J. Gomez

Measurements of the Proton and Deuteron Spin Structure Functions g1 and g2

Measurements are reported of the proton and deuteron spin structure functions g1 at beam energies of 29.1, 16.2, and 9.7 GeV and g2 at a beam energy of 29.1 GeV. The integrals of g1 over x have been evaluated at fixed Q**2 = 3 (GeV/c)**2 using the full data set. The Q**2 dependence of the ratio g1/F1 was studied and found to be small for Q**2>1 (GeV/c)**2. Within experimental precision the g2 data are well-described by the Wandzura-Wilczek twist-2 contribution. Twist-3 matrix elements were extracted and compared to theoretical predictions. The asymmetry A2 was measured and found to be significantly smaller than the positivity limit for both proton and deuteron targets. A2 for the proton is found to be positive and inconsistent with zero. Measurements of g1 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 first moments of g1 below the scaling region.

Measurements of the Q**2 dependence of the proton and neutron spin structure functions g(1)**p and g(1)**n

Abstract The ratio g 1 F 1 has been measured over the range 0.03 g 1 F 1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q2 > 1 (GeV/c)2. A trend is observed for g 1 F 1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g 1 F 1 are in agreement with the Bjorken sum rule, but Δq is substantially less than the quark-parton model expectation.

Measurement of the deuteron spin structure function g1d(x) for 1 (GeV/c)2 < Q2 < 40 (GeV/c)2

New measurements are reported on the deuteron spin structure function g_1^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^2<40 (GeV/c)^2. These are the first high dose electron scattering data obtained using lithium deuteride (6Li2H) as the target material. Extrapolations of the data were performed to obtain moments of g_1^d, including Gamma_1^d, and the net quark polarization Delta Sigma.Abstract New measurements are reported on the deuteron spin structure function g1d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 6 Li 2 H) as the target material. Extrapolations of the data were performed to obtain moments of g1d, including Γ1d, and the net quark polarization ΔΣ.

Measurement of the Neutral Weak Form Factors of the Proton

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point [{l_angle}{theta}{sub lab }{r_angle}=12.3{degree} and {l_angle}Q{sup 2}{r_angle}=0.48 (GeV /c){sup 2} ] is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor G{sup s}{sub E} . The result, A={minus}14.5{plus_minus}2.2 ppm , is consistent with the electroweak standard model and no additional contributions from strange quarks. In particular, the measurement implies G{sup s}{sub E}+0.39G{sup s}{sub M}=0.023 {plus_minus}0.034(stat){plus_minus}0.022( syst){plus_minus}0.026({delta}G{sup n}{sub E}) , where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor. {copyright} {ital 1999} {ital The American Physical Society}

Measurements of R = σL/σT for 0.03 < x < 0.1 and Fit to World Data

Abstract Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5°, corresponding to 0.03Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5 degrees, corresponding to 0.03<x<0.1 and 1.3<Q^2<2.7 GeV^2. Values of R=sigma_L/sigma_T were extracted in this kinematic range by comparing these data to cross sections measured at a higher beam energy by the NMC collaboration. The results are in reasonable agreement with pQCD calculations and with extrapolations of the R1990 parameterization of previous data. A new fit is made including these data and other recent results.

Precision Measurement of the Neutron Spin Asymmetries and Spin-dependent Structure Functions in the Valence Quark Region

We report on measurements of the neutron spin asymmetries

Short Range Correlations and the EMC Effect

A_{1,2}^n

Final analysis of proton form factor ratio data at Q2 = 4.0, 4.8, and 5.6 GeV2

and polarized structure functions

Precision Measurement of the Neutron Spin Asymmetry A1 n and Spin-Flavor Decomposition in the Valence Quark Region

g_{1,2}^n

Proton G_E/G_M from beam-target asymmetry

at three kinematics in the deep inelastic region, with