band, R. A. Gearhart, H. Borel, John C. Mitchell, C. Y. Prescott, T. Akagi, Y. Roblin, J. Gomez, H. Fonvieille, P. Grenier, E. W. Hughes, J. Button-Shafer, G. H. Zapalac, R. G. Arnold, J. Marroncle, D. Kawall, Jian-Ping Chen, T. Averett, W. Meyer, D. Walz, P. Raines, F. S. Dietrich, H. Yuta, C. E. Hyde-Wright, Timothy B. Smith, R. Pitthan, L. M. Stuart, K. Witte, P. E. Bosted, T. Maruyama, P.L. Anthony, Avraham Klein, Kevin P. Coulter, James L. White, J. Fellbaum, S.St. Lorant, D. Reyna, D. Garvey, B. Zihlmann, Emil Frlez, F. Staley, C. C. Young, T. J. Liu, M. Spengos, A. Rijllart, B. Raue, Z. M. Szalata, S. Hoibraten, R. Antonov, M. Kuriki, H. Dutz, J. A. Dunne, R. M. Lombard-Nelsen, Dinko Pocanic, K. Abe, Pascal Steiner, B. Youngman, X.K. Maruyama, L. C. Smith, O. Rondon, J. Clendenin, R. Erbacher, Z. E. Meziani, S. E. Kuhn, S. E. Rock, C. Comptour, G. G. Petratos, M. Daoudi, Ingo Sick, Timothy Chupp, J.R. Johnson, Vincent Breton, R. C. Minehart, A. Feltham, G.R. Court, D. G. Crabb, H. Tang, J. S. McCarthy, and F. Suekane

Subjects
Physics, Matrix (mathematics), Deuterium, Proton, Scattering, media_common.quotation_subject, General Physics and Astronomy, Electron, Atomic physics, Spin structure, Asymmetry, media_common, Spin-½
Abstract

We have measured proton and deuteron virtual photon-nucleon asymmetries A{sup p}{sub 2} and A{sup d}{sub 2} and structure functions g{sup p}{sub 2} and g{sup d}{sub 2} over the range 0.03 < x < 0.8 and 1.3 < Q{sup 2} < 10 (GeV/c){sup 2} by inelastically scattering polarized electrons off polarized ammonia targets. Results for A{sub 2} are significantly smaller than the positivity limit (sqrt)R for both targets. Within experimental precision the g{sub 2} data are well described by the twist-2 contribution, g{sup ww}{sub 2}. Twist-3 matrix elements have been extracted and are compared to theoretical predictions.

Published
1996
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4. Measurements of the Q2-dependence of the proton and deuteron spin structure functions g1 and g1

Author

A. Rijllart, J. Marroncle, Z. M. Szalata, J. Clendenin, T. Akagi, P. Raines, H. Dutz, T. J. Liu, Dinko Pocanic, H. R. Band, M. Kuriki, J. P. Chen, John C. Mitchell, S. E. Kuhn, B. Youngman, R. Prepost, S.St. Lorant, D. Walz, G. Court, Ingo Sick, Timothy B. Smith, J. Gomez, X.K. Maruyama, D. Kawall, K. Witte, L. M. Stuart, T. Maruyama, P. E. Bosted, P.L. Anthony, J. Fellbaum, C. Comptour, M. Daoudi, C. E. Hyde-Wright, R. Pitthan, D. Garvey, C. Y. Prescott, W. Meyer, Avraham Klein, R. A. Lindgren, G. G. Petratos, M. Spengos, F. Staley, L.S. Rochester, C. C. Young, T. L. Usher, B. Raue, S. Hoibraten, R. C. Minehart, D. Zimmermann, Pascal Steiner, H. Yuta, P. Grenier, K. A. Griffioen, Timothy Chupp, L. C. Smith, F. Suekane, J. Morgenstern, J. R. Johnson, G. H. Zapalac, Donal Day, Y. Roblin, D. G. Crabb, H. Tang, J. Button-Shafer, Koji Abe, J. A. Dunne, H. Fonvieille, H. Borel, J. S. McCarthy, F. S. Dietrich, T. Averett, R. G. Arnold, R. Erbacher, Z. E. Meziani, D. Reyna, R. A. Gearhart, A. Feltham, E. W. Hughes, J. L. White, J. M. Bauer, Vincent Breton, Kevin P. Coulter, O. Rondon, S. E. Rock, Y. Terrien, B. Zihlmann, Emil Frlez, R. Antonov, and R. M. Lombard-Nelsen

