Observation of $a_0^0(980)$-$f_0(980)$ Mixing

Abstract

We report the first observation of $a_0^0(980)$-$f_0(980)$ mixing in the decays of $J/\ddot{I}ˆ\to \ddot{I}•f_0(980)\to \ddot{I}•a_0^0(980)\to \ddot{I}•\hat{I}\cdot \ddot{I}{€}^0$ and $\ddot{I}{‡}_{c1}\to a_0^0(980)\ddot{I}{€}^0\to f_0(980)\ddot{I}{€}^0\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$, using data samples of $1.31\times 10^9$ $J/\ddot{I}ˆ$ events and $4.48\times 10^8$ $\ddot{I}ˆ(3686)$ events accumulated with the BESIII detector. The signals of $f_0(980)\to a_0^0(980)$ and $a_0^0(980)\to f_0(980)$ mixing are observed at levels of statistical significance of $7.4\ddot{I}ƒ$ and $5.5\ddot{I}ƒ$, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, $g_{a_0{K}^{+}{K}^{-}}$ and $g_{f_0{K}^{+}{K}^{-}}$, are estimated. The results improve the understanding of the nature of $a_0^0(980)$ and $f_0(980)$.

7 pages, 4 figures, 2 tables