With use of three-prong τ decays observed by the Mark II detector at the Stanford Linear Accelerator Center (PEP), the τ lifetime is measured to be (4.6±1.9)×10-13 sec. © 1982 The American Physical Society.

Energy correlations have been measured with the MARK II detector at the PEP storage ring (Stanford Linear Accelerator Center) at c.m. energy of 29 GeV and are compared to first-order QCD predictions. Fragmentation processes are significant and limit the precision with which the first-order strong-coupling constant can be determined. © 1982 The American Physical Society.

The charged-particle multiplicity distribution in decays is determined from data collected at the e+e- storage ring PEP. The one-, three-, and five-charged-particle inclusive branching fractions are (86 ± 2)%, (14 ± 2)%, and < 0.5%, respectively. © 1982 The American Physical Society.

A search for charged, pointlike, spin-0 particles with large couplings to the τ lepton has been done at the PEP e+e- storage ring (Stanford Linear Accelerator Center). No evidence for such particles is seen, and limits are placed on the branching fraction to τντ as a function of mass. © 1982 The American Physical Society.

The production of the charmed meson state D*+ has been observed in e+e- annihilation at 29 GeV. The fragmentation function for charmed quarks appears to be peaked about z=0.5. © 1982 The American Physical Society.

Measurements are presented of the inclusive charged-particle cross sections s dσdx for e+e- annihilation at center-of-mass energies of 5.2, 6.5, and 29.0 GeV. Significant scale breaking is observed in these cross sections. © 1982 The American Physical Society.

We report a measurement of the branching fraction for ψ(3770)→γχc1 and search for the transition ψ(3770)→γχc2 based on 2.92 fb-1 of e+e- data accumulated at s=3.773 GeV with the BESIII detector at the BEPCII collider. We measure B(ψ(3770)→γχc1)=(2.48±0.15±0.23)×10-3, which is the most precise measurement to date. The upper limit on the branching fraction of ψ(3770)→γχc2 at a 90% confidence level is B(ψ(3770)→γχc2)<0.64×10-3. The corresponding partial widths are Γ(ψ(3770)→γχc1)=(67.5±4.1±6.7) keV and Γ(ψ(3770)→γχc2)<17.4 keV.

The process e+e−→ pp̄π0has been studied by analyzing data collected at (formula presented) GeV, at (formula presented) GeV, and during a ψ(3770) line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of p̄pπ0in the vicinity of the ψ(3770) is measured, and the Born cross section of ψ(3770) → p̄pπ0is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5 σ are found. The solutions for the Born cross section of ψ(3770) → p̄pπ0are 33.8 ± 1.8 ± 2.1 pb and (formula presented) pb (< 0.22 pb at a 90% confidence level). Using the estimated cross section and a constant decay amplitude approximation, the cross section σ(p̄p → ψ(3770)π0) is calculated for the kinematic situation of the planned P̄ANDA experiment. The maximum cross section corresponding to the two solutions is expected to be less than 0.79 nb at 90% confidence level and 122 ± 10 nb at a center-of-mass energy of 5.26 GeV.