Mode Fraction (Γi /Γ) Confidence level

η IG (JPC) = 0+(0−+) We have omitted some results that have been superseded by later experiments. The omitted results may be found in our 1988 edition Physics Letters B204 (1988). η MASS Recent measurements resolve the obvious inconsistency in previous η mass measurements in favor of the higher value first reported by NA48 (LAI 02). We use only precise measurements consistent with this higher mass value for our η mass average. VALUE (MeV) EVTS DOCUMENT ID TECN COMMENT 547.862±0.017 OUR AVERAGE 547.865±0.031±0.062 NIKOLAEV 14 CRYB γp → pη 547.873±0.005±0.027 1M GOSLAWSKI 12 SPEC d p → 3He η 547.874±0.007±0.029 AMBROSINO 07B KLOE e+ e − → φ → ηγ 547.785±0.017±0.057 16k MILLER 07 CLEO ψ(2S) → J/ψη 547.843±0.030±0.041 1134 LAI 02 NA48 η → 3pi0 • • • We do not use the following data for averages, fits, limits, etc. • • • 547.311±0.028±0.032 1 ABDEL-BARY 05 SPEC d p → 3He η 547.12 ±0.06 ±0.25 KRUSCHE 95D SPEC γp → ηp, threshold 547.30 ±0.15 PLOUIN 92 SPEC d p → 3He η 547.45 ±0.25 DUANE 74 SPEC pi − p → n neutral