Speakers
Caterina Bloise
(Istituto Nazionale Fisica Nucleare (IT))
Caterina Bloise
(Laboratori Nazionali di Frascati (LNF))
Description
The V-->Pgamma Dalitz decays, associated to internal conversion
of the photon into a lepton pair, are not well described by the
Vector Meson Dominance (VMD) models, as in the case of the
process omega --> pi0 mu+ mu-, measured by the NA60 collaboration.
The only existing data on phi --> eta e+ e- come from the SND
experiment, which has measured the Mee invariant mass distribution
on the basis of 213 events. At KLOE, a detailed study of this decay
has been performed using both eta-->pi+pi-pi0 and eta-->pi0pi0pi0
final states. Simple analysis cuts provide clean signal events
(about 14000 and 30000, respectively), with a residual background
contamination of 2-3%.
We have also studied the decay phi --> pi0 e+ e-, where no data
are available on transition form factor. Dedicated analysis cuts
strongly reduce the main background component of Bhabha events to
~20%, leading to ~4000 signal events in the whole KLOE data set.
The gamma-gamma couplings and partial widths of mesons provide
information about their structure and can be measured in the
e+e- --> e+e-gamma*gamma* --> e+e-X processes. The study of
gamma*gamma* --> eta will be discussed. The data sample consists
of an integrated luminosity of 240 pb-1 of data taken at the
center of mass energy SQRT(s)=1 GeV - where backgrounds from phi
decays are suppressed - without tagging of the e+e- in the final
state. The measurement of the cross section for the reaction
gamma*gamma* --> eta in the two decay channels eta-->pi+pi-pi0
and eta-->3pi0, with independent systematic uncertainties,
together with the extraction of the eta-->gammagamma width, will
be presented.
Primary author
Fabio Bossi
(Laboratori Nazionali di Frascati (LNF))
