Instanton effects on the twist-three light-cone distribution amplitudes of pion and light scalar mesons above 1GeV

TL;DR

This paper investigates how instanton effects influence the twist-3 light-cone distribution amplitudes of pions and scalar mesons above 1 GeV using QCD sum rules, revealing significant modifications and non-positive-definite behaviors.

Contribution

It introduces a single instanton approximation into the analysis of twist-3 LCDAs for specific mesons, highlighting the impact of instantons on their shape and properties.

Findings

Instanton effects significantly alter light-cone distribution amplitudes.

Twist-3 LCDAs become non-positive-definite within certain momentum ranges.

Low instanton density is necessary for the convergence of moments.

Abstract

By use of single instanton approximation the twist-3 light-cone distribution amplitudes of pion as well as the p-wave mesons, i.e., $f_{0}(1370)$, $K_{0}^{\ast}(1430)$ and $a_{0}(1450)$ are investigated within the framework of QCD moment sum rules with inclusion of instanton effects based on the valence quark model. Results show that there is much change on light-cone distribution amplitudes by the isospin- and chirality-dependent instanton contribution compared with the instanton-free ones. We find the intanton involved twist-3 LCDAs are non-positive-definite within some range of momentum fraction and there are rapid changes at two ends of momentum fraction. To guarantee the convergence of moments by the method in this work a low instanton density should be adopted, for instance $n_{c}=1/2\rm{fm^{-4}}$ is welcomed. Possible ingredients which might have impact on the results are briefly discussed. These light-cone distribution amplitudes may be helpful to analyze exclusive heavy flavored processes.