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.
The reaction e+e−→e+e−π0π0 has been analyzed using 97 pb−1 of data taken with the Crystal Ball detector at the DESY e−e+ storage ring DORIS II at beam energies around 5.3 GeV. For the first time we have measured the cross section for γγ→π0π0 for π0π0 mvariant masses ranging from threshold to about 2 GeV. We measure an approximately flat cross section of about 10 nb for W=mπ0π0<0.8 GeV, which is below 0.6 GeV, in good agreement with a theoretical prediction based on an unitarized Born-term model. At higher invariant masses we observe formation of the f2(1270) resonance and a hint of the f0(975). We deduce the following two-photon widths: Γγγ(f2(1270))=3.19±0.16±0.280.29 keV and Γγγ(f0(975))<0.53 keV at 90% C.L. The decay-angular distributions show the π0π0 system to be dominantly spin 0 for W<0.7 GeV and spin 2, helicity 2 in the f2(1270) region, with helicity 0 contributing at most 22% (90% C.L.).
Statistical errors only.
Statistical errors only.
A proton-proton bremsstrahlung experiment has been carried out at TRIUMF using a 280-MeV polarized proton beam impinging on a liquid-hydrogen target. All three outgoing particles were detected: the higher-energy proton in a magnetic spectrometer, the lower-energy proton with plastic scintillators, and the photon in lead-glass Cherenkov detectors. The experiment shows the first unambiguous evidence for off-shell effects in the free nucleon-nucleon interaction, in that the analyzing powers disagree strongly with the predictions of the soft-photon approximation (which incorporates only on-shell information) but are consistent with the results of calculations using the Bonn and Paris potentials.
Estimated scale uncertainty is 1.5 pct.
Estimated scale uncertainty is 1.5 pct.
Estimated scale uncertainty is 1.5 pct.
We have measured the analyzing power in π+, π−, and KS0 production by a polarized proton beam at 13.3 and 18.5 GeV/c. The data cover the central and the beam fragmentation region, in the transverse-momentum range up to 2 GeV/c. The results indicate that sizable effects are present at high xF and also persist into the hard-scattering region for KS0 and π+. A zero value of the analyzing power was observed for π− production.
No description provided.
No description provided.
No description provided.
The first kinematically complete, good-statistics data for the (π,2π) reaction on the proton are presented. They involve double- and triple-differential cross sections as well as π+π− angular correlations. At energies around the Δ resonance, they exhibit a marked difference from phase space. The data are qualitatively described within the framework of an extension of Weinberg’s effective chiral Lagrangian.
No description provided.
No description provided.
We have made the first systematic precision measurement of the deuteron-deuteron total cross sections at 12 incident momenta in the range of 1.5–4.0 GeV/c on a proton synchrotron. The data were obtained by means of the transmission method covering the momentum transfer squared range of 0.001 to 0.009 (GeV/c)2 at each momentum. Our data show no anomalous structure in the excitation function and are in good agreement with Glauber model calculations including the effect of the Fermi motion of the nucleons in the deuteron except at 1.5 GeV/c, where the datum is lower than the calculated value.
Errors contain both statistics and systematics.
Energy spectra of protons, deuterons and tritons from the annihilation of antiprotons stopped in 12 C, 40 Ca, 63 Cu, 92,98 Mo and 238 U have been measured with a Ge-detector telescope. Parameters related to the shape of the spectra were calculated and their dependence on target and ejectile mass number was determined. Yields per p̄ of directly emitted protons, deuterons and tritons and of evaporated protons were estimated.
THE PROTON SPECTRA WERE FITTED WITH THE EXPRESSION N(E)=N1*EXP( -SLOPE(Q=1)*E)+N2*EXP(-SLOPE(Q=2)*E).
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
This work represents the results of an experimental investigation of the electromagnetic dissociation of 200 GeV/nucleon 16 O and 32 S ions in nuclear emulsions. Exclusive channels involving charged fragments have been studied as a function of the energy released, and, assuming a Weizsäcker-Williams spectrum of virtual photons, there is a good agreement with results for the (γ, p) processes obtained with real photons. However, the rates found for other processes are larger, in particular for the (γ, α) on both nuclei. The values of the total integrated absorption cross sections are generally larger than those obtained from real photon experiments but the extent of the discrepancy depends strongly upon which photon results are used in the comparison.
ELECTROMAGNETIC DISSOCIATION IN NUCLEAR EMULSION.
ELECTROMAGNETIC DISSOCIATION IN NUCLEAR EMULSION.
NUCLEUS IS THE EMULSION.
An analysis has been performed of neutrino and antineutrino interactions with protons and neutrons in a deuterium bubble chamber. The interactions under study are quasielastic neutrino-neutron scattering and one-, two- and three-pion production reactions. Results are presented on cross sections, effective mass distributions, resonance production, momentum transfer distributions and coefficients of the decay angular distributions. Where possible, comparisons are made with existing theoretical models and predictions.
No description provided.
Numerical values supplied by A.Tenner.
Numerical values supplied by A.Tenner.
The inclusive production of neutral kaons is studied inK+p and π+p interactions at 250 GeV/c. Total and semi-inclusive cross sections and average kaon multiplicities are presented and compared with the data at lower energies. The longitudinal and transverse momentum distributions and their energy dependence are analyzed. The results are interpreted in the framework of recent parton models.
No description provided.
No description provided.
No description provided.
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