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+ | ====== TTP95-13 QCD Corrections from Top Quark to Relations between Electroweak Parameters to Order $\as^2$ ====== | ||

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+ | <hidden TTP95-13 QCD Corrections from Top Quark to Relations between Electroweak Parameters to Order $\as^2$ > The vacuum polarization functions $\Pi(q^2)$ of charged and neutral | ||

+ | gauge bosons which arise from top and bottom quark loops lead to | ||

+ | important shifts in relations between electroweak parameters | ||

+ | which can be measured with ever-increasing precision. The large | ||

+ | mass of the top quark allows approximation of these functions through | ||

+ | the first two terms of an expansion in $M_Z^2/M_t^2$. | ||

+ | The first three terms of the Taylor series of $\Pi(q^2)$ are | ||

+ | evaluated analytically up to order $\as^2$. | ||

+ | The first two are required to derive the approximation, the | ||

+ | third can be used to demonstrate the smallness of the neglected terms. | ||

+ | The paper | ||

+ | improves earlier results | ||

+ | based on the leading term $\propto G_F M_t^2 \as^2$. | ||

+ | Results for the subleading | ||

+ | contributions to $\dr$ and the effective mixing angle $\sineff$ are presented. | ||

+ | </hidden> | ||

+ | |**K.G. Chetyrkin, J.H. Kuehn, M. Steinhauser** | | ||

+ | |** Phys. Rev. Lett. 75 3394-3397 1995 ** | | ||

+ | | {{preprints:1995:ttp95-13.pdf|PDF}} {{preprints:1995:ttp95-13.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9504413|arXiv]] | | ||

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