Subjects
Nuclear physics, Physics, High Energy Physics - Experiment (hep-ex), Nuclear and High Energy Physics, Deuterium, Proton, FOS: Physical sciences, Spin structure, High Energy Physics - Experiment
Abstract

The ratio g1/F1 has been measured over the range 0.031 (GeV/c)2. A trend is observed for g1/F1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g1/F1 are in agreement with the Bjorken sum rule, but Delta_q is substantially less than the quark-parton model expectation., Comment: 16 pages, format is postscript file, gzip-ed, uuencode-ed

Published
1995
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5. Evidence For Virtual Compton-Scattering From The Proton

Author

B. W. Filippone, Jenny Nelson, Kisoo Lee, Haiyan Gao, D. H. Potterveld, D. F. Geesaman, E. R. Kinney, H. E. Jackson, B. Zeidman, S. E. Rock, R. D. McKeown, K. van Bibber, B. Mueller, Michael Chapman, M. B. Epstein, K. P. Coulter, R. A. Gearhart, Jim Napolitano, Wolfgang Lorenzon, D. J. Margaziotis, J. Arrington, E. J. Beise, H. J. Bulten, P.L. Anthony, J.-O. Hansen, F. S. Dietrich, S. E. Kuhn, J. F. J. van den Brand, P. E. Bosted, G. G. Petratos, J. E. Belz, Thomas O'Neill, L. H. Tao, M. Spengos, Rolf Ent, V. Papavassiliou, Z. M. Szalata, A. Lung, D. A. Wasson, R. G. Arnold, C. E. Jones, C. E. Keppel, Ross Milner, James L. White, R. J. Holt, and Naomi C R Makins

Subjects
Physics, Photon, Proton, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Compton scattering, Electron, Compton wavelength, MAGNETIC FORM-FACTORS, Inelastic scattering, Q(2)=1.75, Linear particle accelerator, Nuclear physics, (GEV/C)(2), Physics::Accelerator Physics, Nucleon, Nuclear Experiment
Abstract

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation.

Published
1995
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6. Determination of the neutron spin structure function

Author

H. Fonvieille, E. W. Hughes, Y. Terrien, Sayed Rokni, Thomas E. Smith, P. E. Bosted, J. Xu, H. Borel, F. S. Dietrich, R. A. Gearhart, J. Fellbaum, P.L. Anthony, S. E. Rock, H. Middleton, M. Spengos, F. Staley, Nathan R. Newbury, R. G. Arnold, Vincent Breton, H. R. Band, Gordon D. Cates, R. Prepost, S. E. Kuhn, R. Erbacher, Gilbert Shapiro, J. A. Dunne, James L. White, M. Woods, Z. E. Meziani, G. G. Petratos, W. Meyer, Timothy Chupp, R. Holmes, G. H. Zapalac, J. Marroncle, J.R. Johnson, Z. M. Szalata, Paul Souder, C. E. Keppel, C. C. Young, R. Pitthan, R. M. Lombard-Nelsen, L. M. Stuart, D. Kawall, J. Morgenstern, T. Maruyama, Alan K. Thompson, Y. Roblin, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), E142, and Hughes V.W. Cavata C.

Subjects
Physics, Nuclear reaction, Particle physics, Proton, 010308 nuclear & particles physics, Hadron, General Physics and Astronomy, Elementary particle, Inelastic scattering, 01 natural sciences, 7. Clean energy, 0103 physical sciences, Proton spin crisis, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Sum rule in quantum mechanics, 010306 general physics, Nucleon
Abstract

