The radiative return at - and B-factories: FSR at next-to-leading order
Institute of Physics, University of Silesia, 40007, Katowice, Poland
2 Institut für Theoretische Teilchenphysik, Universität Karlsruhe, 76128, Karlsruhe, Germany
3 Theory Division, CERN, 1211, Geneva 23, Switzerland
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The measurement of the pion form factor and, more generally, of the cross section for electron-positron annihilation into hadrons through the radiative return has become an important task for high luminosity colliders such as the - or B-meson factories. For a detailed understanding and analysis of this reaction, the construction of a Monte Carlo program, PHOKHARA, has been undertaken. Version 2.0 was based on a next-to-leading order (NLO) treatment of the corrections from initial-state radiation (ISR). In the present paper a further extension of PHOKHARA (version 3.0) is described, which incorporates NLO corrections to final-state radiation (FSR). The impact of combined ISR and FSR on various distributions is investigated and methods are presented which will allow the extraction of the form factor, and even give access to inclusive photon emission due to FSR. The dependence of the results on the model for FSR is discussed and the impact of this contribution on the anomalous magnetic moment of the muon is evaluated.
© Springer-Verlag, 2004