Structures of the $f_0(980)$, $a_0(980)$ mesons and the strong coupling constants $g_{f_0 K^+ K^-}$, $g_{a_0 K^+ K^-}$ with the light-cone QCD sum rules

Abstract

In this article, with the assumption of explicit isospin violation arising from the $f_0(980)-a_0(980)$ mixing, we take the point of view that the scalar mesons $f_0(980)$ and $a_0(980)$ have both strange and non-strange quark-antiquark components and evaluate the strong coupling constants $g_{f_0 K^+ K^-}$ and $g_{a_0 K^+ K^-}$ within the framework of the light-cone QCD sum rules approach. The large strong scalar-$KK$ couplings through both the $n\bar{n}$ and $s\bar{s}$ components $g^{\bar{n}n}_{f_0 K^+ K^-}$, $g^{\bar{s}s}_{f_0 K^+ K^-}$, $g^{\bar{n}n}_{a_0 K^+ K^-}$ and $g^{\bar{s}s}_{a_0 K^+ K^-}$will support the hadronic dressing mechanism, furthermore, in spite of the constituent structure differences between the $f_0(980)$ and $a_0(980)$ mesons, the strange components have larger strong coupling constants with the $K^+K^-$ state than the corresponding non-strange ones, $g_{f_0 K^+ K^-}^{\bar{s}s}\approx \sqrt{2}g_{f_0 K^+ K^-}^{\bar{n}n}$ and $g_{a_0 K^+ K^-}^{\bar{s}s}\approx \sqrt{2} g_{a_0 K^+ K^-}^{\bar{n}n}$. From the existing controversial values, we can not reach a general consensus on the strong coupling constants $g_{f_0 K^+ K^-}$, $g_{a_0 K^+ K^-}$ and the mixing angles.