The Q$^2$-Dependence of the Neutron Spin Structure Function g$_2^n$ at Low Q$^2$

Abstract : We present the first measurement of the Q^2-dependence of the neutron spin structure function g_2^n at five kinematic points covering 0.57 (GeV/c)^2 <= Q^2 <= 1.34 (GeV/c)^2 at x~0.2. Though the naive quark-parton model predicts g_2=0, non-zero values for g_2 occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses or orbital angular momentum. The sensitivity of g_2 to physics beyond the simple quark-parton model provides a unique opportunity to examine QCD dynamics in nucleon structure. When scattering occurs from a non-interacting quark, a prediction for g_2^n can be calculated using next-to-leading order fits to world data for g_1^n. Our results show a positive deviation from this prediction indicating that contributions such as quark-gluon interactions may be important. Data were also obtained for g_1^n and are consistent with a next-to-leading order fit to world data evolved to our kinematic range.
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http://hal.in2p3.fr/in2p3-00024256
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Submitted on : Wednesday, June 15, 2005 - 3:17:49 PM
Last modification on : Thursday, January 11, 2018 - 6:13:50 AM

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K. Kramer, D. Armstrong, T. Averett, W. Bertozzi, S. Binet, et al.. The Q$^2$-Dependence of the Neutron Spin Structure Function g$_2^n$ at Low Q$^2$. Physical Review Letters, American Physical Society, 2005, 95, pp.142002. ⟨10.1103/PhysRevLett.95.142002⟩. ⟨in2p3-00024256⟩

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