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We present measurements of Rs using the SLD at the SLC. The analyses use 2D and 3D impact parameter tags and a displaced 3D vertex tag which all exploit the small size and stability of the e+e-interaction point and the precision 3D CCD pixel vertex detector to achieve high b&tagging efficiencies and purities. The combined measurement yields Rb = 0.229 f 0.011 and is consistent with standard model predictions.PACS number(s): 13.38.Dg, 13.65.+i

We present a new measurement of the left-right cross section asymmetry (A LR ) for Z boson production by e + e − collisions. The measurement was performed at a center-of-mass energy of 91.28 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (77.23±0.52)%. Using a sample of 93,644 Z decays, we measure the pole-value of the asymmetry, A 0 LR , to be 0.1512±0.0042(stat.)±0.0011(syst.) which is equivalent to an effective weak mixing angle of sin 2 θ eff W = 0.23100 ± 0.00054(stat.) ± 0.00014(syst.). Submitted to Physical Review LettersM. Carpinelli,A. Chou,S. Fahey,T. Gillman,J.L. Harton, T.W. Markiewicz,A.K. McKemey, (4) B.T. Meadows,T.B. Moore,M. Nussbaum,J. Quigley,O.H. Saxton,S. Sen,D.J. Sherden,M.B. Smy,T. Takahashi,T. Usher,A.W. Weidemann, R.W. Zdarko, (28) and J. Zhou,(1) Adelphi University, Garden City, New York 11530 The left-right asymmetry is defined as, where σ L and σ R are the e + e − production cross sections for Z bosons at the Z-pole energy with left-handed and right-handed electrons, respectively. The Standard Model predicts that this quantity depends upon the effective vector (v e ) and axial-vector (a e ) couplings of the Z boson to the electron current,where the effective electroweak mixing parameter is defined 5The operation of the SLC with a polarized electron beam has been described previously [5]. In 1994, the beam polarization at the SLC source [6] was increased from 63% to ∼ 80% by the use of a thinner (0.1 µm) strained-lattice GaAs photocathode [7] which was illuminated by a pulsed Ti:Sapphire laser operating at 845 nm. The circular polarization state of each laser pulse (and hence, the helicity of each electron pulse) was chosen randomly. The electron spin orientation was manipulated in the SLC North Arc by a pair of large amplitude betatron oscillations to achieve longitudinal polarization at the SLC interaction point (IP) The counting rates in each detector channel are measured for three combinations of electron and photon beam parameters: parallel electron and photon helicities, antiparallel helicities, and photon beam absent. The latter combination is used to measure detector background. The asymmetry formed from the background-subtracted counting rates is

We have measured the distributions of the jet energies in e ϩ e Ϫ →qqg events, and of the three orientation angles of the event plane, using hadronic Z 0 decays collected in the SLD experiment at SLAC. We find that the data are well described by perturbative QCD incorporating vector gluons. We have also studied models of scalar and tensor gluon production and find them to be incompatible with our data. ͓S0556-2821͑97͒00105-7͔