We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 0.7 < Q^2 < 20 GeV^2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets. Our measured g2 approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d2p and d2n are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x->0. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range. The absolute value of A2 is significantly smaller than the sqrt[R(1+A1)/2] limit.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 2.75 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 5.5 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 10.5 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets.The absolute value of A2 is significantly smaller than the sqrt{R} positivity limit over the measured range, while g2 is consistent with the twist-2 Wandzura-Wilczek calculation. We obtain results for the twist-3 reduced matrix elements d2p, d2d and d2n. The Burkhardt-Cottingham sum rule integral - int(g2(x)dx) is reported for the range 0.02 < x < 0.8.
2.75 degree spectrometer data.
5.5 degree spectrometer data.
10.5 degree spectrometer data.
The structure functions g1p and g1n have been measured over the range 0.014 < x < 0.9 and 1 < Q2 < 40 GeV2 using deep-inelastic scattering of 48 GeV longitudinally polarized electrons from polarized protons and deuterons. We find that the Q2 dependence of g1p (g1n) at fixed x is very similar to that of the spin-averaged structure function F1p (F1n). From a NLO QCD fit to all available data we find $\Gamma_1^p - \Gamma_1^n =0.176 \pm 0.003 \pm 0.007$ at Q2=5 GeV2, in agreement with the Bjorken sum rule prediction of 0.182 \pm 0.005.
Results for G1/F1 for the proton and neutron.
Results for G1/F1 for the proton and neutron.
Results for G1/F1 for the proton and neutron.
We report measurements of the asymmetry A_parallel for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified pions, were measured in the momentum range 10
The asymmetry for polarized photoproduction of inclusive hadrons from a polarized proton target. The errors are statistical only.
The asymmetry for polarized photoproduction of inclusive identified pions from a polarized proton target. The errors are statistical only.
The asymmetry for polarized photoproduction of inclusive hadrons from a polarized deuteron target. The errors are statistical only.
We have measured total cross sections for the reaction π+p→π+π−p at incident pion kinetic energies of 190, 200, 220, 240, and 260 MeV. We use this result to deduce a new value of the chiral symmetry breaking parameter, ξ=-0.25±0.10, in a global constrained fit of the five ππN near-threshold amplitudes. Consequently, we report new soft pion model values for the s-wave ππ scattering lengths.
No description provided.
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.
Averaged A1(P) for the DIS (W**2 > 4 GeV) region. Additional normalization uncertainty 3.7%.
Detailed A1(P) for the DIS (W**2 > 4 GeV) region. Additional normalization uncertainty 3.7%.
Detailed A1(P) for the DIS (W**2 > 4 GeV) region. Additional normalization uncertainty 3.7%.
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.
Extrapolation to the full x range was made using E154 data (see PL 405B, 180 and PRL 79, 26).
Measurments of g1/F1 and g1 using the 2.75 degree spectrometer.
Measurments of g1/F1 and g1 using the 5.5 degree spectrometer.
Measurements 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.
LOOP-OVER;.
The ratio g1/F1 has been measured over the range 0.03
No description provided.
No description provided.
No description provided.
We report on a high-statistics measurement of the deuteron spin structure function g1d at a beam energy of 29 GeV in the kinematic range 0.029
No description provided.
Values of G1 computed assuming G1/F1 is independent of Q**2 and evaluated at Q**2 = 3 GeV**2.
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