A search for pair production of stable charged particles from Z decay has been performed with the Mark II detector at the SLAC Linear Collider. Particle masses are determined from momentum, ionization energy loss, and time-of-flight measurements. A limit excluding pair production of stable fourth-generation charged leptons and stable mirror fermions with masses between the muon mass and 36.3 GeV/c2 is set at the 95% confidence level. Pair production of stable supersymmetric scalar leptons with masses between the muon mass and 32.6 GeV/c2 is also excluded. © 1990 The American Physical Society.

We have measured the mass of the Z boson to be 91.110.23 GeV/c2, and its width to be 1.61-0.43+0.60 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.620.23 GeV, corresponding to 3.81.4 neutrino species. © 1989 The American Physical Society.

We have searched for supersymmetric particles in 528 Z decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower mass limits on degenerate squarks, nondegenerate up-type squarks, nondegenerate down-type squarks, charginos, pair-produced unstable neutralinos, and neutralinos from associated production. © 1990 The American Physical Society.

Using isolated leptons reconstructed in the Mark II detector to tag bb events, we measure the fraction of bb events in hadronic Z0 decays to be 0.23-0.09+0.11, in good agreement with the standard-model prediction of 0.22. We find (Zbb)=0.43-0.17+0.21 GeV. © 1990 The American Physical Society.

A precise measurement of the ratio R of the total cross section e+e-hadrons to the pointlike cross section e+e-+- at a center-of-mass energy of 29.0 GeV is presented. The data were taken with the upgraded Mark II detector at the SLAC storage ring PEP. The result is R=3.920.050.09. The luminosity has been determined with three independent luminosity monitors measuring Bhabha scattering at different angular intervals. Recent calculations of higher-order QED radiative corrections are used to estimate the systematic error due to missing higher-order radiative corrections in the Monte Carlo event generators. © 1991 The American Physical Society.

We have observed hadronic final states produced in the decays of Z bosons. In order to study the parton structure of these events, we compare the distributions in sphericity, thurst, aplanarity, and number of jets to the predictions of several QCD-based models and to data from lower energies. The data and models agree within the present statistical precision. © 1989 The American Physical Society.

We have measured the mass of the Z boson to be 91.14±0.12 GeV/c2, and its width to be 2.42-0.35+0.45 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.46±0.10 GeV, corresponding to 2.8±0.6 neutrino species, with a 95%-confidence-level upper limit of 3.9. © 1989 The American Physical Society.

We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were charged-particle multiplicity, scaled momentum, and momenta transverse to the sphericity axes. The distributions have been corrected for detector effects and are compared with data from ee- annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations. © 1990 The American Physical Society.