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Title: Measurement of the Tensor Structure Function b{sub 1} of the Deuteron

Abstract

The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A{sub zz}{sup d} and the tensor structure function b{sub 1}{sup d} for average values of the Bjorken variable 0.01<<x><0.45 and of the negative of the squared four-momentum transfer 0.5 GeV{sup 2}<<Q{sup 2}><5 GeV{sup 2}. The quantities A{sub zz}{sup d} and b{sub 1}{sup d} are found to be nonzero. The rise of b{sub 1}{sup d} for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2];  [3]; ; ; ; ; ; ; ;  [4] more »;  [5] « less
  1. Yerevan Physics Institute, 375036 Yerevan (Armenia)
  2. DESY, 15738 Zeuthen (Germany)
  3. (Armenia)
  4. Institute for High Energy Physics, Protvino, 142281 (Russian Federation)
  5. Department of Physics, University of Illinois, Urbana, Illinois 61801-3080 (United States) [and others
Publication Date:
OSTI Identifier:
20699668
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 95; Journal Issue: 24; Other Information: DOI: 10.1103/PhysRevLett.95.242001; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA). HERMES Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; DEEP INELASTIC SCATTERING; DESY; DEUTERONS; FOUR MOMENTUM TRANSFER; GEV RANGE 10-100; HERA STORAGE RING; POLARIZATION; POSITRON BEAMS; SPIN; STRUCTURE FUNCTIONS

