arXiv subjects
Publications and source records attributed to Paolo Gambino.
The radiative corrections involved in the precise determination of the electroweak mixing angle measured at the Z-peak are reviewed in detail, with particular emphasis on the new calculation of two-loop heavy top effects. This example serves as a brief pedagogical introduction to the problems and techniques of higher order electroweak calculations.
The corrections induced by a heavy top on the main precision observables are now available up to O(alpha^2 mt^2/mw^2). The new results imply a significant reduction of the theoretical uncertainty and can have a sizable impact on the determination of the effective sine.
At a linear collider of the next generation the large event rates expected from Bhabha and Møller scattering may be used to determine simultaneously sin^2θ_w and the polarization of both beams with very high accuracy. These measurements can be performed in parallel to the other tasks of the linear collider as a free by-product. A high degree of polarization and a good polar angle coverage of the detectors turn out to be major assets.
Leading QCD vacuum polarization contributions to the electroweak parameter $δρ$ 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 $δρ$ is expressed in terms of the top-quark pole mass and its absence when the $\msbar$ running mass is employed. The calculations are applied to estimate higher order QCD contributions to $δρ$.
Recent developments in the field of high precision calculations in the Standard Model are illustrated with particular emphasis on the evidence for radiative corrections and on the estimate of the theoretical error in perturbative calculations.