A Study of the Radiative Ke3 Decay and Search for Direct Photon Emission with the KLOE Detector

Kloe Collaboration

doi:10.1140/epjc/s10052-008-0634-2

paper

A Study of the Radiative Ke3 Decay and Search for Direct Photon Emission with the KLOE Detector

arXiv:0710.3993 · doi:10.1140/epjc/s10052-008-0634-2

Abstract

We present a measurement of the ratio R = Γ(\keg;\Estar>30\mev,\qstar>20^\circ) $/$ Γ(\kegf) $an d a f i r s t m e a s u r e m e n t o f t h e d i r ec t e mi ss i o n co n t r ib u t i o nin K L se mi l e pt o ni c d ec a y s . T h e m e a s u r e m e n t i s d o n e a tt h eD A F N E p hi - f a c t or y se l ec t in g p hi - > K L K S d ec a y s w i t h t h eK L O E d e t ec t or . W e u se 328 p b^{- 1}$ of data corresponding to about 3.5 million Ke3(g) events and about 9000 radiative events. Our result is R=(924 +/- 23(stat) +/-16(syst)10^{-5} for the branching ratio and X=-2.3 +/- 1.3(stat) +/- 1.4(syst) for the parameter describing direct emission.

8 pages, 7 figures