Observation of a00 (980)-f0 (980) Mixing

Abstract

We report the first observation of a00(980)-f0(980) mixing in the decays of J/ψ→φf0(980)→φa00(980)→φηπ0 and χc1→a00(980)π0→f0(980)π0→π+π-π0, using data samples of 1.31×109 J/ψ events and 4.48×108 ψ(3686) events accumulated with the BESIII detector. The signals of f0(980)→a00(980) and a00(980)→f0(980) mixing are observed at levels of statistical significance of 7.4σ and 5.5σ, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, ga0K+K- and gf0K+K-, are estimated. The results improve the understanding of the nature of a00(980) and f0(980).