Bonn 2010 – wissenschaftliches Programm
HK 4.3: Gruppenbericht
Montag, 15. März 2010, 17:30–18:00, HG III
Measurement of the pion form factor between 0.1 and 0.85 GeV2 with the KLOE experiment — •Stefan E. Müller — Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, J.-J.-Becher-Weg 45, 55128 Mainz
The KLOE experiment at the DAΦNE e+e− collider in Frascati has performed a new measurement of the pion form factor |Fπ|2 in the mass range between 0.1 < Mππ2 < 0.85 GeV2 using events taken at √s= 1 GeV with a photon emitted at large polar angles in the initial state. This “radiative return” to the ρ and ω resonances allows to access the energy region below the nominal DAΦNE energy, which is fixed to values close to Mφ. The new measurement extends the Mππ2 region covered by KLOE ISR measurements of the pion form factor down to the two pion production threshold, and allows to determine via a dispersion integral the value of the dipion contribution to the muon anomalous magnetic moment.
The measurement and its impact on the muon anomalous magnetic moment will be presented in the talk, and an outlook on future measurements of the pion form factor will be given. In addition, the role of angular asymmetries on validating phenomenological models for pionic final state radiation and scalar mesons will be discussed.