Light scalars in semi-leptonic decays of heavy quarkonia

TL;DR

This paper investigates the production mechanisms of light scalar mesons in semileptonic heavy quarkonium decays, highlighting the dominant four-quark components in the scalar mesons' structure.

Contribution

It provides a comparative analysis of scalar and pseudoscalar meson production in D_s^+ decays, emphasizing the significant role of four-quark components in scalar mesons.

Findings

The sar s o f_0(980) transition is much stronger than sar s o \sigma(600).

The sar s o f_0(980) transition accounts for about 30% of the sar s o ext{meson} transition intensity.

The decay data supports the four-quark model for \sigma(600) and f_0(980).

Abstract

We study the mechanism of production of the light scalar mesons in the $D_s^+\to\pi^+\pi^- e^+\nu$ decays: $D_s^+\to s\bar s e^+\nu\to [\sigma(600)+f_0(980)] e^+\nu\to\pi^+\pi^- e^+\nu$, and compare it with the mechanism of production of the light pseudoscalar mesons in the $D_s^+\to (\eta/\eta') e^+\nu$ decays: $D_s^+\to s\bar s e^+\nu\to (\eta/\eta')e^+\nu$. We show that the $s\bar s\to\sigma(600)$ 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 $s\bar s\to\eta_s$ ($\eta_s=s\bar s$) transition. So, the $D_s^+\to\pi^+\pi^- e^+\nu$ decay supports the previous conclusions about a dominant role of the four-quark components in the $\sigma(600)$ and $f_0(980)$ mesons.