EPJ Web of Conferences 81, 02017 (2014)
https://doi.org/10.1051/epjconf/20148102017

Measurement of the transition form factor in ϕ → ηe⁺e ⁻ and ϕ → π⁰e⁺e⁻ decays at KLOE

Laboratori Nazionali di Frascati - INFN -

^a e-mail: ivano.sarra@lnf.infn.it

Published online: 26 November 2014

Abstract

In this work we present a study of the Dalitz decay ϕ → ηe⁺e⁻, with η → π⁰π⁰π⁰, performed using 1.7 fb⁻¹ of e⁺e⁻ collisions collected at KLOE in the 2004-2005 data taking period. The resulting branching fraction is: BR(ϕ → ηe⁺e⁻) = (1.075 ± 0.007(stat.) ± 0.038(norm.)) × 10⁻⁴. We have also studied the invariant mass of the dilepton system, extracting the slope of the transition form factor: b _ϕη =(1.17 ± 0.10 _−0.11^+0.07) GeV⁻². The ϕ → π⁰e⁺e⁻ rare decay is also being studied using the same data sample. The branching ratio will be measured, with a consistent reduction of the actual total uncertainty. The double off shell π⁰ Transition Form Factor will also be measured for the first time in the time-like region, with the momentum transfer given by the e⁺e⁻ invariant mass.