The authors report the results of the experiment E142 which measured the spin dependent structure function of the neutron, g{sub 1}{sup n}(x, Q{sup 2}). The experiment was carried out at the Stanford Linear Accelerator Center by measuring an asymmetry in the deep inelastic scattering of polarized electrons from a polarized {sup 3}He target, at electron energies from 19 to 26 GeV. The structure function was determined over the kinematic range 0.03 < BJorken x < 0.6 and 1.0 < Q{sup 2} < 5.5 (GeV/c){sup 2}. An evaluation of the integral {integral}{sub 0}{sup 1} g{sub 1}{sup n}(x,Q{sup 2})dx at fixed Q{sup 2} = 2 (GeV/c){sup 2} yields the final result {Lambda}{sub 1}{sup n} = -0.032 {+-} 0.006 (stat.) {+-} 0.009 (syst.). This result, when combined with the integral of the proton spin structure function measured in other experiments, confirms the fundamental Bjorken sum rule with O({alpha}{sub s}{sup 3}) corrections to within one standard deviation. This is a major success for perturbative Quantum Chromodynamics. Some ancillary results include the findings that the Ellis-Jaffe sum rule for the neutron is violated at the 2 {sigma} level, and that the total contribution of the quarks to the helicity of the nucleon is 0.36 {+-}more » 0.10. The strange sea polarization is estimated to be small and negative, {Delta}s = -0.07 {+-} 0.04.« less

Published
1993
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7. Measurements of the nucleon form factors at large momentum transfers

Author

L. H. Tao, C. Hyde-Wright, R. Gearhart, C. E. Keppel, P. E. Bosted, L.M. Stuart, J. Alster, G. Petratos, J. Lichtenstadt, Stephen M. Rock, M. Spengos, R. S. Hicks, R. G. Arnold, C. C. Chang, G. A. Peterson, S. E. Kuhn, K. Swartz, K. Griffioen, A. Lung, L. Andivahis, F. Dietrich, Z. M. Szalata, J. Gomez, S. H. Rokni, W. R. Dodge, Sakumoto Wk, and R. Miskimen

Subjects
Momentum, Nuclear physics, Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Range (particle radiation), Dipole, Proton, Momentum transfer, Neutron, Nucleon
Abstract

New measurements of the electric GE(Q2) and magnetic GM(Q2) form factors of the nucleons are reported. The proton data cover the Q2 range from 1.75 to 8.83 (GeV/c)2 and the neutron data from 1.75 to 4.00 (GeV/c)2, more than doubling the range of previous data. Scaled by the dipole fit, GD(Q2), the results forGMp(Q2) /?pGD(Q2) decrease smoothly from 1.05 to 0.92, while GEp(Q2)/GD(Q2)is consistent with unity. The preliminary results for GMn(Q2) /?nGD(Q2) are consistent with unity, while GEn is consistent with zero at all values of Q2.

Published
1993
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8. Measurements of the electric and magnetic form factors of the proton fromQ2=1.75 to 8.83 (GeV/c)2

Author

P. E. Bosted, Sayed Rokni, J. Alster, M. Spengos, L. M. Stuart, K. A. Griffioen, L. Andivahis, R. G. Arnold, L. H. Tao, C. E. Hyde-Wright, Sakumoto Wk, W. R. Dodge, J. Lichtenstadt, A. Lung, Z. M. Szalata, F. S. Dietrich, S. E. Rock, J. Gomez, G. G. Petratos, R. S. Hicks, R. A. Gearhart, G. A. Peterson, C. C. Chang, K. Swartz, S. E. Kuhn, R. A. Miskimen, and C. E. Keppel

Subjects
Scattering cross-section, Physics, Particle physics, Particle properties, Proton, Particle model, Quark model, Hadron, Form factor (quantum field theory), General Physics and Astronomy, Elementary particle, Vector meson dominance, Baryon, Combinatorics, Crystallography, Neutron, Nucleon
Abstract

