DETERMINING ALPHA(S) FROM MEASUREMENTS AT ZETA - HOW NATURE PROMPTS US ABOUT NEW PHYSICS

The value of alpha 3(Mz) emerging from the so-called global fits based mainly on the data at the Z peak (and assuming the standard model) is three standard deviations higher than the one stemming from the low-energy phenomenology. The corresponding value of boolean AND(QCD) is very large, similar to 500 MeV, and is incompatible with crucial features of QCD. If persists, the discrepancy should be interpreted as due to contributions to the Z-quark-antiquark vertices which go beyond the standard model.