M. de Jong

Proton and deuteron F2 structure functions in deep inelastic muon scattering

The structure functions F2p and F2d measured by deep inelastic muon scattering at incident energies of 90 and 280 GeV are presented. These measurements cover a large kinematic range, 0.006 less-tha ...

The Structure Function ratios F2(li) / F2(D) and F2(C) / F2(D) at small x

We present the structure function ratios F2(Li)/F2(D) and F2(C)/F2(D) measured in deep inelastic muon-nucleus scattering at a nominal incident muon energy of 200 GeV. The kinematic range 0.0001 s x s 0.7 and 0.01 s Q˜2 s 70 GeV˜2 is covered. For values of

Knockout of 1p protons from 12C induced by the (e, e'p) reaction

x

Exclusive ϱ0 and φ muoproduction at large Q2

less than

The ratio F2n/F2p in deep inelastic muon scattering

0.002

Quark and gluon distributions and αs from nucleon structure functions at low x

both ratios indicate saturation of shadowing at values compatible with photoabsorption results.

Precision measurement of the structure function ratiosF 2 He /F 2 D ,F 2 C /F 2 D andF 2 Ca /F 2 D

Abstract The reaction 12 C(e, ep) 11 B has been studied in parallel kinematics at an outgoing-proton energy of 70 MeV. The momentum distributions for 1p knockout measured in the range of missing momentum −170 ⩽ p m ⩽ 210 MeV/ c are compared to DWIA calculations employing various prescriptions for the final-state interaction. It is found impossible to obtain simultaneously a good description of the data at positive p m , and negative p m , using a standard DWIA calculation. This discrepancy can be resolved by assuming a (15 ± 5)% enhancement of the ratio of transverse to longitudinal response functions. The effects of channel couplings in the final state of the (e, ep) reaction have been investigated by performing CCIA calculations with a coupling scheme derived from elastic proton scattering off 12 C. In elastic proton scattering an adjustment of the optical potential causes the standard optical-model calculation to be almost equivalent to the coupled-channels calculation. Similar calculations for the (e, ep) reaction yield momentum distributions that differ from the DWIA calculations, especially in parallel kinematics. The influence of the channel couplings on the derived spectroscopic factors is relatively small for the ground state (≈1%), but can be as large as 30% for the excited states. We find a spectroscopic strength for 1p knockout from 12 C of (57 ± 6)% of the IPSM sum-rule assuming that the longitudinal part of the virtual-photon proton coupling is not modified. The rms radii of the proton 1p orbitals as deduced from the measured momentum distributions are consistent with those derived from elastic magnetic electron scattering.

Measurement of the neutron and the proton F2 structure function ratio

Abstract Exclusive ϱ0 and φ muoproduction on deuterium, carbon and calcium has been studied in the kinematic range 2

Ratio of J/Psi production cross sections in deep inelastic muon scattering from tin and carbon

Results are presented on the ratio of neutron and proton structure functions, F2n/F2p, deduced from deep inelastic scattering of muon from hydrogen and deuterium. The data, which were obtained at the CERN muon beam at 90 and 280 GeV incident energy, cover the kinematic range x = 0.002−0.80 and Q2 = 0.1−190 GeV2. The measured structure function ratios have small statistical and systematic errors, particularly at small and intermediate x. The observed Q2 dependence in the range x = 0.1−0.4 is stronger than predicted by perturbative QCD. From the present data together with results from other experiments it is suggested that the twist-four coefficient for the proton is smaller than that for the neutron for x larger than 0.2.

Measurements of Rd-Rp and RCa-Rc in deep inelastic muon scattering

Abstract The Q2 dependence of the structure functions F2p and F2d recently measured by the NMC is compared with the predictions of perturbative QCD at next-to-leading order. Good agreement is observed, leading to accurate determinations of the quark and gluon distributions in the range 0.008 ⩽ × ⩽ 0.5. The strong coupling constant is measured from the low x data; the result agrees with previous determinations.