Citation Formats

Airapetian, A., Akopov, N., Akopov, Z., Avakian, R., Avetissian, A., Elbakian, G., Gharibyan, V., Marukyan, H., Rostomyan, A., Taroian, S., Amarian, M., Yerevan Physics Institute, 375036 Yerevan, Ammosov, V.V., Bryzgalov, V., Gapienko, G., Gapienko, V., Ivanilov, A., Korotkov, V., Salomatin, Y., Tchuiko, B., and Andrus, A. Measurement of the Tensor Structure Function b{sub 1} of the Deuteron. United States: N. p., 2005. Web. doi:10.1103/PhysRevLett.95.242001.
Airapetian, A., Akopov, N., Akopov, Z., Avakian, R., Avetissian, A., Elbakian, G., Gharibyan, V., Marukyan, H., Rostomyan, A., Taroian, S., Amarian, M., Yerevan Physics Institute, 375036 Yerevan, Ammosov, V.V., Bryzgalov, V., Gapienko, G., Gapienko, V., Ivanilov, A., Korotkov, V., Salomatin, Y., Tchuiko, B., & Andrus, A. Measurement of the Tensor Structure Function b{sub 1} of the Deuteron. United States. doi:10.1103/PhysRevLett.95.242001.
Airapetian, A., Akopov, N., Akopov, Z., Avakian, R., Avetissian, A., Elbakian, G., Gharibyan, V., Marukyan, H., Rostomyan, A., Taroian, S., Amarian, M., Yerevan Physics Institute, 375036 Yerevan, Ammosov, V.V., Bryzgalov, V., Gapienko, G., Gapienko, V., Ivanilov, A., Korotkov, V., Salomatin, Y., Tchuiko, B., and Andrus, A. Fri . "Measurement of the Tensor Structure Function b{sub 1} of the Deuteron". United States. doi:10.1103/PhysRevLett.95.242001.
@article{osti_20699668,
title = {Measurement of the Tensor Structure Function b{sub 1} of the Deuteron},
author = {Airapetian, A. and Akopov, N. and Akopov, Z. and Avakian, R. and Avetissian, A. and Elbakian, G. and Gharibyan, V. and Marukyan, H. and Rostomyan, A. and Taroian, S. and Amarian, M. and Yerevan Physics Institute, 375036 Yerevan and Ammosov, V.V. and Bryzgalov, V. and Gapienko, G. and Gapienko, V. and Ivanilov, A. and Korotkov, V. and Salomatin, Y. and Tchuiko, B. and Andrus, A.},
abstractNote = {The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A{sub zz}{sup d} and the tensor structure function b{sub 1}{sup d} for average values of the Bjorken variable 0.01<<x><0.45 and of the negative of the squared four-momentum transfer 0.5 GeV{sup 2}<<Q{sup 2}><5 GeV{sup 2}. The quantities A{sub zz}{sup d} and b{sub 1}{sup d} are found to be nonzero. The rise of b{sub 1}{sup d} for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.},
doi = {10.1103/PhysRevLett.95.242001},
journal = {Physical Review Letters},
number = 24,
volume = 95,
place = {United States},
year = {Fri Dec 09 00:00:00 EST 2005},
month = {Fri Dec 09 00:00:00 EST 2005}
}
  • Precise results on the spin-dependent structure functions g{sub 1}{sup p}(x,Q{sup 2}) and g{sub 1}{sup d}(x,Q{sup 2}) over the kinematic range 0.0021 < x < 0.9 and 0.1 < Q2 < 20 GeV2 are presented. The analyses base on data collected at the HERMES experiment at DESY in polarized deep-inelastic scattering and make use of an unfolding algorithm in order to correct for radiation and detector smearing. Furthermore, final results of the first measurement of the tensor asymmetry Azz and the tensor structure function b{sub 1}{sup d}(x,Q{sup 2}) are provided.
  • New measurements are reported on the deuteron spin structure function g{sub 1}{sup d}. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q{sup 2} < 40 (GeV/c){sup 2}. These are the first high dose electron scattering data obtained using lithium deuteride ({sup 6}Li{sup 2}H) as the target material. Extrapolations of the data were performed to obtain moments of g{sub 1}{sup d}, including {Gamma}{sub 1}{sup d}, and the net quark polarization {Delta} {Sigma}.
  • We report on a high-statistics measurement of the deuteron spin structure function {ital g}{sup {ital d}}{sub 1} at a beam energy of 29 GeV in the kinematic range 0.029{lt}{ital x}{lt}0.8 and 1{lt}{ital Q}{sup 2}{lt}10 (GeV/{ital c}){sup 2}. The integral {Gamma}{sup {ital d}}{sub 1}={integral}{sup 1}{sub 0}{ital g}{sup {ital d}}{sub 1}{ital dx} evaluated at fixed {ital Q}{sup 2}=3 (GeV/{ital c}){sup 2} gives 0.042{plus_minus}0.003(stat){plus_minus}0.004(syst). Combining this result with our earlier measurement of {ital g}{sup {ital p}}{sub 1}, we find {Gamma}{sup {ital p}}{sub 1}{minus}{Gamma}{sup {ital n}}{sub 1}=0.163{plus_minus}0.010(stat){plus_minus}0.016(syst), which agrees with the prediction of the Bjorken sum rule with {ital O}({alpha}{sup 3}{sub {ital s}}) corrections,more » {Gamma}{sup {ital p}}{sub 1}{minus}{Gamma}{sup {ital n}}{sub 1}=0.171{plus_minus}0.008. We find the quark contribution to the proton helicity to be {Delta}{ital q}=0.30{plus_minus}0.06.« less
  • The experimental aspects and results of the recent SLAC E143 measurement of the deuteron spin structure function {ital g}{sup {ital d}}{sub 1} are discussed. These results are combined with the proton spin structure function, {ital g}{sup {ital p}}{sub 1}, obtained concurrently in the same experiment, to provide tests of the predictions of sum rules. The results are found to be in excellent agreement with the predictions of Bjorken while a significant disagreement is observed for Ellis-Jaffe. {copyright} {ital 1995 American Institute of Physics.}
  • Deep-inelastic scattering measurements were performed at SLAC with 29 GeV polarized electrons incident on longitudinally and transversely polarized deuterons to obtain the spin-dependent structure function g{sup d}{sub 1}. The high-statistics data cover the kinimatical range of x{sub B{sub j}} > 0.03 and 1 < Q{sup 2} < 10 GeV{sup 2}. The deuteron spin-structure function g{sup d}{sub 1} and the integral {integral}{sup 1}{sub 0} g{sup d}{sub 1}dx will be presented, as well as results for the fraction of nucleon helicity carried by quarks.