Philip Burrows

Abstract:

The determination of alpha_s(M_Z^2) using O(alpha_s^2) calculations of hadronic event observables in e+e- annihilation is reviewed. The large scatter among alpha_s(M_Z^2) values determined from different observables may be interpreted as arising from the effect of uncalculated higher-order contributions. The application of `optimised' perturbation theory and Pade approximants in an attempt to reduce this effect is discussed.

Abstract:

Determinations of alpha_s are reviewed. Current results are limited to a precision of around 3-20%, largely by theoretical uncertainties. All measurements are consistent with a `world average' value of 0.118 +- 0.005 and there is no evodence of any discrepancy between `low-Q^2' and `high-Q^2' results.

Abstract:

Despite many experimental verifications of the correctness of our basic understanding of QCD, there remain numerous open questions in strong interaction physics and we focus on the role of future colliders in addressing these questions. We discuss possible advances in the measurement of $\alpha_s$, in the study of parton distribution functions, and in the understanding of low $x$ physics at present colliders and potential new facilities. We also touch briefly on the role of spin physics in advancing our understanding of QCD.

Abstract:

During the past year, the SLD collaboration completed the construction and began the operation of a new vertex detector (VXD3). This detector, based on 96 CCDs of 13 cm2 area each, is an upgrade of the original vertex detector of SLD (VXD2), made possible by advances in the technology of CCD detectors. Its improved impact parameter resolution, larger solid angle coverage and virtually error-free track linking will enhance the SLD measurement of the polarization-enhanced forward-backward asymmetry for b- and c- quarks, increase the precision of the measurement of the b-fraction in hadronic Z decays, and open the possibility to observe Bs0-mixing. Full separation of primary, secondary and tertiary vertices is accessible. A description of the mechanics and electronics of VXD3 are presented along with results from the first data.