0000000000394113
AUTHOR
E.m. Kabuß
Measurement of the proton and deuteron structure functions, F2p and F2d, and of the ratio
The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q(2) < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The extracted values of the structure functions F-2(p) and F-2(d) are in good agreement with those from other experiments. The data cover a sufficient range of y to allow the determination of the ratio of the longitudinally to transversely polarised virtual photon absorption cross sections, R = sigma(L)/sigma(T), for 0.002 < x < 0.12. The …
Quark and gluon distributions and $\alpha_{s}$ from nucleon structure functions at low $x$
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.
Measurements of $R^{d}-R^{p}$ and $R^{Ca}-R^{C}$ 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 ...
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.
Longitudinal Spin Physics at COMPASS
Abstract The spin structure of the nucleon is studied by the COMPASS collaboration using scattering of muons off polarised protons and deuterons. From the resulting asymmetries spin structure functions are extracted and the flavour decomposition of the quark contribution to the nucleon spin is studied. The gluon polarisation is investigated using the photon–gluon fusion process. Here, two main channels are investigated, open charm production and high p T hadron pair production. Also first measurements of unpolarised cross sections are reported.