Results on the production cross sections ofW andZ bosons detected in the UA2 experiment are given based on a large sample ofW→eν andZ→e+e− decays. The measured cross sections are σWe = 660±15(stat)±37(syst)pb, σZe = 70.4±5.5(stat)±4.0(syst)pb and their ratioR=9.38−0.72+0.82(stat)±0.25(syst). In the framework of the Standard Model, the measured value ofR is used to determine the total width of theW, Γ(W)=2.30±0.19(stat)±0.06(syst) GeV.
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The ratio R of the total cross section for e+e− annihilation into hadrons to the lowest-order QED cross section for e+e−→μ+μ− has been measured for center-of-mass energies ranging from 50 to 61.4 GeV. If we allow for an overall shift of —4.9%, about 1.5 times our estimated normalization error, the results are consistent with the standard-model predictions.
Error quoted contains point-to-point systematics. There is also an additional 3.2 pct systematic error.
The angular distributions of the reactione+e−→μ+μ− ande+e+→τ+τ− have been measured between\(\sqrt s= 50\) and 60.8 GeV with the VENUS detector at TRISTAN. The average total cross section and the forward-backward charge asymmetry for μ-pair production are observed to be 28.3±1.4±0.8 pb and (−29.0−4.8+5.0±0.5)%, and those for τ-pair production are 27.6±1.7±1.0 pb and (−32.8−6.2+6.4±1.5)% at\(\langle \sqrt s \rangle \). These values are consistent with the predictions of the standard model of electroweak interactions.
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Jet properties ine+e− annihilation at center of mass energies of 14, 22, 35 and 43.7 GeV were studied with the data collected in the TASSO detector at PETRA, using the same evaluation procedures for all the energies. The total hadronic cross section ratio for the center of mass energy interval 39–47 GeV was determined to be ℛ=4.11±0.05 (stat)±0.18(syst.) at\(\langle \sqrt s \rangle= 43 - 7\) GeV. Corrected distributions of global shape variables are presented as well as the inclusive charged particle distributions for scaled momentum and transverse momentum. The center of mass energy evolution of the average sphericity, thrust, aplanarity and particle momentum is shown.
R values. First systematic error comes from selection cuts and Monte Carlo, the second from the luminosity measurement and missing terms in the radiative correction calculations.
Normalised scaled momentum distributions. Data have combined statistical and systematic errors. These data superceded previous TASSO data (ZP C22 (84) 307 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1279> RED = 1279 </a>)).
Normalised scaled momentum distributions. Data have combined statistical and systematic errors. The binning is as used in fits in the paper. These data superceded previous TASSO data (ZP C22 (84) 307 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1279> RED = 1279 </a>)).
Hadronic decays of Z 0 bosons are studied in the Delphi detector. Global event variables and singel particles inclusive distributions are compared with QCD-based predictions. The mean charged multiplicity is found to be 20.6±1.0 (stat+syst). The mean values of the sphericity, aplanarity, thrust, minor value, p in T and p out T are compared with values found at lower energy e + e − colliders.
Corrected Sphericity distribution. Statistical errors only.
Corrected Aplanarity distribution. Statistical errors only.
Corrected Q3-Q2 distribution. Statistical errors only.
Using data onvp and\(\bar vp\) charged current interactions from a bubble chamber experiment with BEBC at CERN, the average multiplicities of charged hadrons and pions are determined as functions ofW2 andQ2. The analysis is based on ∼20000 events with incidentv and ∼10000 events with incident\(\bar v\). In addition to the known dependence of the average multiplicity onW2 a weak dependence onQ2 for fixed intervals ofW is observed. ForW>2 GeV andQ2>0.1 GeV2 the average multiplicity of charged hadrons is well described by〈n〉=a1+a2ln(W2/GeV2)+a3ln(Q2/GeV2) witha1=0.465±0.053,a2=1.211±0.021,a3=0.103±0.014 for thevp anda1=−0.372±0.073,a2=1.245±0.028,a3=0.093±0.015 for the\(\bar vp\) reaction.
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The study of the J ψ transverse momentum distribution in oxygen-uranium reactions at 200 GeV/nucleon shows that 〈 P T 〉 and 〈 P T 2 〉 increase with the transverse energy of the reaction. Muon pairs in the mass continuum do not exhibit the same behaviour. The comparison of the J ψ production rates in central and peripheral collisions shows a significant diminution for low P T central events.
Two parametrization of the D(SIG)/D(PT) are used: first is : PT*exp(-SLOPE*PT**CONST(C=PT)) and second is : PT*exp(-2*MT/CONST(C=MT)).
D(SIG)/D(PT) is parameterized as PT*exp(-SLOPE*PT**CONST).
D(SIG)/D(PT) is parameterized as PT*exp(-SLOPE*PT**CONST).
A search for the 0 + → 2 + neutrinoless double-beta decay of 76 Ge into the first excited state of 76 Se has been carried out using a coincidence technique between Ge and NaI detectors. Since the expected number of counts is very small and mixed with a continuous background of natural radioactivity, special care has been taken to maintain the good energy resolution of the detectors. As a consequence, the experimental data display, after 6207 h statistical time, a coincidence signal of 19.3 ± 5.8 counts, between an energy deposition of 1484.0 ± 0.3 keV in the Ge detectors and 561 ± 10 keV in the NaI detectors. Both Ge and NaI energies are within the experimental errors, compatible with the expected values. No other unidentified coincidence signal has been found in the full Ge-NaI energy matrix, and no similar γγ cascade has been found within our background. Even if the low statistics does not completely rule out the possibility of a statistical fluctuation, this result should encourage further experiments with improved sensitivities.
SE76* IS IN 2+ EXGITED STATE.
In an experiment using the CERN SPS hyperon beam, we have measured the cross sections for inclusive production of Ξ0 (accompanied by a charged particle), Ξ(1530)- and Ξ(1530)0 in Ξ--beryllium collisions at 116 GeV/c. All differential cross sections are found to be well described by the from (1−xF)n exp (−bpT2) over the whole accessible kinematical region (xF>0.3). The invariant production spectra for Ξ0, Ξ(1530)- and Ξ(1530)0, as well as those for Ξ-, and Ω- (obtained previously from the same data), are compared to theoretical predictions deduced from a two-component quark-diquark cascade model.
Total Inelastic Cross Section. This is an estimate based on the measurements of N BE --> INELASTIC and N P --> INELASTIC (T J Roberts et al., NP B159 (1979), 56) and the measurement of XI- P --> INELASTIC (S F Biagi et al., NP B186 (1981), 1).
The XI- and OMEGA- data were computed from Biagi et al., ZP C34 (87) 187.
We report on a study of ρ0, ρ+, ω,\(\bar K^{*0} (892)\) andK*0 (892) inclusive production in π+p interactions at 250 GeV/c, for ρ+,\(\bar K^{*0} (892)\) for the first time in a π+p experiment. The data are compared withK+p data in the same experiment, with results of other experiments and with quark-parton models. Interesting differences are found between ρ+,0 and ω production.
Inclusive cross sections and average multiplicity per inelastic collision.
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