The proton elastic form factors ${\mathit{G}}_{\mathit{E}\mathit{p}}$(${\mathit{Q}}^{2}$) and ${\mathit{G}}_{\mathit{M}\mathit{p}}$(${\mathit{Q}}^{2}$) have been extracted for ${\mathit{Q}}^{2}$=1.75 to 8.83 (GeV/c${)}^{2}$ via a Rosenbluth separation to ep elastic cross section measurements in the angular range 13\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}\ensuremath{\theta}\ensuremath{\le}90\ifmmode^\circ\else\textdegree\fi{}. The ${\mathit{Q}}^{2}$ range covered more than doubles that of the existing data. For ${\mathit{Q}}^{2}$4 (GeV/c${)}^{2}$, where the data overlap with previous measurements, the total uncertainties have been reduced to 14% in ${\mathit{G}}_{\mathit{E}\mathit{p}}$ and 1.5% in ${\mathit{G}}_{\mathit{M}\mathit{p}}$. Results for ${\mathit{G}}_{\mathit{E}\mathit{p}}$(${\mathit{Q}}^{2}$) are consistent with the dipole fit ${\mathit{G}}_{\mathit{D}}$(${\mathit{Q}}^{2}$)=(1+${\mathit{Q}}^{2}$/0.71${)}^{\mathrm{\ensuremath{-}}2}$, while those for ${\mathit{G}}_{\mathit{M}\mathit{p}}$(${\mathit{Q}}^{2}$)/${\mathrm{\ensuremath{\mu}}}_{\mathit{p}}$${\mathit{G}}_{\mathit{D}}$(${\mathit{Q}}^{2}$) decrease smoothly from 1.05 to 0.92. Deviations from form factor scaling are observed up to 20%. The ratio ${\mathit{Q}}^{2}$${\mathit{F}}_{2}$/${\mathit{F}}_{1}$ is observed to approach a constant value for ${\mathit{Q}}^{2}$g3 (GeV/c${)}^{2}$. Comparisons are made to vector meson dominance, dimensional scaling, QCD sum rule, diquark, and constituent quark models, none of which fully characterize all the new data.

Published
1992
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9. Measurements of the proton and deuteron spin structure functionsg1andg2

Author

Timothy Chupp, R. Gearhart, S.St. Lorant, Koji Abe, D. Kawall, P. Raines, C. Y. Prescott, H. Fonvieille, F. S. Dietrich, L. S. Rochester, J. P. Chen, D. Crabb, M. Kuriki, Ch. Hyde-Wright, T. Averett, A. Rijllart, J. Clendenin, J. Morgenstern, Donal Day, L. C. Smith, R. C. Minehart, R. Erbacher, Z. E. Meziani, F. Staley, G. Court, B. Zihlmann, R. Prepost, Emil Frlez, J. R. Johnson, P. Grenier, Timothy B. Smith, Y. Roblin, R. Antonov, R. M. Lombard-Nelsen, C. C. Young, Avraham Klein, R. Pitthan, T. J. Liu, Dinko Pocanic, J. S. McCarthy, R. A. Lindgren, F. Suekane, G. G. Petratos, Ingo Sick, J. Fellbaum, J. Button-Shafer, H. Borel, K. A. Griffioen, S. E. Kuhn, K. Witte, John C. Mitchell, A. Feltham, E. W. Hughes, D. Walz, F.R. Wesselmann, P. E. Bosted, Z. M. Szalata, D. Garvey, J. M. Bauer, Y. Terrien, T. L. Usher, B. Raue, S. Hoibraten, Pascal Steiner, D. Zimmermann, Vincent Breton, H. R. Band, O. Rondon, H. Tang, K. P. Coulter, S. E. Rock, J. Gomez, R. G. Arnold, L. M. Stuart, T. Maruyama, D. Reyna, J. A. Dunne, X.K. Maruyama, C. Comptour, M. Daoudi, T. Akagi, M. Spengos, H. Yuta, P.L. Anthony, W. Meyer, G. H. Zapalac, H. Dutz, J. Marroncle, B. Youngman, and James L. White

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Proton, Deuterium, Full data, Zero (complex analysis), Resonance, Spin structure, Beam energy
Abstract

