Relevance of final state interactions in eta'->eta pi pi decays

TL;DR

This paper investigates the impact of final state interactions on the eta'->eta pi pi decay, demonstrating that incorporating unitarity effects via chiral theories aligns predictions with experimental data.

Contribution

It provides a detailed analysis of final state interactions in eta' decays using U(3) Chiral Perturbation Theory and Resonance Chiral Theory, emphasizing the importance of pion loop unitarity effects.

Findings

Inclusion of unitarity effects improves agreement with experimental Dalitz plot data.

Final state interactions significantly influence decay distributions.

Predictions now match experimental measurements after accounting for these effects.

Abstract

A study of the eta'->eta pi pi Dalitz plot distribution is presented in this talk. The size of the branching ratio is properly understood within U(3) Chiral Perturbation Theory and Resonance Chiral Theory, in the framework of the 1/Nc expansion. Nonetheless, unitarity effects of pion loops must be incorporated in order to achieve an appropriate description of the Dalitz slope parameters. After taking the final state interactions into account, our predictions become now in agreement with the available experimental measurements, although some clear differences show up with respect to previous theoretical estimates.