M.W. Krasny

Measurement of the proton elastic form factors for Q2=1−3(Gev/c)2☆

We report measurements of the proton form factors, G^p_E and G^p_M, extracted from elastic electron scattering in the range 1 ≤ Q^2 ≤ 3 (GeV/c)^2 with uncertainties of <15% in G^p_E and <3% in G^p_M. The results for G^p_E are somewhat larger than indicated by most theoretical parameterizations. The ratio of Pauli and Dirac form factors, Q^2(F^p_2/F^p_1), is lower in value and demonstrates less Q^2 dependence than these parameterizations have indicated. Comparisons are made to theoretical models, including those based on perturbative QCD, vector-meson dominance, QCD sum rules, and diquark constituents to the proton. A global extraction of the form factors, including previous elastic scattering measurements, is also presented.

Precision measurement of R=σL/σT and F2 in deep inelastic electron scattering

Abstract We report new results on a precision measurement of the ratio R= σ L / σ T , and the structure function F 2 , for deep inelastic electron-nucleon scattering in the range 0.2≤×≤0.5 and 1≤Q 2 ≤10 (GeV/c) 2 . Our results show, for the first time, a clear falloff of R with increasing Q 2 . Our R and F 2 results are in good agreement with QCD predictions only when corrections for target mass effects are included.

Measurement of R = σL/σT and F2 on Deuterium and Iron in Deep Inelastic Electron Scattering

We report new results on a precision measurement of the ratio R = σ L /σ T from deuterium, iron and gold targets, on the ratio σFe/σ D and on the structure function F 2, for deep inelastic electron-nucleus scattering in the range 0.2 < x < 0.5 and 1 ≤ Q 2 ≤ 10(GeV/c)2. We find no difference between R Fe and R d. Our results show, for first time, a clear falloff of R with increasing Q 2 at SLAC energies. Our R and F 2 results are in good agreement with QCD predictions only when corrections for target mass effects are included.

A study of the nuclear and kinematic dependence of R = σL/σT in deep inelastic electron scattering☆

Abstract We report preliminary results on the nuclear dependence of R = σL/σT in the deep inelastic electron scattering from deuterium, iron, and gold nuclei. In the x, Q2 range of 0.2 ⩽ x ⩽ 0.5 and 1 ⩽ Q2 ⩽ 5 (GeV/c)2, the average RFe − RD is 0.03 ± 0.02 (stat) ± 0.06 (syst); the final systematic errors are expected to be reduced to ± 0.03. The results indicate that there are no significant spin-0 constituents or higher twist effects in nuclei as compared to free nucleons. Models for the EMC effect with significant nuclear dependence of R are ruled out. The discrepancy, at low x, between CERN and SLAC results for the cross section ratio σFe/σD cannot be attributed to a nuclear dependence of R as suggested by some authors. The kinematic variation of RD with x and Q2 in the SLAC energy is in agreement with the predictions of QCD with the addition of target mass effects.

Precision measurement of R=σL/σT and F2 in deep inelastic electron scattering on deuterium and iron targets

We report new results on a precision measurement of the ratio R=σL/σT from deuterium, iron and gold targets, on the ratio σFe/σD and on the structure function F2, for deep inelastic electron‐nucleus scattering in the range 0.2≤x≤0.5 and 1≤Q2≤10(GeV/c)2. We find no difference between RFe and Rd. Our results show, for first time, a clear falloff of R with increasing Q2 at SLAC energies. Our R and F2 results are in good agreement with QCD predictions only when corrections for target mass effects are included.