Measurements are reported of the proton and deuteron spin structure functions ${g}_{1}^{p}$ and ${g}_{1}^{d}$ at beam energies of 29.1, 16.2, and 9.7 GeV, and ${g}_{2}^{p}$ and ${g}_{2}^{d}$ at a beam energy of 29.1 GeV. The integrals ${\ensuremath{\Gamma}}_{p}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{p}{(x,Q}^{2})dx$ and ${\ensuremath{\Gamma}}_{d}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{d}{(x,Q}^{2})dx$ were evaluated at fixed ${Q}^{2}=3(\mathrm{GeV}{/c)}^{2}$ using the full data set to yield ${\ensuremath{\Gamma}}_{p}=0.132\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.009(\mathrm{syst})$ and ${\ensuremath{\Gamma}}_{d}=0.047\ifmmode\pm\else\textpm\fi{}0.003\ifmmode\pm\else\textpm\fi{}0.006.$ The ${Q}^{2}$ dependence of the ratio ${g}_{1}{/F}_{1}$ was studied and found to be small for ${Q}^{2}g1(\mathrm{GeV}{/c)}^{2}.$ Within experimental precision the ${g}_{2}$ data are well described by the twist-2 contribution, ${g}_{2}^{\mathrm{WW}}.$ Twist-3 matrix elements were extracted and compared to theoretical predictions. The asymmetry ${A}_{2}$ was measured and found to be significantly smaller than the positivity limit $\sqrt{R}$ for both proton and deuteron targets. ${A}_{2}^{p}$ is found to be positive and inconsistent with zero. Measurements of ${g}_{1}$ in the resonance region show strong variations with $x$ and ${Q}^{2},$ consistent with resonant amplitudes extracted from unpolarized data. These data allow us to study the ${Q}^{2}$ dependence of the integrals ${\ensuremath{\Gamma}}_{p}$ and ${\ensuremath{\Gamma}}_{n}$ below the scaling region.

Published
1998
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10. Measurements of theΔ(1232)transition form factor and the ratioσn/σpfrom inelastic electron-proton and electron-deuteron scattering

Author

P. E. Bosted, Sayed Rokni, R. A. Gearhart, M. Spengos, G. A. Peterson, K. Swartz, K. A. Griffioen, A. Lung, J. Lichtenstadt, S. E. Rock, S. E. Kuhn, L. Andivahis, R. G. Arnold, L. H. Tao, J. Gomez, W. R. Dodge, J. Alster, C. E. Hyde-Wright, L. M. Stuart, F. S. Dietrich, G. G. Petratos, Sakumoto Wk, R. S. Hicks, Z. M. Szalata, C. C. Chang, C. E. Keppel, and R. A. Miskimen

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Proton, Deuterium, Scattering, Form factor (quantum field theory), Resonance, Perturbative QCD, Production (computer science), Atomic physics, Deep inelastic scattering
Abstract

Measurements of inclusive electron-scattering cross sections using hydrogen and deuterium targets in the region of the $\ensuremath{\Delta}(1232)$ resonance are reported. A global fit to these new data and previous data in the resonance region is also reported for the proton. Transition form factors have been extracted from the proton cross sections for this experiment over the four-momentum transfer squared range $1.64l{Q}^{2}l6.75 (\mathrm{GeV}{/c)}^{2}$ and from previous data over the range $2.41l{Q}^{2}l9.82 (\mathrm{GeV}{/c)}^{2}.$ The results confirm previous reports that the $\ensuremath{\Delta}(1232)$ transition form factor decreases more rapidly with ${Q}^{2}$ than expected from perturbative QCD. The ratio of ${\ensuremath{\sigma}}_{n}/{\ensuremath{\sigma}}_{p}$ in the $\ensuremath{\Delta}(1232)$ resonance region has been extracted from the deuteron data for this experiment in the range $1.64l{Q}^{2}l3.75 (\mathrm{G}\mathrm{e}\mathrm{V}/{c)}^{2}$ and for a previous experiment in the range $2.4l{Q}^{2}l7.9 (\mathrm{GeV}{/c)}^{2}.$ A study has been made of the model dependence of these results. This ratio ${\ensuremath{\sigma}}_{n}/{\ensuremath{\sigma}}_{p}$ for $\ensuremath{\Delta}(1232)$ production is slightly less than unity, while ${\ensuremath{\sigma}}_{n}/{\ensuremath{\sigma}}_{p}$ for the nonresonant cross sections is approximately 0.5, which is consistent with deep inelastic scattering results.

