gNew results
from BaBar on e+e-
annihilation through radiative returnh
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.