出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The KLOE experiment at the electron-positron collider DAFNE has recently proven the feasibility
of using initial state radiation (ISR) in e+e annihilation for precision measurements
of hadronic cross section. This new method, dubbed Radiative Return, allows us to measure
hadronic cross sections for energies M2(hadron) < s at particle factories which operate at xed
centre-of-mass energy s. In the recently published KLOE measurement of the pion form factor,
events had been collected where the ISR photon is emitted at small polar angles, which reduces
the background from nal state radiation (FSR) but leads to a suppression of the threshold region
M2 pp < 0:35 GeV2. We present here a complementary analysis using events with ISR photons
emitted at large polar angles. Photon tagging is possible in this case (contrary to the small photon
polar angle analysis) and the threshold region becomes accessible. Preliminary results are presented,
as well as a measurement of the forward-backward asymmetry, which allows a test of the
FSR model used for the description of the photon radiation from pions.
