gThe
hadronic cross section measurement at KLOEh
Debora. Leone
Abstract:
KLOE
uses the radiative return to measure the hadronic cross section e⁺e⁻¨ƒÎ⁺ƒÎ⁻ƒÁ 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 pb⁻¹ collected in 2001.
The results are compared with
the
pion from factor determined in ƒÑ⁻¨ƒÎ⁻ƒÎ⁰ƒË_ƒÑdecay.