Renormalon contributions to \delta\rho

Abstract

Leading QCD vacuum polarization contributions to the electroweak parameter $\delta \rho$ are evaluated numerically using several different prescriptions for the gluon self-energy. Simple theoretical estimates of the asymptotic behavior are given. The results show a significant contribution from the leading infrared renormalons when $\delta \rho$ is expressed in terms of the top-quark pole mass and its absence when the $\text{msbar}$ running mass is employed. The calculations are applied to estimate higher order QCD contributions to $\delta \rho$.

Comments: 9 pages, plain latex