P. Amaudruz

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 ratio F2n/F2p in deep inelastic muon scattering

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.

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

We present the structure function ratiosF2He/F2D,F2C/F2D andF2Ca/F2D measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. The kinematic range 0.0035<x<0.65 and 0.5<Q2<90 GeV2 is covered. At lowx the three ratios are significantly smaller than unity and the size of the depletion grows with decreasingx and increasing mass numberA. At intermediatex the ratios show an enhancement of about 2% above unity for C/D and Ca/D, possibly less for He/D. There are indications of someQ2 dependence in the Ca/D data. The integrals of the structure function differencesF2A−F2D are discussed.

Measurement of the neutron and the proton F2 structure function ratio

The ratio of the structure function F2n/F2p (x) has been measured in deep inelastic scattering of 274 GeV muons on hydrogen and deuterium targets exposed simultaneously to the beam. The results were obtained from 0.3 (0.6) million events from hydrogen (deuterium) in the range 0.004 <x< 0.8 and 1 <Q2< 190 GeV2. At x < 0.25 both the statistical and the systematic error is below 2%. Implications for parton distributions and for the σw/σz production cross section ratio in pp collisions are discussed. When compared to other results obtained at lower energies, the data indicate a Q2 dependence of the ratio.

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

We present results on J/ψ production in muon interactions with tin and carbon targets at incident muon energies of 200 and 280 GeV. The ratio of cross sections per nucleon for J/ψ production on tin and carbon, R(Sn/C), is studied as a function of pT2, z and x. We find an enhancement for coherent J/ψ production Rcoh(Sn/C) = 1.54 ± 0.07, a suppression for quasielastic production Rqe(Sn/C) = 0.79 ± 0.06 and for inelastic production Rin(Sn/C) = 1.13 ± 0.08. The inelastic cross section ratio can be interpreted within the Colour Singlet model as an enhancement of the gluon distribution in tin with respect to that in carbon. The dependence of the ratio on z and pT2 can explain the discrepancy between the results obtained in previous experiments.

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

Results are presented on the difference in R, the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, for the deuteron and the proton. They are obtained by c ...

Transverse momentum distributions for exclusiveρ0 muoproduction

We have studied transverse momentum distributions for exclusiveρ0 muoproduction on protons and heavier nuclei at 2<Q2<25 GeV2. TheQ2 dependence of the slopes of thept2 andt′ distributions is discussed. The influence of the non-exclusive background is investigated. Thept2-slope for exclusive events is 4.3±0.6±0.7 GeV−2 at largeQ2. Thept2 spectra are much softer than inclusivept2 spectra of leading hadrons produced in deep inelastic scattering.

Precision-measurement of Structure-function Ratios For Li-6, C-12 and Ca-40

The structure function ratiosF2C/F2Li,F2Ca/F2Li andF2Ca/F2C were measured in deep inelastic muonnucleus scattering at an incident muon energy of 90 GeV, covering the kinematic range 0.0085<x<0.6 and 0.8<Q2<17GeV2. The sensitivity of the nuclear structure functions to the size and mean density of the target nucleus is discussed.

The Ratio F2(n)/f2(p) In Deep Inelastic Muon Scattering

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.

The ratio

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.