Chiral dynamics in U(3) unitary chiral perturbation theory

TL;DR

This paper performs a comprehensive one-loop analysis of meson-meson scattering and form factors within U(3) chiral perturbation theory, incorporating resonance fields and QCD anomalies, to explore scalar meson dynamics and spectrum.

Contribution

It introduces a complete one-loop unitarized calculation in U(3) chiral perturbation theory including explicit resonance fields and anomaly effects, advancing understanding of scalar meson dynamics.

Findings

Successful description of meson-meson scattering data

Insights into scalar resonance spectrum and sum rules

Validation of scalar dynamics within QCD framework

Abstract

We perform a complete one-loop calculation of meson-meson scattering, and of the scalar and pseudoscalar form factors in U(3) chiral perturbation theory with the inclusion of explicit resonance fields. This effective field theory takes into account the low-energy effects of the QCD U_A(1) anomaly explicitly in the dynamics. The calculations are supplied by non-perturbative unitarization techniques that provide the final results for the meson-meson scattering partial waves and the scalar form factors considered. We present thorough analyses on the scattering data, resonance spectroscopy, spectral functions, Weinberg-like sum rules and semi-local duality. The last two requirements establish relations between the scalar spectrum with the pseudoscalar and vector ones, respectively. The Nc extrapolation of the various quantities is studied as well. The fulfillment of all these non-trivial aspects of the QCD dynamics by our results gives a strong support to the emerging picture for the scalar dynamics and its related spectrum.