Compositeness and the asymmetries of leptons at the Z^0 peak

Abstract

We study the effects on the leptonic asymmetries A_{FB}, A_{pol} and A_{LR} coming from a model of compositeness. We consider the effects coming from the self-energies and the vertex correction to $Z{l}^{+}{l}^{-}$. Thus we use the Altarelli parametrization of the oblique corrections. We get the asymptotic limits of these corrections in terms of the parameters $(m^{\ast },\Lambda ,f,f^{\prime })$ and we get bounds for the quotient $m^{\ast }/\Lambda$ with different values of $(f,f^{\prime })$. We conclude that both asymmetries produce bounds for such quotient when $f^{\prime }$ overweigth to $f$, and this fact is related with the breakdown of the custodial symmetry.

Comments: Latex, 13 pages, 4 figures