ON ESTIMATING THE TOP QUARK MASS FROM GLOBAL ANALYSES OF E+E- COLLISION DATA

A study is undertaken to determine how to best extract the top quark mass m(t) within the Minimal Standard Model (MSM) using a global fit to a variety of processes (including wide-angle Bhabha scattering) in e+ e- collisions near the Z which should be measured in the coming years. Experimental cuts are accommodated as an integral part of the analysis. It is advantageous to use the collinear radiation approximation and to cut data in rapidity, center-of-mass polar angle and minimum final state invariant mass squared, s'. This avoids the need for the largest Monte Carlo acceptance correction to the data. Further, high precision cross section calculations (which include all one-loop electroweak and QED effects, certain higher-order improvements and perturbative QCD corrections as well as exponentiated soft and collinear photon radiation) then no longer require a Monte Carlo. This results in a speedup factor of at least fifty thousand ( > 5 x 10(4)) in EXPOSTAR. The data (corrected only for detector cracks, resolution and small non-collinear radiation effects) can therefore be fit quickly and directly for M(z), m(t), m(Higgs) and alpha(strong) without recourse to unphysical intermediate quantities (weak mixing angles, running couplings, partial widths, kappa*, etc.). Determination of m(t) could be as precise as +/- 15 GeV (and another +/- 20 GeV from m(Higgs) at the end of LEP running in 1991. Longitudinally polarized beams with very small polarization error could give an error on m(t) smaller by a factor almost-equal-to 4 for the same luminosity.