A determination of the QED coupling at the $Z$ pole
Abstract
We critically examine the evaluation of the hadronic contribution to the running of the QED coupling, , from to . Using data for hadrons we find that , as compared to the existing value of .
Cite
@article{arxiv.hep-ph/9411377,
title = {A determination of the QED coupling at the $Z$ pole},
author = {A. D. Martin and D. Zeppenfeld},
journal= {arXiv preprint arXiv:hep-ph/9411377},
year = {2009}
}
Comments
We have made refinements to the calculation of the contribution to $\alpha(M_Z^2)$ from the $\pi^+\pi^-$ production, and from the region just above the $\psi$ resonances, including, in particular, a study of the implications of the Crystal Ball data for $R$. These refinements slightly reduce the value of $\alpha(M_Z^2)^{-1}$ from $129.10\pm 0.06$ to $128.99\pm 0.06$. Standard Latex, 12 pages. Four uufiled postscript files included. Compressed postscript version with figures available via anonymous ftp at ftp://phenom.physics.wisc.edu/pub/preprints/current/