TTP01-13 NLO QED corrections to ISR in $e^+ e^-$ annihilation and the measurement of $\sigma(e^+ e^- \rightarrow hadrons)$ using tagged photons

TTP01-13 NLO QED corrections to ISR in $e^+ e^-$ annihilation and the measurement of $\sigma(e^+ e^- \rightarrow hadrons)$ using tagged photons

TTP01-13 NLO QED corrections to ISR in $e^+ e^-$ annihilation and the measurement of $\sigma(e^+ e^- \rightarrow hadrons)$ using tagged photons

The leptonic tensor for the process $e^+ e^- \rightarrow \gamma+\gamma^*$, which describes the next-to-leading order virtual and soft QED corrections to initial state radiation in $e^+ e^-$ annihilation with emission of an extra virtual photon decaying into hadrons, is calculated. A Monte Carlo generator for the reaction $e^+ e^- \rightarrow \gamma + \pi^+ \pi^-$ has been set up which includes these corrections. It thus describes configurations where the for the reaction $e^+ e^- \rightarrow \gamma + \pi^+ \pi^-$ has been set up which includes these corrections. It thus describes configurations where the invariant mass of the hadrons plus photon is very close to $\sqrt{s}$. Predictions for cms energies of 1 to 10 GeV, corresponding to the energies of DAPHNE and B-meson factories, are presented. The possibility for an accurate measurement using tagged photons of $\sigma(e^+ e^- \rightarrow hadrons)$, which plays an important role in the theoretical description of the muon anomalous magnetic moment and the running of the electromagnetic coupling, is discussed.

 G. Rodrigo, A. Gehrmann, M. Guilleaume and J. H. K\“uhn Eur. Phys. J. C22 81-88 2001 PDF PostScript arXiv