SEMINAR   Thursday, June 5th - h. 15:00 Aula Seminari (A34)    E. Solodov BINP, Novosibirsk Study of the low energy electron-positron cross sections and   hadron spectroscopy using hard photon initial state radiation   emission at BaBar  Abstract An analysis of processes with initial state radiation (ISR) has been performed using data collected by the BaBar experiment at the PEP-II asymmetric electron-positron collider, corresponding to an integrated luminosity of about 90 fb^-1. Muon pairs and multi-hadron final states accompanied by a detected ISR photon were selected. The invariant mass of the di-muon or hadronic system determines the virtual photon energy; the cross-sections can be compared with direct electron-positron cross sections measured at lower center-of-mass energy. Preliminary results for KK, ppbar, KKpi0, 3pi, 4picross sections are presented and discussed in terms of low energy hadron spectroscopy. This technique gives also access to J/Psi production and to the measurement of the branching ratios of J/Psi decays to mu+mu-, 3pi, 2K2pi and 4K, with competitive accuracy. Preliminary results are also discussed for the ratio R of the electron-positron cross section to hadrons and to mu+mu-pairs.