The full TASSO data have been used to study the orientation of three-jet events ine+e− annihilation. The polar angle distributions of the normal to the three-jet plane as well as the polar angle distribution of the most energetic jet have been measured as a function of the thrust cut-off used to select the three-jet sample. The data corrected for radiation and detector effects are compared to QCD predictions and fair agreement is found. As a consistency check we also present measurements of the azimuthal correlations between the lepton and hadron planes. A significant azimuthal dependence is found, consistent again with the QCD predictions.
No description provided.
Results are presented on an investigation of photons produced in multihadronic final states frome+e− annihilation at 35 GeV and 44 GeV center of mass energies. Scalling violation between 14 and 44 GeV is observed in inclusive photon spectra. Comparing inclusive π0 spectra with charged pion spectra it is found that the average π0 multiplicity exceeds the charged pion multiplicity scaled by factor of 0.5 by (16±5)% and (21±7)% at 35 and 44 GeV respectively. The excess can be attributed to isospin violating decays of hadrons. The η multiplicity is found to be 〈nη〈=0.64±0.09±0.06 at 35 GeV. With a significance of three standard deviations a signal from quark bremsstrahlung is observed. The measured charge asymmetry in hadronic final states, due to the interference between initial and final state radiation, ofA=−0.141±0.041 is in accord with QED expectations. An interference effect in the azimuth angle distribution of charged jets around the photon direction is observed for the first time.
No description provided.
No description provided.
No description provided.
The Fermilab 15-ft bubble chamber has been exposed to a quadrupole triplet neutrino beam produced at the Tevatron. The ratio of ν to ν¯ in the beam is approximately 2.5. The mean event energy for ν-induced charged-current events is 150 GeV, and for ν¯-induced charged-current events it is 110 GeV. A total of 64 dimuon candidates (1 μ+μ+, 52 μ−μ+ and μ+μ−, and 11 μ−μ−) is observed in the data sample of approximately 13 300 charged-current events. The number and properties of the μ−μ− and μ+μ+ candidates are consistent with their being produced by background processes, the important sources being π and K decay and punchthrough. The 90%-C.L. upper limit for μ−μ−/μ− for muon momenta above 4 GeV/c is 1.2×10−3, and for momenta above 9 GeV/c this limit is 1.1×10−3. The opposite-sign-dimuon–to–single-muon ratio is (0.62±0.13)% for muon momenta above 4 GeV/c. There are eight neutral strange particles in the opposite-sign sample, leading to a rate per dimuon event of 0.65±0.29. The opposite-sign-dimuon sample is consistent with the hypothesis of charm production and decay.
No description provided.
No description provided.
No description provided.
We present a measurement of the total cross section for γγ→hadrons, with one photon quasireal and the other a spacelike photon of mass squared −Q2. Results are presented as a function of Q2 and the γγ center-of-mass energy W, with the Q2 range extending from 0.2 to 60 GeV2, and W in the range from 2 to 10 GeV. The data were taken with the TPC/Two-Gamma facility at the SLAC e+e− storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle falloff with increasing W. Its Q2 dependence is shown to be well described by an incoherent sum of vector-meson and pointlike scattering over most of the observed W range. Agreement at high Q2 is improved if a minimum-pT cutoff (motivated by QCD) is imposed on the pointlike contribution.
Errors are statistical only.
Errors are statistical only.
Errors are statistical only.
None
Interacting beam cross-section.
No description provided.
No description provided.
The two-jet differential cross section d3σ(p¯p→jet 1+jet 2+X)/dEtdη1dη2, averaged over -0.6≤η1≤0.6, at √s =1.8 TeV, has been measured in the Collider Detector at Fermilab. The predictions of leading-order quantum chromodynamics for most choices of structure functions show agreement with the data.
Systematic error contains all known systematic uncertainties, including the effect of uncertainties in the energy scale.
Systematic error contains all known systematic uncertainties, including the effect of uncertainties in the energy scale.
Systematic error contains all known systematic uncertainties, including the effect of uncertainties in the energy scale.
The analyzing power (spin-dependent azimuthal asymmetry) has been observed for the first time in the nuclear Coulomb coherent production process, the ‘‘Primakoff process,’’ with the use of the newly constructed 185-GeV/c Fermilab polarized proton beam. We have observed a large asymmetry of this process in the regions of ‖t’‖<0.001 (GeV/c)2 and 1.36<M(π0p)<1.52 GeV/c2, where the Coulomb process is predominant. The measured asymmetry is consistent with the analyzing power of the existing low-energy γ+p→π0+p data.
No description provided.
No description provided.
We have measured the deuteron A ( Q 2 ) structure function in the momentum transfer region between 1 and 18 fm −2 . The accuracy of the data ranges from 2 to 6%. These measurements allow a sensitive test of theoretical predictions. We find that meson-exchange currents and relativistic corrections significantly improve the agreement between experiment and theory. We investigate the sensitivity of A ( Q 2 ) to the nucleon-nucleon interaction and to the neutron electric form factor G E n ( Q 2 ). Our analysis shows that G E n ( Q 2 ) can be extracted from these data with a significantly improved accuracy. The model dependence of this analysis is discussed.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Small angle scattering of 280 GeV positive muons by deuterium, carbon and calcium has been measured at scattering angles down to 2 mrad. The nucleon structure function F 2 extracted from deuterium does not show a significant x dependence in the measured range of Q 2 and its Q 2 dependence is linear in log Q 2 . For calcium, a depletion of F 2 is observed at low x by 30% as compared with the values at x = 0.1 where F 2 (Ca) and F 2 (D) are not significantly different. This depletion is attributed to shadowing. The carbon structure function exhibits a similar, but less pronounced, x dependence. Such behaviour is observed to be independent of Q 2 . The data are consistent with those obtained from other charged lepton experiments both at similar and higher values of x and Q 2 and considerably extend the range of the measurements down to the low values of x to be measured in forthcoming experiments at HERA.
Deuterium data. Overall normalization error of 7 pct not included.
Deuterium data. Overall normalization error of 7 pct not included.
Deuterium data. Overall normalization error of 7 pct not included.
Using the ARGUS detector at the DORIS II e + e − storage ring at DESY, we have obtained evidence for a new charmed-strange meson which decays into D *+ K 0 . Its mass is observed to be 2535.9±0.6±2.0 MeV/ c 2 and its width to be less than 4.6 MeV/ c 2 at the 90% confidence level. No structure is observed at this mass in the D + K 0 invariant mass spectrum, which suggests that an unnatural spin-parity is preferred.
No description provided.
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