η Physics with the crystal ball detector

Abstract

The experimental results obtained with the Crystal Ball detector for the physics of η-meson decays are reviewed. The η → 3π 0 Dalitz plot slope and the η → π 0 γγ decay width are measured with a high accuracy using 3 × 107 η decays. Upper limits on the η → 3γ, η → 2π 0 γ, and η → 3π 0 γ C-forbidden decays are found. The sensitivity of these upper limits to C violation is estimated. An upper limit on the η → 4π 0 C P-forbidden decay is found for the first time and the sensitivity of this value to C P violation is estimated.