Light scalars in semi-leptonic decays of heavy quarkonia

Abstract

We study the mechanism of production of the light scalar mesons in the $D_s^+\toπ^+π^- e^+ν$ decays: $D_s^+\to s\bar s e^+ν\to [σ(600)+f_0(980)] e^+ν\toπ^+π^- e^+ν$, and compare it with the mechanism of production of the light pseudoscalar mesons in the $D_s^+\to (η/η') e^+ν$ decays: $D_s^+\to s\bar s e^+ν\to (η/η')e^+ν$. We show that the $s\bar s\toσ(600)$ transition is negligibly small in comparison with the $s\bar s\to f_0(980)$ one. As for the the $f_0(980)$ meson, the intensity of the $s\bar s\to f_0(980)$ transition makes near thirty percent from the intensity of the $s\bar s\toη_s$ ($η_s=s\bar s$) transition. So, the $D_s^+\toπ^+π^- e^+ν$ decay supports the previous conclusions about a dominant role of the four-quark components in the $σ(600)$ and $f_0(980)$ mesons.