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Deep-Inelastic Inclusive ep Scattering at Low x and a Measurement of alpha_s |
| Reference |
F. Zomer, talk presented at ICHEP 2000, July 2000 |
| Document |
Conference paper
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| Contact |
Max Klein, Vladimir Shekelyan, Rainer Wallny |
| Abstract |
A precise measurement at HERA of the inclusive deep-inelastic e^+p scattering cross section is reported for four-momentum transfers squared 1.5<=Q^2<=150 GeV^2 and Bjorken-x values $3*10^(-5)<=x<=0.2$ using new instrumentation in the backward region of the H1 detector. In most of this kinematic range the cross section sigma is determined to good approximation by the proton structure function F2. At intermediate Q^2 and large x, the data confirms the measurements of previous fixed target muon-proton scattering experiments. At smallest x, the longitudinal structure function FL is determined. The behaviour of the measured cross section and of the derivatives, dsigma / dln y and dF_2 / dln Q^2, is in accord with perturbative Quantum Chromodynamics. In a DGLAP QCD fit to H1 ep and BCDMS mu p inclusive cross section data, the gluon momentum distribution xg(x) and the strong interaction coupling constant alphas are determined simultaneously. A value of alphas(MZ) = 0.1150+-0.0017(exp)+0.0011-0.0012(model) is obtained in next-to-leading order QCD with an extra theoretical error of about +-0.005 due to renormalisation scale uncertainties. |
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