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 — preprints:2008:ttp08-26 [2016/03/17 11:03] (current) Line 1: Line 1: + ====== TTP08-26 Two-loop QED hadronic corrections to Bhabha scattering ====== + + + <​hidden TTP08-26 ​ Two-loop QED hadronic corrections to Bhabha scattering > heoretical predictions for Bhabha scattering at the two-loop level require the inclusion of + ​hadronic vacuum polarization in the photon propagator. We present predictions for the contri + ​butions from reducible amplitudes which are proportional to the vacuum polarization $\pi(q^2 + )$ and from irreducible ones where the vacuum polarization appears in a loop representing ve + rtex or box diagrams. The second case can be treated by using dispersion relations with a we + ight function proportional to the $R$-ratio as measured in electron-positron annihilation in + to hadrons and kernels that can be calculated perturbatively. We present simple analytical f + orms for the kernels and, using two convenient parametrizations for the function $R(s)$, num + ​erical results for the quantities of interest. As a cross check we evaluate the correspondin + g corrections resulting from light and heavy lepton loops and we find perfect agreement with + previous calculations. For the hadronic correction our result are in good agreement with a + ​previous evaluation. + ​ + |**Johann H. K&​uuml;​hn and Sandro Uccirati** ​ | + |**  Nucl.Phys. ​ B806 300-326 2009  **  | + | {{preprints:​2008:​ttp08-26.pdf|PDF}} {{preprints:​2008:​ttp08-26.ps|PostScript}} [[http://​arxiv.org/​abs/​0807.1284|arXiv]] ​  | + | |