Published
1998
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11. Determination of the Deep Inelastic Contribution to the generalised Gerasimov-Drell-Hearn Intregral for the Proton and Neutron

Author

K. Ackerstaff, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, S. Barrow, C. Baumgarten, M. Beckmann, S. Belostotski, J.E. Belz, T. Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, B. Bray, S. Brons, W. Brückner, A. Brüll, E.E.W. Bruins, H.J. Bulten, R. Cadman, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, G.R. Court, P.F. Dal Piaz, P.P.J. Delheij, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, H.T. Fortune, B. Fox, S. Frabetti, J. Franz, S. Frullani, M.-A. Funk, N.D. Gagunashvili, P. Galumian, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Gyurjyan, A. Golendoukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, C. Grosshauser, M.G. Guidal, A. Gute, J.P. Haas, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, F.H. Heinsius, R. Henderson, T. Henkes, M. Henoch, R. Hertenberger, Y. Holler, R.J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L.H. Kramer, B. Krause, V.G. Krivokhijine, M. Kückes, F. Kümmell, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N.C.R. Makins, S.I. Manaenkov, F.K. Martens, J.W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R.D. McKeown, F. Meissner, F. Menden, D. Mercer, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, M.A. Miller, R. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A.M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T.G. O'Neill, R. Openshaw, J. Ouyang, B. Owen, V. Papavassiliou, S.F. Pate, M. Pitt, H.R. Poolman, S. Potashov, D.H. Potterveld, G. Rakness, A. Reali, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, H. Roloff, G. Röper, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, F. Schmidt, H. Schmitt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, T.-A. Shibata, T. Shin, V. Shutov, M.C. Simani, A. Simon, K. Sinram, P. Slavich, W.R. Smythe, J. Sowinski, M. Spengos, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D.M. Thiessen, E. Thomas, B. Tipton, A. Trudel, M. Tytgat, G.M. Urciuoli, J.J. van Hunen, R. van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, M.C. Vetterli, M. Vincter, J. Visser, E. Volk, W. Wander, T.P. Welch, S.E. Williamson, T. Wise, K. Woller, S. Yoneyama, K. Zapfe-Düren, H. Zohrabian, R. Zurmühle, and (Astro)-Particles Physics

Subjects
Nuclear and High Energy Physics, Particle physics, Proton, Nuclear Theory, PARTON MODEL, Virtual particle, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, POLARIZED HE-3, SUM-RULES, Cross section (physics), High Energy Physics - Experiment (hep-ex), 0103 physical sciences, SCATTERING, Neutron, STRUCTURE-FUNCTION G(1)(N), 010306 general physics, Nuclear Experiment, NUCLEON, Quantum chromodynamics, Physics, 010308 nuclear & particles physics, Absorption cross section, Deep inelastic scattering, SPIN STRUCTURE-FUNCTION, RESONANCE REGION, High Energy Physics::Experiment, E-P, Nucleon
Abstract

The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2] for the proton and neutron have been determined from measurements of polarised cross section asymmetries in deep inelastic scattering of 27.5 GeV longitudinally polarised positrons from polarised 1H and 3He internal gas targets. The data were collected in the region above the nucleon resonances in the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the proton the contribution to the generalised Gerasimov-Drell-Hearn integral was found to be substantial and must be included for an accurate determination of the full integral. Furthermore the data are consistent with a QCD next-to-leading order fit based on previous deep inelastic scattering data. Therefore higher twist effects do not appear significant., 6 pages, 3 figures, 1 table, revtex

Published
1998
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12. The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering

