Measurement of the Pion Formfactor with KLOE and Study of the Reaction f0(980) to pi+pi-

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At the Frascati phi-factory DAPHNE the pion formfactor is measured by means of the 'radiative return', i.e. by using events in which one of the collider electrons (positrons) has radiated an initial state radiation photon, lowering in such a way the invariant mass Mₚipi of the two-pion-system. In a recent publication of the KLOE collaboration the initial state radiation photon had been required to be at small polar angles with respect to the beam axis. We are presenting results from a new and complementary analysis in which the photon is tagged at large polar angles. Only like this the threshold region Mₚipi²<0.35 GeV² becomes accessible. Moreover, the final state pi+pi-gamma allows to study the phi radiative decay into the scalar particle f₀(980) with f₀(980) → pi+pi-. For the first time the two-pion mass spectrum could be fitted with different theoretical models for the description of this phi radiative decay.