Nucleon and nuclear spin structure functions

Nuclear effects in polarized inelastic electron scattering off polarized $^3He$ are discussed; in the kinematics of future experiments at CEBAF, Fermi motion effects are found to be much larger than in deep inelastic scattering. It is shown that improperly describing nuclear dynamics would lead to the extraction of unreliable neutron spin structure functions. On the other hand side, a simple and workable equation relating the Gerasimov -- Drell -- Hearn Integral for the neutr...

Nuclear effects in Deep Inelastic Scattering of polarized electrons off polarized $^3$He are analyzed in terms of a spin dependent spectral function taking into account $S'$ and $D$ waves in $^3$He, as well as Fermi motion and binding effects. A simple and reliable equation relating the neutron and $^3$He spin structure functions is proposed.

It is shown that the nuclear effects playing a relevant role in Deep Inelastic Scattering of polarized electrons by polarized $^3$He are mainly those arising from the effective proton and neutron polarizations generated by the $S'$ and $D$ waves in $^3$He. A simple and reliable equation relating the neutron, $g_1^n$, and $^3$He, $g_1^3$, spin structure functions is proposed. It is shown that the measurement of the first moment of the $^3$He structure function can provide a si...

We present data on the inclusive scattering of polarized electrons from a polarized He-3 target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the resonance region, to the beginning of the deep inelastic regime, and were used to determine the spin difference in the virtual photoabsorption cross section. We extract the extended Gerasimov-Drell-Hearn integral for the neutron i...

The possibility of a reliable extraction of the neutron deep inelastic structure function, $F_2^n(x)$, for $ x < 0.85$ from joint measurements of deep inelastic structure functions of deuteron, $^{3}He$ and $^{3}H$ is investigated. The model dependence in this extraction, linked to the possible different interactions between nucleons in nuclei, is shown to be weak, if the nuclear structure effects are properly taken into account. A combined analysis of the deep inelastic stru...

We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei for polarization asymmetries, structure functions and their moments, both in the nucleon resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite Q^2 with the effective polarization ansatz often used in experimental data analyses, and explore the impact of \Delta\ components in the nuclear wave functio...

Nuclear effects in the spin-dependent structure function $g_1$ of the deuteron are studied in the kinematics of future experiments at CEBAF, ($\nu \leq 3~GeV, ~Q^2 \leq 2~GeV^2$). The magnitude of nuclear effects is found to be significantly larger than the one occurring in deep inelastic scattering ($\nu\to \infty, ~Q^2\to \infty$). A possibility to measure the neutron structure functions in the CEBAF experiments with deuterium is analysed. It is found that disregarding or i...

We present a comprehensive analysis of deep inelastic scattering from He-3 and H-3, focusing in particular on the extraction of the free neutron structure function, F_2^n. Nuclear corrections are shown to cancel to within 1-2% for the isospin-weighted ratio of He-3 to H-3 structure functions, which leads to more than an order of magnitude improvement in the current uncertainty on the neutron to proton ratio F_2^n/F_2^p at large x. Theoretical uncertainties originating from th...

The neutron longitudinal and transverse asymmetries $A^n_1$ and $A^n_2$ have been extracted from deep inelastic scattering of polarized electrons by a polarized $^3$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 $g^n_1 (x,Q^2)$ and $g^n_2(x,Q^2)$ over the range $0.03 < x < 0.6$ at an average $Q^2$ of 2 (GeV$/c)^2$. The data are used for the evaluation of the Ellis-Jaffe and Bjo...

Using recently derived relations between spin-dependent nuclear and nucleon g_1 and g_2 structure functions at finite Q^2, we study nuclear effects in 3He in the nucleon resonance and deep inelastic regions. Comparing the finite-Q^2 results with the standard convolution formulas obtained in the large-Q^2 limit, we find significant broadening of the effective nucleon momentum distribution functions, leading to additional suppression of the nuclear g_1 and g_2 structure functio...