The reaction e + p → e ′+ N ∗ was studied for four momentum transfers up to 2.34 (GeV/ c ) 2 in the region of the 1236 MeV isobar. An analysis of the data in terms of the cross sections σ T and σ L for the absorption of transverse and longitudinal photons is given for invariant masses of the final pion nucleon system W =1.220 GeV and W =1.350 GeV.
Total errors are presented.
Total errors are presented.
Total errors are presented.
The ratios of neutral-current to charged-current cross sections of v and v interactions, seperately, on proton and neutron targets have been measured. The Big European Bubble Chamber (BEBC), filled with deuterium and equipped with an external muon identifier (EMI) and an internal picket fence (IPF), was exposed to the CERN SPS (anti)neutrino wide-band beam. The measured ratios are R v p= = 0.405 ± 0.024 ± 0.021 , R v n = 0.243 ± 0.013 ± 0.016, R v p = 0.301 ± 0.027 ± 0.024 and R v n = 0.490 ± 0.050 ± 0.037 . (The first error is statistical and the second systematic). From combinations of these ratios the following neutral-current chiral coupling constants have been determined: u L 2 = 0.099 ± 0.018 ± 0.008, d L 2 = 0.202 ± 0.020 ± 0.019, u R 2 = 0.020 ± 0.016 ± 0.009 and d R 2 = 0.002 ± 0.017 ± 0.010. These results agree with the predictions of the SU(2) × U(1) standard electroweak model. Assuming ϱ = 1, the corresponding value of sin 2 θ w is found to be 0.247 ± 0.029, whereas a two-parameter fit to the data yields sin 2 θ w = 0.243 ± 0.046 and ϱ = 0.996 ± 0.041.
No description provided.
No description provided.
No description provided.
The cross-section ratio of neutral-current and charged-current semileptonic interactions of muon-neutrinos on isoscalar nuclei has been measured with the result:Rv=0.3093±0.0031 for hadronic energy larger than 4 GeV. From this ratio we determined the electroweak mixing angle sin2θW, wheremc is the charm-quark mass in GeV/c2. Comparison with direct measurements ofmw andmz determines the radiative shift of the intermediate boson mass Δr=0.077±0.025(exp.)±0.038(syst.), in agreement with the prediction. Assuming the validity of the electroweak standard theory we determined ϱ=0.990−0.013(mc−1.5)±0.009(exp.)±0.003(theor.).
No description provided.
No description provided.
STATISTICAL ERROR IN THE VALUE CITED IS REDUCING, WHEN CUT IS MORE STRINGENT?.
We have measured neutral and charged current interactions of ν μ and ν μ on proton and neutron. From a combination of ratios we determine the neutral current chiral coupling constants. The results are u 2 L = 0.13 ± 0.03, d 2 L = 0.19 ± 0.03, u 2 R = 0.02 ± 0.02 and d 2 R = 0.00 ± 0.02. These results agree with the predictions of the standard SU(2) × U(1) model. The corresponding value of sin 2 θ W is 0.20 ± 0.04.
No description provided.
No description provided.
No description provided.
Cross sections for ρ0 electroproduction measured in a streamer-chamber experiment are separated into elastic (ep→epρ0) and inelastic production channels. For the elastic channel, the total cross section and t dependence are presented. For the inelastic channel (1σ)dσdz, (1σ)dσdpT2, and a density matrix element are shown and compared to quark-parton-model predictions. The ratio of ρ0 to direct π0 production is found to be 2.0±0.5±0.3, where the first error is statistical, and the second error is systematic.
No description provided.
No description provided.
No description provided.
Measurements of inelastic electron scattering have been made in the range 2.2 < ν < 3.8 GeV and 0.1 < | Q 2 | < 0.3 (GeV/ c ) 2 , on a selection of nuclei ranging from hydrogen and deuterium to uranium, by measuring the scattered electron only. Detailed calculations have been made of the contribution of radiative tails to the measured yield. The results show a small ‘shadowing’ consistent with other electroproduction experiments, and also with photoproduction experiments in this ν range, but the shadowing decreases rapidly as | Q 2 | increases.
DEUTERIUM TO HYDROGEN CROSS SECTION RATIO (PER NUCLEON). FOR E(P=3) = 2.25 AND THETA = 8.5, THE RATIO IS 0.911 +- 0.037 (DSYS = 0.040).
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No description provided.
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