Observation of $a^{0}_{0}(980)$-$f_{0}(980)$ Mixing

TL;DR

This paper reports the first observation of mixing between the scalar mesons $a^{0}_{0}(980)$ and $f_{0}(980)$, providing new insights into their nature through decay analysis of $J/ o o o$ and $\\chi_{c1} o o$ processes.

Contribution

It presents the first experimental evidence of $a^{0}_{0}(980)$-$f_{0}(980)$ mixing and measures their mixing intensities and related coupling constants.

Findings

Significant signals of meson mixing observed at 7.4σ and 5.5σ levels.

Measured branching fractions and mixing intensities.

Constraints on coupling constants $g_{a_{0}K^{+}K^{-}}$ and $g_{f_{0}K^{+}K^{-}}$.

Abstract

We report the first observation of $a^{0}_{0}(980)$-$f_{0}(980)$ mixing in the decays of $J/\psi\to\phi f_{0}(980)\to\phi a^{0}_{0}(980)\to\phi\eta\pi^{0}$ and $\chi_{c1}\to a^{0}_{0}(980)\pi^{0}\to f_{0}(980)\pi^{0}\to\pi^{+}\pi^{-}\pi^{0}$, using data samples of $1.31\times10^{9}$ $J/\psi$ events and $4.48\times10^{8}$ $\psi(3686)$ 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 $7.4\sigma$ and $5.5\sigma$, 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 $f_{0}(980)$.