Jul 20 – 27, 2011
Alpes Congrès - Alpexpo
Europe/Paris timezone

{\bf KLOE measurement of the $\sigma(e^+e^-\to\pi^+\pi^-(\gamma))$ with Initial State Radiation and the $\pi\pi$ contribution to the muon anomaly}

Jul 23, 2011, 9:30 AM
Stendhal (Alpes Congrès - Alpexpo)


Alpes Congrès - Alpexpo

Parallel session talk Top and Electroweak Physics Top and Electroweak Physics


Dr Graziano Venanzoni (INFN - Laboratori Nazionali di Frascati)


The KLOE experiment at the $\phi$ factory DA$\Phi$NE in Frascati (near Rome) is the first to have employed Initial State Radiation (ISR) to precisely determine the $e^+e^-\to\pi^+\pi^-(\gamma)$ cross section below 1 GeV. Such a measurement is particularly important to test the Standard Model calculation for the (g-2) of the muon, where a long standing 3$\sigma$ discrepancy is observed. In 2005 and 2008 KLOE has published a measurement of the $\pi^+\pi^-$ cross section with the photon emitted at small angle, and a new independent measurement with the photon emitted at large angle using data taken in 2006 at a collision energy of 1 GeV ({\it i.e.} 20 MeV below the $\phi$-peak) has been accepted for publication. While these measurements were normalized to the DA$\Phi$NE luminosity using large angle Bhabha scattering, a new analysis has been performed which derives the pion form factor directly from the $\pi^+\pi^-\gamma(\gamma)/\mu^+\mu^-\gamma(\gamma)$ ratio. We present the KLOE results and discuss future prospects for these measurements as well as their impact on the evaluation of the hadronic contribution to the muon anomaly.

Primary author

Dr Graziano Venanzoni (INFN - Laboratori Nazionali di Frascati)

Presentation materials