# Europhysics Conference on High-Energy Physics 2011

20-27 July 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}

23 Jul 2011, 09:30
15m
Stendhal (Alpes Congrès - Alpexpo)

### Stendhal

#### Alpes Congrès - Alpexpo

Parallel session talk Top and Electroweak Physics

### Speaker

Dr Graziano Venanzoni (INFN - Laboratori Nazionali di Frascati)

### Description

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

 Transparents