Author

K. Ackerstaff, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, E. C. Ashenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, C. Baumgarten, M. Beckmann, St. Belostotski, J. E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, J. Brack, S. Brauksiepe, B. Braun, B. Bray, St. Brons, W. Brückner, A. Brüll, E. E. W. Bruins, H. J. Bulten, R. V. Cadman, G. P. Capitani, P. Carter, P. Chumney, E. Cisbani, G. R. Court, P. F. Dalpiaz, E. De Sanctis, D. De Schepper, E. Devitsin, P. K. A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, A. Fantoni, A. Fechtchenko, M. Ferstl, K. Fiedler, B. W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, M.-A. Funk, N. D. Gagunashvili, H. Gao, Y. Gärber, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, V. Giordjian, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Grosshauser, A. Gute, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, R. Henderson, Th. Henkes, M. Henoch, R. Hertenberger, Y. Holler, R. J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, V. Korotkov, W. Korsch, V. Kozlov, L. H. Kramer, V. G. Krivokhijine, M. Kurisuno, G. Kyle, W. Lachnit, W. Lorenzon, N. C. R. Makins, S. I. Manaenkov, F. K. Martens, J. W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R. D. McKeown, F. M. Menden, F. Meissner, A. Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, R. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A. M. Nathan, F. Neunreither, M. Niczyporuk, W.-D. Nowak, M. Nupieri, T. G. O'Neill, J. Ouyang, B. R. Owen, V. Papavassiliou, S. F. Pate, M. Pitt, S. Potashov, D. H. Potterveld, G. Rakness, A. Reali, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, H. Roloff, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, F. Schmidt, H. Schmitt, G. Schnell, K. P. Schüler, A. Schwind, T.-A. Shibata, K. Shibatani, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, M. Spengos, E. Steffens, J. Stenger, J. Stewart, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, B. Tipton, M. Tytgat, G. M. Urciuoli, J. J. van Hunen, R. van de Vyver, J. F. J. van den Brand, G. van der Steenhoven, M. C. Vetterli, M. G. Vincter, E. Volk, W. Wander, S. E. Williamson, T. Wise, K. Woller, S. Yoneyama, H. Zohrabian, and (Astro)-Particles Physics

Subjects
Quark, Particle physics, Proton, media_common.quotation_subject, High Energy Physics::Lattice, Nuclear Theory, General Physics and Astronomy, FOS: Physical sciences, PROTON, 01 natural sciences, 7. Clean energy, Asymmetry, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Pion, DRELL-YAN PROCESS, 0103 physical sciences, 010306 general physics, NUCLEON, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Deuterium, PARTON DISTRIBUTIONS, High Energy Physics::Experiment, Nucleon, BREAKING
Abstract

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02, Comment: 7 Pages, 2 figures, RevTeX format; slight revision in text, small change in extraction of dbar-ubar and comparison with a high q2 parameterization

Published
1998
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13. Measurement of Longitudinal Spin Transfer to Lambda Hyperons in Deep Inelastic Lepton Scattering

