Search for a vector gauge boson in phi meson decays with the KLOE detector

TL;DR

This study searches for a hypothetical light dark force mediator, called U, in phi meson decays using the KLOE detector, setting new limits on its coupling strength across a broad mass range.

Contribution

First search for the U boson in phi meson decays with KLOE, establishing upper limits on its coupling over a wide mass spectrum.

Findings

No evidence of the U boson was observed.

Set upper limits on the coupling ratio alpha'/alpha.

Excluded U boson masses between 5 and 470 MeV at specified coupling levels.

Abstract

The existence of a light dark force mediator has been tested with the KLOE detector at DAPHNE. This particle, called U, is searched for using the decay chain phi-->etaU, eta-->pi+pi-pi0, U-->e+e-. No evidence is found in 1.5 fb-1 of data. The resulting exclusion plot covers the mass range 5<M_U<470 MeV, setting an upper limit on the ratio between the U boson coupling constant and the fine structure constant, alpha'/alpha, of <= 2x10^-5 at 90% C.L. for 50<M_U<420 MeV.