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.
Overall normalization error of 0.7%, due to uncertainties in target thickness, not included in the table.
Overall normalization error of 0.8%, due to uncertainties in target thickness, not included in the table.
Overall normalization error of 0.5%, due to uncertainties in target thickness, not included in the table.
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.
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Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio F2n/F2p in the kinematic range 0.004<x<0.8 and 0.4<Q2<190 GeV2, together with the structure function F2d determined from a fit to published data, are used to derive the difference F2p(x)-F2n(x). The value of the Gottfried sum F(F2p-F2n)dx/x=0.240±0.016 is below the quark-parton-model expectation of 1/3.
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The ratio of the structure function F 2 n / F 2 p ( 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 < Q 2 < 190 GeV 2 . At x < 0.25 both the statistical and the systematic error is below 2%. Implications for parton distributions and for the σ w / σ z production cross section ratio in p p collisions are discussed. When compared to other results obtained at lower energies, the data indicate a Q 2 dependence of the ratio.
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Small angle scattering of 280 GeV positive muons by deuterium, carbon and calcium has been measured at scattering angles down to 2 mrad. The nucleon structure function F 2 extracted from deuterium does not show a significant x dependence in the measured range of Q 2 and its Q 2 dependence is linear in log Q 2 . For calcium, a depletion of F 2 is observed at low x by 30% as compared with the values at x = 0.1 where F 2 (Ca) and F 2 (D) are not significantly different. This depletion is attributed to shadowing. The carbon structure function exhibits a similar, but less pronounced, x dependence. Such behaviour is observed to be independent of Q 2 . The data are consistent with those obtained from other charged lepton experiments both at similar and higher values of x and Q 2 and considerably extend the range of the measurements down to the low values of x to be measured in forthcoming experiments at HERA.
Deuterium data. Overall normalization error of 7 pct not included.
Deuterium data. Overall normalization error of 7 pct not included.
Deuterium data. Overall normalization error of 7 pct not included.
Using the CHARM detector 36 000 deep inelastic neutral-current reactions of neutrinos (and 2000 of antineutrinos) from the 160 GeV narrow-band beam were recorded. The differential cross section d σ d x in the Bjorken scaling variable x was computed by unfolding the effects of limited acceptance and of resolution of the detector as well as the ambiguity of the energy of the incoming neutrinos (produced by π- or K-decay). Combining the results from the neutrino and antineutrino data, the structure functions F 2 and xF 3 and the antiquark momentum distribution measured via the NC coupling were determined. The distributions are in agreement with the corresponding CC distibutions. Comparisons with deep inelastic muon scattering confirm the universality of nuclear structure functions as probed by the weak and the electromagnetic currents.
SEE THE PAPER FOR THE PRECISE DEFNS OF F(+), F(-).
Results are presented on the ratios of the deep inelastic muon-nucleus cross sections for carbon, copper and tin nuclei to those measured on deuterium. The data confirm that the structure functions of the nucleon measured in nuclei are different from those measured on quasi-free nucleons in deuterium. The kinematic range of the data is such that 〈 Q 2 〉 ∼ 5 GeV 2 at x ∼ 0.03, increasing to 〈 Q 2 〉 ∼ 35 GeV 2 for x ∼ 0.65. The measured cross section ratios are less than unity for x ≲ 0.05 and for 0.25 ≲ x < 0.7. The decrease of the ratio below unity for low x becomes larger as A increases as might be expected from nuclear shadowing. However, this occurs at relatively large values of Q 2 (∼ 5 GeV 2 ) indicating that such shadowing is of patrionic origin.
Q**2= 5.1,7.8,11.4,14.4,17.3,20.2,24.1,29.8,33.6 GEV**2.
Q**2= 4.4,8.4,13.5,17.9,21.1,24.4,29.5,34.0,40.4 GEV**2.
Q**2= 4.0,7.7,11.1,14.6,17.1,19.8,24.8,32.4 GEV**2.
The isoscalar nucleon structure functionsF2(x, Q2) andxF3(x, Q2) are measured in the range 0<Q2<64 GeV2, 1.7<W2<250 GeV2,x<0.7 using ν and\(\bar v\) interactions on neon in BEBC. The data are used to evaluate possible higher twist contributions and to determine their impact on the evaluation of the QCD parameter Λ. In contrast to previous analyses reaching to such lowW2 values, it is found that a low\(\Lambda _{\overline {MS} } \) value in the neighbourhood of 100 MeV describes the data adequately and that the contribution of dynamical higher twist effects is small and negative.
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We present a measurement of the photon structure functionF2γ in the reactionee→eeX forQ2 in the range 0.2<Q2<7 GeV2, using 9,200 multihadron events obtained with the TPC/Two-Gamma detector at PEP. The data have been corrected for detector effects using a regularized unfolding procedure and are presented as a function ofx andQ2. The structure function shows scaling in the region 0.3<Q2<1.6 GeV2,x<0.3 and rises for higherQ2. AtQ2=5.1 GeV2 the results are compared with QCD and, within the scheme of Antoniadis and Grunberg, rather conservative bounds for the QCD scale parameter of 133±50<\(\Lambda _{\overline {{\rm M}S} } \)<268±98 MeV are obtained. A study of the final state structure shows that the rise ofF2γ is consistent with being entirely due to the pointlike component of the photon.
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The energy distribution of inclusive hadrons produced by 280 GeV muons on hydrogen and deuterium targets are compared. The sum of the scaled energy distributions of the positive and negative hadrons is found to be the same for the two targets. The difference of these distributions is observed to factorise inx andz and thez-dependence is found to be independent of the target type and have a form (1−z)2.1±0.2. The net charge of the hadronic jet is positive at highx even in the case when the scattering takes place on the neutron. These results are in good agreement with the expectations of the Quark Parton Model.
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