Measurements of low energy e+e- hadronic cross sections and implications for the muon g-2

Numerous channels of the cross section e+e- --> hadrons have been measured by the BABAR experiment using the ISR method. For the pi+pi-(gamma) and K+K-(gamma) channels, BABAR has pioneered the method based on the ratio between the hadronic mass spectra and mu+mu-(gamma). Many systematic uncertainties cancel in the ratio, hence the precise measured cross sections. These measurements have been exploited for phenomenological studies, like the determination of the hadronic contribution to the anomalous magnetic moment of the muon (g-2)_mu.