Hadronphysik mit Initial State Radiation (ISR) an BaBar
Dr. Miriam Fritsch (Inst. f. Kernphysik Mainz)

Hadronphysik mit Initial State Radiation (ISR) an BaBar

Measuring the inclusive hadronic cross section in e+e- is of major interest for the determination of the Standard Model prediction of the anomalous magnetic moment of the muon a_mu.
The hadronic contribution a_mu(had) can be derived from measured total cross sections of exclusive hadronic reactions with the help of a dispersion relation.
Decreasing the experimental uncertainties on these channels is of utmost importance to improve the Standard Model prediction. The reaction channel e+ e- to pi+ pi- has the biggest impact on the calculation.

This talk presents exclusive hadronic cross sections measured with the technique of Initial State Radiation (ISR). A huge dataset was taken with the BaBar detector at the B-factory PEP-II at SLAC (Stanford, USA), an electron-positron storage ring with fixed CM-energy of 10.58 GeV. Using the ISR method we get access to the energy range from the threshold up to 4.5 GeV. The first preliminary measurement of the pipi-channel and other channels important for the the muon anomaly will be presented.