Scalar Nonets in Pole-Dominated QCD Sum Rules

TL;DR

This paper uses advanced QCD sum rules to analyze light scalar mesons, supporting a tetraquark structure for isosinglets but leaving the octet classification inconclusive.

Contribution

It performs a detailed QCD sum rule analysis up to dimension 12 for scalar nonets, including flavor dynamics and SU(3) effects, to clarify their tetraquark nature.

Findings

Supports tetraquark structure for isosinglet scalars.

Differences in SU(3) singlet and octet states are due to annihilation diagrams.

Analysis retains pole dominance with high-dimension operator expansion.

Abstract

The light scalar nonets are studied using the QCD sum rules for the tetraquark operators. The operator product expansion for the correlators is calculated up to dimension 12 and this enables us to perform analyses retaining sufficient pole-dominance. To classify the light scalar nonets, we investigate the dependence on current quark mass and flavor dynamics. Especially, to examine the latter, we study separately SU(3) singlet and octet states, and show that the number of annihilation diagrams is largely responsible for their differences, which is also the case even after the inclusion of the finite quark mass. Our results support the tetraquark picture for isosinglets, while that for octets is not conclusive yet.