Strong coupling, unification, and recent data

The prediction of strong coupling assuming (supersymmetric) coupling constant unification is reexamined. We find, using the new electroweak data, ${\mathrm{\alpha }}_{\mathit{s}}$(${\mathit{M}}_{\mathit{Z}}$)≊0.129±0.010. The implications of the large ${\mathrm{\alpha }}_{\mathit{s}}$ value are discussed. The role played by the Z quark width is stressed. It is also emphasized that high-energy (but not low-energy) corrections could significantly diminish the prediction. However, unless higher-dimension operators are assumed to be suppressed, at present one cannot place strong constraints on the superheavy spectrum. Nonleading electroweak threshold corrections are also discussed.