Proton spin content and QCD topological susceptibility

quarks is calculated in the framework of the QCD sum rules in the external fields. The operators up to dimension 9 are accounted. An important contribution comes from the operator of dimension 3, which in the limit of massless

u, d, s

quarks is equal to the derivative of QCD topological susceptibility

\chi^{\prime} (0)

. The comparison with the experimental data on

\Sigma

gives

\chi^{\prime}(0)= (2.3 \pm 0.6) \times 10^{-3} ~ GeV^2

. The limits on

\Sigma

and

\chi^{\prime}(0)

are found from selfconsistency of the sum rule, \Sigma \ga 0.05,~~ \chi^{\prime} (0) \ga 1.6 \times 10^{-3} ~ GeV^2. The values of

g_A = 1.37 \pm 0.10

and

g^8_A = 0.65 \pm 0.15

are also determined.

p: spin
quark: spin
quantum chromodynamics: susceptibility
sum rule: external field
operator product expansion
operator: dimension
numerical calculations

References(19)

Figures(0)

Spin structure of the proton from polarized inclusive deep inelastic muon - proton scattering

Spin Muon (SMC)

Collaboration

•

D. Adams

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e-Print:
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DOI:
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Next-to-leading order QCD analysis of polarized deep inelastic scattering data

E154

Collaboration

•

K. Abe
(
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)

et al.

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e-Print:
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•
DOI:
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•
DOI:
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Divergence of the operator product expansion in the singlet axial channel and the proton spin content

B.L. Ioffe
(
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,
A.Yu. Khodjamirian
(
- Yerevan Phys. Inst.
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V.M. Belyaev
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,
Ya.I. Kogan
(
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