NLO QED corrections to ISR in e+ e- annihilation and the measurement of σ(e+ e- \to hadrons) using tagged photons

Rodrigo, German; Ridder, Aude Gehrmann-De; Guilleaume, Marc; Kuhn, Johann H.

NLO QED corrections to ISR in e+ e- annihilation and the measurement of σ(e+ e- \to hadrons) using tagged photons

Authors

Rodrigo, German

Ridder, Aude Gehrmann-De

Guilleaume, Marc

Kuhn, Johann H.

Description

The leptonic tensor for the process $e^+ e^- \to γ+γ^*$, 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 $e^+ e^- \to γ+ π^+ π^-$ 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 $σ(e^+ e^- \to hadrons)$, which plays an important role in the theoretical description of the muon anomalous magnetic moment and the running of the electromagnetic coupling, is discussed.
8 pages, 5 figures, submitted to EPJ. The complete paper is also available at http://www-ttp.physik.uni-karlsruhe.de/Preprints/