A precise measurement of the atomic-mass dependence of dimuon production induced by 800-GeV protons is reported. Over 450 000 muon pairs with dimuon mass M≥4 GeV were recorded from targets of H2, C, Ca, Fe, and W. The ratio of dimuon yield per nucleon for nuclei versus H2, R=YA/Y2H, is sensitive to modifications of the antiquark sea in nuclei. No nuclear dependence of this ratio is observed over the range of target-quark momentum fraction 0.1<xt<0.3. For xt<0.1 the ratio is slightly less than unity for the heavy nuclei. These results are compared with predictions of models of the European Muon Collaboration effect.
High Mass trigger data.
Intermediate Mass trigger data.
Low Mass trigger data.
Measurements of the cross section for production of massive dihadrons by 800-GeV protons incident on a tungsten target are presented. These are compared with measurements taken at lower and higher s and with perturbative-QCD predictions. Scaling and A-dependence behaviors observed at lower energies are confirmed, and good agreement with QCD is obtained. Model dependences of earlier measurements are discussed.
No description provided.
Triple differential cross section. Note that the errors plotted in the original figure are 2 time too large. The numbers given here are correct.
500 MeV p→+p elastic and quasielastic, and p→+n quasielastic, analyzing powers (Ay) and spin-rotation-depolarization parameters (DSS, DSL, DLS, DLL, DNN) were determined for center-of-momentum angular ranges 6.8°–55.4° (elastic) and 22.4°–55.4° (quasielastic); liquid hydrogen and deuterium targets were used. The p→+p elastic and quasielastic results are in good agreement; both the p→+p and p→+n parameters are well described by current phase shift solutions.
The elastic P P analysing power at 500 MeV incident proton energy. There is an additional overall normalization uncertainty of 1 PCT.
The spin depolarization and spin rotation parameters in 500 MeV P P elastic interactions. Additional normalization uncertainty of 1 PCT (2 PCT for DLL and DLS).
The elastic P P analysing power at 500 MeV incident proton energy. There is an additional overall normalization uncertainty of 1 PCT.
The spin correlation parameter A00NN for 497.5 MeV proton + proton elastic scattering was determined over the center-of-momentum scattering angle region 23.1°–64.9 °. The new A00NN extend to more forward angles than existing A00NN and have significantly smaller statistical errors (±0.01–0.04). The A00NN are qualitatively described by recent phase shift analyses, but a quantitative shape and normalization discrepancy remains in the forward angle region. These new data provide important constraints for nucleon-nucleon spin-dependent amplitudes at forward angles which are used in theoretical models of nucleon-nucleus scattering.
Errors include statistical and systematic uncertainties.
Measurements of π±p elastic differential cross-sections have been performed in the forward direction, using a missing-mass spark chamber spectrometer. The films have been seanned by an automatic apparatus. A phase-shift analysis of the experimental data has been done, leading to three solutions. Various experiments are proposed in order to resolve the ambiguities.
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
We have measured the inclusive prompt electron cross section over a wide momentum range (P>0.5 GeV/c) with the PEP-4 TPC detector. The semielectronic branching fractions of thec andb quarks are (9.1±0.9 (stat.)±1.3 (syst.))% and (11.0±1.8±1.0)%, respectively. Theb quark fragmentation function peaks at highz with 〈zb〉=0.74±0.05±0.03. The axial couplings to the neutral current areac=2.3±1.4±1.0 for thec quark andab=−2.0±1.9±0.5 for theb quark.
No description provided.
No description provided.
No description provided.
The inclusive production of γ's and πp0's inK−p-interactions at 32 GeV/c is studied. About 30.000 γ's coming from a Mirabelle bubble chamber experiment with a sensitivity of 6.5 ev/μb have been used for the analysis. Inclusive and topological cross sections of γ's are measured. The γ invariant differential distributions and their scaling properties are investigated. The inclusive cross section of πp0-production is determined and the πp0 invariant differential distributions are evaluated and compared to those of πp±.
No description provided.
THE CITED ERROR ON SIG( K- P --> GAMMA ANY ) TAKES INTO ACCOUNT THE UNCERTAINTIES IN THE CROSS SECTIONS CALCULATION PROCEDURE.
No description provided.
The strong interaction coupling constant α s has been measured with a new method, the planar triple energy correlation in the reaction e + e - → hadrons at center-of-mass energies ranging from 14 GeV to 46.78 GeV. A complete second-order perturbative QCD calculation was used. Λ MS = 110 ± 30 −55 +70 MeV is found.
No description provided.
No description provided.
No description provided.
With use of the MARK-J detector at s=34.7 GeV 21 000 e+e−→hadron events have been collected. By measurement of the asymmetry in angular energy correlations the strong coupling constant αs=0.13±0.01 (statistical)±0.02 (systematic) is determined, in complete second order, and independent of the fragmentation models and QCD cutoff values used.
No description provided.
Forum