Quark mass effects toO(α _s ) ine ⁺ e ⁻→hadrons asymmetries and precision tests of electroweak physics

Abstract

We estimate, to first order in α _s , quark mass effects on a number of fully integrated and “two-jet” asymmetries for the processe ⁺ e ⁻→$q\bar q \to q\bar qg$. We find that the effects of strong interactions are appreciably decreased, especially in the case of theb quark, with respect to the massless case. For the fully integrated asymmetries these effects are sizeable. Concentrating on the “two-jet” asymmetries, we find that for small values of the parameters ε and δ defining a ”two-jet” event all the asymmetries are α _s independent. For larger values of these parameters this is no longer true. However it is still possible to define regions in the (ε, δ) plane where the strong interaction effects can be made arbitrarily small. These important features enhance the role of “two-jet” asymmetries as specially convenient candidates for high precision tests of Electroweak Physics.