gNew results from BaBar on e+e- annihilation through radiative returnh

 

Michel Davier (LAL-Orsay)

 

Abstract:

 

New results are presented on e+e- annihilation into pi+ pi- pi0

and 2pi+ 2pi- extracted from the corresponding initial state processes.

They have been studied at a center-of-mass energy near the Y(4S)

resonance using a 89.3 fb-1 data sample collected with the BaBar

detector at the PEP-II collider at SLAC. From the measured

3pi mass spectrum we have obtained the products of branching fractions

for the omega and phi mesons,

B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and B(phi -->

e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5,

and evaluated the e+e---> pi+ pi- pi0 cross section for the e+e- center-of-mass

energy range1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0

gamma events have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)

=(2.18 +/- 0.19)% has been measured. About 60000 fully reconstructed events

have been selected in the 4pi channel in the range of c.m.s. energy

from 0.6 to 4.5 GeV. The cross sections for identified 2K 2pi and 4K final states

are also presented. The J/psi gamma signal allows to measure decay rates

of J/psi to 4pi, 2K 2pi and 4K with best to date accuracy.