Information and discrimination frombquark production on theZresonance

We introduce and define operatively, in a model-independent way, a new ‘‘heavy’’ b-vertex parameter ${\mathrm{\eta }}_{\mathit{b}}$ that can be derived from the measurement of a special polarization asymmetry for production of b quarks on the Z resonance. We show that the combination of the measurement of ${\mathrm{\eta }}_{\mathit{b}}$ with that of a second and previously defined ‘‘heavy’’ b-vertex parameter ${\mathrm{\delta }}_{\mathit{b}\mathit{V}}$ can discriminate a number of models of new physics that are associated with different ‘‘trajectories’’ in the plane of the variations of the two parameters. This is shown in particular for some popular SUSY and technicolor-type models. In general, this discrimination is possible if a measurement of both parameters is performed.