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NORMALISATION UNCERTAINTY IS 7 PCT.
NORMALISATION UNCERTAINTY IS 7 PCT.
A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and theirQ2 evolution is compared with the predictions of quantum chromodynamics.
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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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Structure functions obtained from high energy neutrino and antineutrino scattering from an iron target are presented. These were extracted from the combined data of Fermilab experiments E616 and E701; these utilized narrow band beam runs between 1979–1982. The structure functions are used to test the validity of quarkparton model (QPM) predictions and to extract the QCD scale parameter Λ from fits to the Altarelli-Parisi equations.
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We present results on a high statistics study of the nucleon structure functions F 2 ( x , Q 2 ) and R = σ L / σ T measured in deep inelastic scattering of muons on a deuterium target. The analysis is based on 8×10 5 events after all cuts, recorded at beam energies of 120, 200 and 280 GeV in the kinematic range 0.06⩽ × ⩽0.80 and 8GeV 2 ⩽ Q 2 ⩽260GeV 2 . Scaling violations observed in the data are in agreement with predictions of perturbative QCD and allow to determine the QCD mass scale parameter Λ.
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R=SIG(L)/SIG(T) is taken to be zero.
R=SIG(L)/SIG(T) is taken to be zero.
After completion of the data taking for the νμ→ντ oscillation search, the CHORUS lead–scintillator calorimeter was used in the 1998 run as an active target. High-statistics samples of charged-current interactions were collected in the CERN SPS west area neutrino beam. This beam contained predominantly muon (anti-)neutrinos from sign-selected pions and kaons. We measure the flux and energy spectrum of the incident neutrinos and compare them with beam simulations. The neutrino–nucleon and anti-neutrino–nucleon differential cross-sections are measured in the range 0.01<x<0.7 , 0.05<y<0.95 , 10<Eν<200 GeV . We extract the neutrino–nucleon structure functions F2(x,Q2) , xF3(x,Q2) , and R(x,Q2) and compare these with results from other experiments.
The measured F2 and xF3 at X = 0.020.
The measured F2 and xF3 at X = 0.045.
The measured F2 and xF3 at X = 0.080.
The inclusive production of D*+- mesons in photon-photon collisions has been measured using the OPAL detector at LEP at e+e- centre-of-mass energies of 183 and 189GeV. The D* mesons are reconstructed in their decay to D0pi+ with the D0 observed in the two decay modes Kpi+ and Kpi+pi-pi+. After background subtraction, 100.4+-12.6(stat) D*+- mesons have been selected in events without observed scattered beam electron ("anti-tagged") and 29.8+-5.9 (stat) D*+- mesons in events where one beam electron is scattered into the detector ("single-tagged"). Direct and single-resolved events are studied separately. Differential cross-sections as functions of the D* transverse momentum p_t and pseudorapidity \eta are presented in the kinematic region 2<p_t<12GeV and \eta<1.5. They are compared to next-to-leading order (NLO) perturbative QCD calculations. The total cross-section for the process (e+e- to e+e-ccbar), where the charm quarks are produced in the collision of two quasi-real photons, is measured to be 842+-97(stat)+-75(syst)+-196(extrapolation)pb. A first measurement of the charm structure function F2 of the photon is performed in the kinematic range 0.0014<x<0.87 and 5<Q^2<100 GeV^2, and the result is compared to a NLO perturbative QCD calculation.
Differential PT distribution for anti-tagged events for both D* decay modesand combined.
Differential ETARAP distribution for anti-tagged events for both D* decay modes and combined.
Integrated cross section using the anti-tagged events for D* production in the kinematic range of the experiment.
We present results from a high statistics study of the nucleon structure function F 2 ( x , Q 2 ) measured in deep inelastic scattering of muons on carbon in the kinematic range 0.25⩽ x ⩽0.80 and Q 2 ⩾25 GeV 2 . The analysis is based on 1.5×10 6 reconstructed events recorded at beam energies of 120, 200 and 280 GeV. R = σ L / σ T is found to be independent of x in the range 0.25⩽ x ⩽0.07 and 40 GeV 2 ⩽ Q 2 ⩽200 GeV 2 with a mean value R =0.015±0.013 ( stat ) ±0.026 (syst.).
R=SIG(L)/SIG(T).
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