Measurement of the Branching Fraction for τ→ρν

This Letter presents a measurement of the decay τ-→ρ-ντ using data obtained with the Mark II detector at SPEAR. In the center-of-mass energy region 4.5<~Ec.m.<~6.0 GeV 85 events are observed in which a charged ρ was found in coincidence with either an electron or a muon. It was determined that B(τ-→ρ-ντ)=(20.5±4.1)% and the ratio B(τ-→ρ-ντ)B(τ-→e-ντν̄e)=1.11± 0.23. © 1979 The American Physical Society

Limits on J ψ and ϒproduction in e + e - interactions at s = 29 GeV

A search has been made for the inclusive production of J ψ (3.1) and Υ{hooked} (9.4) mesons in e+e- interactions at 29 GeV, via their decay into two leptons. No signal is observed in the J ψ region, nor in the Υ{hooked} region. The limits on the cross sections are σ(e+e- → ψX) < 4.4 × 10-36cm2, and σ(e+e- → Υ{hooked}X) < 4.7 × 10-36 cm2. The same data yield limits on the branching ratios for the b quark BR (b → ψX) < 4.9% and BR (b → ℓ+ℓ-X) < 0.8%. © 1983

Limits on J ψ and ϒproduction in e + e - interactions at s = 29 GeV

A search has been made for the inclusive production of J ψ (3.1) and Υ{hooked} (9.4) mesons in e+e- interactions at 29 GeV, via their decay into two leptons. No signal is observed in the J ψ region, nor in the Υ{hooked} region. The limits on the cross sections are σ(e+e- → ψX) < 4.4 × 10-36cm2, and σ(e+e- → Υ{hooked}X) < 4.7 × 10-36 cm2. The same data yield limits on the branching ratios for the b quark BR (b → ψX) < 4.9% and BR (b → ℓ+ℓ-X) < 0.8%. © 1983

Inclusive electron production in e+e- annihilation at 29 GeV

The total momentum and transverse momentum spectra of electrons in e+e- annihilation at 29 GeV have been measured. The inclusive cross section is determined to be 14.4±1.6±5.2 pb for momenta greater than 2 GeV/c. The average semielectronic branching ratios of charm and bottom quarks are measured to be (6.3±1.2±2.1)% and (11.6±2.1±1.7)%, respectively. The fragmentation function for bottom quarks is determined to be peaked at high z, with zb=0.75±0.05±0.04. © 1983 The American Physical Society

A study of the decay τ-→π-μτ

We present a high statistics measurement of the branching ratio for the decay τ-→π-μτ using data obtained with the Mark II detector at the SLAC e+e- storage ring SPEAR. We have used events from the center-of-mass energy region 3.52 to 6.7 GeV to determine that B(τ-→π-μτ)=0.117±0.004±0.018. From electron-muon events in the same data sample, we have determined that B(τ-→π-μτ) B(τ-→e--μeμτ)=0.66±0.03±0.11. We present measurements of the mass and spin of the τ and the mass of the τ neutrino based, for the first time, on a hadronic decay mode of the τ. © 1982

Measurement of High-Energy Direct Photons in Decays

The inclusive and 0 momentum distributions at the have been measured. Using these data and estimates of production, it is found that (4.1 0.8)% of decays contain a direct photon with energy greater than 60% of the beam energy. The expected momentum distribution for direct photons calculated to lowest order in quantum chromodynamics is qualitatively different from that observed in the data. © 1980 The American Physical Society