Detection of phi --> eta' photon, phi --> eta photon in pi+ pi- three photons final state with KLOE at DAFNE

TL;DR

This paper reports precise measurements of the branching ratios for phi meson decays into eta and eta' photons using KLOE data, leading to improved determinations of the mixing angle and decay probabilities.

Contribution

The study provides the most accurate measurement of BR(phi -->eta' photon) and refines the phi-eta-eta' mixing angle using data from DAFNE.

Findings

Measured BR(phi -->eta' photon): (6.8 +- 0.6 +-0.5) x 10^-5

BR ratio of phi-->eta' to phi-->eta: (5.3 +- 0.5 +- 0.3) x 10^-3

Determined mixing angle: 40 +1.7 -1.5 degrees

Abstract

KLOE has collected about 30 pb^-1 in year 2000 at the DAFNE collider, which yields the largest population of phi meson radiative decays studied so far. We present the result obtained for phi-->eta photon and phi -->eta' photon: the ratio of these two BR's has been measured to be (5.3 +- 0.5 +- 0.3) times 10^-3, leading to a very accurate determination of the mixing angle in the flavor basis (40 +1.7 -1.5 degrees) and to the most accurate determination of BR(phi -->eta' photon) to date: (6.8 +- 0.6 +-0.5) times 10^-5.