gThe hadronic cross section measurement at KLOEh

Debora. Leone

 

 

Abstract:

 

KLOE uses the radiative return to measure the hadronic cross section ee¨ƒÎƒÎƒÁ at DAƒ³NE. 

The energy of the machine is fixed to 1020 MeV, but the emission of one or more hard photons is

the initial state (ISR) reduces the collision energy, allowing us to cover the two pions invariant mass

squared ƒª²ƒÎƒÎ=ѕƒÎ, in the region from the two pions threshold to m²ƒÓ.  An extremely accurate

knowledge of experimental systematics, background, luminosity and, on theoretical side, a precise

decription of initial state radiation are needed to perform a competitive measurement. 

We present here the result of the analysis of 140 pb¹ collected in 2001.  The results are compared with

the pion from factor determined in ƒÑ¨ƒÎƒÎƒË_ƒÑdecay.