Author

Th. Benisch, H. E. Jackson, V. G. Krivokhijine, A. Nagaitsev, S. Bernreuther, T. A. Shibata, Haiyan Gao, C. Baumgarten, M. Amarian, B. Braun, Michel Vetterli, F. Menden, S. Brauksiepe, Andrey V. Izotov, R.O. Avakian, Evaristo Cisbani, G. Rakness, E. Devitsin, V. A. Kozlov, W.-D. Nowak, N. Akopov, A. Metz, Ralf Kaiser, M. Guidal, A. Reali, Valeria Muccifora, A.O. Mateos, B. D. Fox, A. R. Reolon, A. Avetissian, W. Lachnit, A. Airapetian, G. S. Kyle, V. A. Korotkov, M. Iodice, E. Steffens, M. Henoch, A. Kisselev, A. Borissov, Robert Henderson, M. Kurisuno, M. Sutter, G. M. Urciuoli, A. Simon, G. Gavrilov, M. Düren, R. D. McKeown, P. Geiger, R. J. Holt, G. P. Capitani, J. van Hunen, Klaus Rith, M. Kolstein, M. Ruh, Adel Terkulov, F. Masoli, J. Visser, A. Dvoredsky, L. G. Greeniaus, S. Yoneyama, R. Mussa, Wolfgang Lorenzon, B. Tipton, F. Neunreither, P. Carter, R. Openshaw, B. R. Owen, E. De Sanctis, C. Scarlett, H. Schmitt, H. Avakian, Y. Gärber, U. Stosslein, Y. Holler, Michael Tytgat, S. Taroian, P. Rossi, Salvatore Frullani, E. E. W. Bruins, A. Fechtchenko, B. Bray, Franco Garibaldi, P. F. Dalpiaz, K. Königsmann, R. P. Redwine, E. Thomas, Michael Pitt, A. Brüll, C. A. Miller, G. Schnell, W. Wander, J. Ely, A. Jgoun, G. Elbakian, A. Gute, W. Brückner, S. E. Williamson, S. Belostotski, P.K.A. de Witt Huberts, P. Kitching, Ross Milner, H. Kolster, O. Grebeniouk, S. I. Manaenkov, Alessandra Fantoni, T. Shin, M. Nupieri, G. van der Steenhoven, G. Graw, A. Golendukhin, H. J. Bulten, Alan M. Nathan, F.H. Heinsius, P. Chumney, E. C. Aschenauer, E. R. Kinney, V. Shutov, V. Vikhrov, B. Bains, L. H. Kramer, Wolfgang Korsch, Y. Naryshkin, C. Simani, Naomi C R Makins, F. Meissner, V. Gyurjyan, Manuella Vincter, M.-A. Funk, E. Volk, Ralf Hertenberger, H. Ihssen, J. P. Haas, A. Schwind, Hiroaki Kobayashi, K. Fiedler, K. Shibatani, K. Woller, M. Spengos, J. Franz, K. McIlhany, I.A. Savin, P.W. Green, G.R. Court, M. McAndrew, H. Tallini, J. W. Martin, S. Rudnitsky, Dirk Ryckbosch, Thomas O'Neill, K. P. Schüler, N. Koch, Nicola Bianchi, O. Mikloukho, S. Potashov, H. Zohrabian, M. Kirsch, P. Di Nezza, M. A. Miller, C. Grosshauser, R. A. Ristinen, J. M. Niczyporuk, N. Meyners, J.-O. Hansen, M. Ferstl, M. Bouwhuis, H. Böttcher, S. F. Pate, V. Papavassiliou, R. Van de Vyver, P. Slavich, Jeffrey Brack, J. Stenger, J. E. Belz, J. Stewart, W. Haeberli, P. Lenisa, J. Seibert, J. Wendland, D. Hasch, B. W. Filippone, J. Blouw, D. H. Potterveld, W. Hoprich, H. Fischer, O. Häusser, D. De Schepper, K. Sinram, T. Wise, V. Gharibyan, F. Schmidt, M. Beckmann, J. F. J. van den Brand, Yasuhiro Sakemi, Jinsong Ouyang, M. Hartig, S. Brons, F. K. Martens, and (Astro)-Particles Physics

Subjects
Photon, HERMES, (p pi-) [mass spectrum], PROTON, 01 natural sciences, polarization [up], High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 27.5 GeV, angular distribution, deep inelastic scattering [positron p], STRUCTURE-FUNCTION G(1)(P), NUCLEON, Nuclear Experiment, Physics, BARYONS, Spin polarization, HERA, Helicity, DESY HERA Stor, polarization [Lambda], +p+pi%22">Lambda --> p pi, Quark, fragmentation [up], Nuclear and High Energy Physics, Particle physics, electroproduction [Lambda], MUON SCATTERING, FOS: Physical sciences, Nuclear physics, ASYMMETRIES, 0103 physical sciences, ddc:530, SDG 7 - Affordable and Clean Energy, 010306 general physics, Z-DECAYS, quark model parton, 010308 nuclear & particles physics, Hyperon, (LAMBDA)OVER-BAR POLARIZATION, Deep inelastic scattering, conservation law [helicity], DEUTERON, High Energy Physics::Experiment, polarized beam [positron], +Lambda%22">positron p --> Lambda, POLARIZED QUARK DISTRIBUTIONS, Lepton, experimental results
Abstract

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the HERA storage ring. For an average fractional energy transfer = 0.45, the longitudinal spin transfer from the virtual photon to the Lambda has been extracted. The spin transfer along the Lambda momentum direction is found to be 0.11 +/- 0.17 (stat) +/- 0.03 (sys); similar values are found for other possible choices for the longitudinal spin direction of the Lambda. This result is the most precise value obtained to date from deep-inelastic scattering with charged lepton beams, and is sensitive to polarized up quark fragmentation to hyperon states. The experimental result is found to be in general agreement with various models of the Lambda spin content, and is consistent with the assumption of helicity conservation in the fragmentation process., Comment: 8 pages, 3 figures; new version has an expanded discussion and small format changes

Published
2001
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