New results on $\alpha_{S}(M^{2}_{Z})$ and $\alpha(M^{2}_{Z})$

The experimental situation on αs (M2Z) is reviewed. A good agreement between the different approaches L• observed with a combined value αs (M2Z) = 0.1192±0.0020. Particular emphasis is given to the very recent determination from hadronic T decays by ALEPH, yielding the most precise value to date: the low energy scale involved requires some care, but the approach is validated by tests on the data exploiting the information contained in the measured vector and axial-vector spectral functions. It turns out that these results have motivated a new approach to the calculations of hadronic vacuum polarisation, providing a significant improvement in their precision. The value found for the QED coupling at the Z scale α−1(M2z) = 128.933 ± 0.015exp ± 0.015,, allows the derivation of more stringent bounds on the Higgs mass MH=(83+61−38) GeV/c2 through the global electroweak fit. The new determination of the hadronic contribution to the muon magnetic anomaly ahadμ = (692.4 ± 5.6.,p ± 2.6,,) x 10−10 has a precision such that it does not prevent anymore the experimental investigation of the weak contribution to aµ.