Measurement of the F-meson lifetime.

The lifetime of the F meson has been measured to be (3.5-1.8+2.40.9) × 10-13 s by means of the F decay mode. The measurement was made with the High Resolution Spectrometer at the SLAC e+e- storage ring PEP at a center-of-mass energy of 29 GeV. © 1986 The American Physical Society

Upper limit on the tau-neutrino mass.

A sample of lepton decays to 5± and 5±0 observed in the high-resolution spectrometer at the SLACe+e- storage ring PEP, has been used to place an upper limit on the mass of the tau neutrino of 84 MeV/c2 at the 95% confidence level. © 1986 The American Physical Society

Experimental study of the reactions e+e--->e+e- and e+e---> gamma gamma at 29 GeV.

This paper reports measurements of the differential cross sections for the reactions e+e-'e+e- (Bhabha scattering) and e+e-' (-pair production). The reactions are studied at a center-of-mass energy of 29 GeV and in the polar-angular region -costheta -<0.55. A direct cross-section comparison between these two reactions provides a sensitive test of the predictions of quantum electrodynamics (QED) to order ±3. When the ratio of -pair to Bhabha experimental cross sections, integrated over -costheta -<0.55, is divided by the same ratio predicted from ±3 QED theory, the result is 1.007±0.009±0.008. The 95%-confidence limits on the QED-cutoff parameters are +>154 GeV and ->220 GeV for Bhabha scattering, and +>59 GeV and ->59 GeV for -pair production. © 1986 The American Physical Society

Lambda production in e+e- annihilations at 29 GeV: Comparison with Lund-model predictions.

This paper presents measurements of the inclusive production cross sections of baryons in e+e- annihilations at s=29 GeV. The data sample corresponds to an integrated luminosity of 256 pb-1 collected with the High-Resolution Spectrometer at the SLAC storage ring PEP. Comparisons are made to the predictions of the Lund model. The data are well described with use of a strange-diquark suppression parameter, (usud)(sd), of 0.89 0.10-0.16+0.56, and the measured c+X branching ratio of (23 10)%. © 1986 The American Physical Society

Experimental study of the reactions e+e--->e+e- and e+e---> gamma gamma at 29 GeV.

This paper reports measurements of the differential cross sections for the reactions e+e-'e+e- (Bhabha scattering) and e+e-' (-pair production). The reactions are studied at a center-of-mass energy of 29 GeV and in the polar-angular region -costheta -154 GeV and ->220 GeV for Bhabha scattering, and +>59 GeV and ->59 GeV for -pair production. © 1986 The American Physical Society

Neutral K*(890) and ρ0 meson production in e+e- annihilation at ;s=29GeV

The production of neutral K*(890) and ρ0 mesons was studied in e+e- annihilation at s=29 GeV using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to π0 and K0 production. The measured multiplicities are 0.84±0.08 ρ{variant}0 mesons and 0.57±0.09 K*0(890) mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model. © 1985

Study of quark fragmentation in e+e- annihilation at 29 GeV: Charged-particle multiplicity and single-particle rapidity distributions.

This paper presents the charged-particle multiplicity distributions for e+e- annihilation at s =29 GeV measured in the High Resolution Spectrometer. The data, which correspond to an integrated luminosity of 185 pb-1, were obtained at the SLAC e+e- storage ring PEP. The techniques used to correct the observed prong numbers are discussed. The multiplicity distribution of the charged particles has a mean value n=12.87±0.03±0.30, a dispersion D2=3.67±0.02±0.18, and an f2 moment of 0.60±0.02±0. 18. Results are also presented for a two-jet sample selected with low sphericity and aplanarity. The charged-particle distributions are almost Poissonian and narrower than have been reported by other e+e- experiments in this energy range. The mean multiplicity increases with the event sphericity, and for the sample of threefold-symmetric three-jet events, a value of n=16.3±0.3±0.7 is found. No correlation is observed between the multiplicities in the two hemispheres when the events are divided into two jets by a plane perpendicular to the thrust axis. This result is in contrast with the situation in soft hadronic collisions, where a strong forward-backward correlation is measured. For the single jets, a mean multiplicity of 6.43±0.02±0.15 and a dispersion value of D2=2.55±0.02±0.13 are found. These values give further support to the idea of independent jet fragmentation. The multiplicity distributions are well fit by the negative-binomial distribution. The semi-inclusive rapidity distributions are presented. Comparisons are made to the measurements of charged-particle multiplicities in hadron-hadron and lepton-nucleon collisions. © 1986 The American Physical Society

Production of phi and F(1970)--> phi pi in e+e- annihilation at 29 GeV.

Data from the high-resolution spectrometer at PEP have been used to study the inclusive production of mesons and F mesons decaying into . Fragmentation functions and cross sections are presented and compared to existing data. The total cross section at 29 GeV is 406 pb. The observed F signal in the region z>0.4, given the assumption that R(F)[R(F)+R(D)]=0.15, corresponds to an F branching ratio of (3.31.1)%. The measured F mass is 196333 MeV/c2. © 1985 The American Physical Society