On estimating the top quark mass from global analyses ofe+e− collision data

A study is undertaken to determine how to best extract the top quark massm t within the Minimal Standard Model (MSM) using a global fit to a variety of processes (including wide-angle Bhabha scattering) ine+e− collisions near theZ 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 (>5×104) in EXPOSTAR. The data (corrected only for detector cracks, resolution and small non-collinear radiation effects) can therefore be fit quickly and directly forM z ,m t ,mHiggs and αstrong without recourse to unphysical intermediate quantities (weak mixing angles, running couplings, partial widths, κ*, etc.) Determination ofm t could be as precise as ±15 GeV (and another±20 GeV frommHiggs) at the end of LEP running in 1991. Longitudinally polarized beams with very small polarization error could give an error onm t smaller, by a factor ≈4 for the same luminosity.