The strong coupling alpha_s(M_Z^2) has been measured using hadronic decays of Z^0 bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O(alpha_s^2), and including resummed analytic formulae based on the next-to-leading logarithm approximation. In this comprehensive analysis we studied event shapes, jet rates, particle correlations, and angular energy flow, and checked the consistency between alpha_s(M_Z^2) values extracted from these different measures. Combining all results we obtain alpha_s(M_Z^2) = 0.1200 \pm 0.0025(exp.) \pm 0.0078(theor.), where the dominant uncertainty is from uncalculated higher order contributions.
JCEF is the jet cone energy fraction.
We present a precise measurement of the left-right cross section asymmetry ($A_{LR}$) for $Z$ boson production by $\ee$ collisions. The measurement was performed at a center-of-mass energy of 91.26 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (63.0$\pm$1.1)%. Using a sample of 49,392 $\z0$ decays, we measure $A_{LR}$ to be 0.1628$\pm$0.0071(stat.)$\pm$0.0028(syst.) which determines the effective weak mixing angle to be $\swein=0.2292\pm0.0009({\rm stat.})\pm0.0004({\rm syst.})$.}
The left-right asymmetry and effective weak mixing angle corrected to the pole energy value, taking into account photon exchange and electro weak interferences. L and R refer to left and right beam polarizations.
We present a new measurement of the left-right cross section asymmetry (ALR) 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, ALR0, to be 0.1512+-0.0042(stat.)+-0.0011(syst.) which is equivalent to an effective weak mixing angle of sin**2(theta_eff)=0.23100+-0.00054(stat.)+-0.00014(syst.).
The left-right asymmetry and effective weak mixing angle corrected to the pole energy value, taking into account photon exclusive and electroweak interference effects of total-state radiation.
We have measured the differential production cross sections as a function of scaled momentum x_p=2p/E_cm of the identified hadron species pi+, K+, K0, K*0, phi, p, Lambda0, and of the corresponding antihadron species in inclusive hadronic Z0 decays, as well as separately for Z0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the Modified Leading Logarithm Approximation with the ansatz of Local Parton-Hadron Duality, and the predictions of three fragmentation models. Ratios of production of different hadron species were also measured as a function of x_p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x_p in light quark (as opposed to antiquark) jets. Differences are observed at high x_p, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x_p fragmentation products.
Measured differential cross section for phi meson production per Z0 decay into light, charm and bottom quarks separately. The errors given are the sum in quadrature of the statistical errors and those systematic errors arising from theunfolding procedure. Systematic errors common to the three flavours are not inc luded.
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