A Non-Perturbative Chiral Approach for Meson-Meson Interactions

TL;DR

This paper introduces a non-perturbative approach combining chiral symmetry constraints and unitarity to effectively describe meson-meson interactions up to 1.2 GeV, extending the applicability of Chiral Perturbation Theory beyond its usual energy range.

Contribution

It develops a novel non-perturbative method using the inverse amplitude expansion, fitted to experimental data, to improve meson interaction modeling at higher energies.

Findings

Good agreement with experimental data

Extended energy range for chiral perturbation theory

Effective description of meson-meson interactions

Abstract

A non-perturbative method which combines constraints from chiral symmetry breaking and coupled channel unitarity is used to describe meson-meson interactions up to \sqrt{s}\lesssim 1.2 GeV, extending in this way the range of applicability of the information contained in Chiral Perturbation Theory (\chi PT), since this perturbative series is typically restricted to \sqrt{s}\lesssim 500 MeV. The approach uses the O(p^2) and O(p^4) \chiPT Lagrangians. The seven free parameters resulting from the O(p^4) Lagrangian are fitted to the experimental data. The approach makes use of the expansion of T^{-1} instead of the amplitude itself as done in \chiPT. The former expansion is suggested by analogy with the effective range approximation in Quantum Mechanics and it appears to be very useful. The results, in fact, are in good agreement with a vast amount of experimental analyses.