Role of the $a_{0}(980), f_{0}(980)$ resonances in $\eta \to 3\pi$ from the Khuri-Treiman formalism

International audienceThe chiral expansion of the eta -> 3pi decay amplitude at NLO fails to reproduce the recent high accuracy measurements of the Dalitz plot parameters. We reconsider the idea of employing the chiral expansion in an unphysical region surrounding the Adler zero and then deducing the amplitude in the physical region using the Khuri-Treiman dispersive formalism. We further present an extension of this formalism which takes into account KK̄ inelastic rescattering effects and thus provides a realistic description of the double a_0(980), f_0(980) resonance effect. We evaluate how the influence of these resonances propagates down to the low-energy decay region and show that it is significant, in particular for the eta -> 3pi^0 decay, and improve the agreement of the predicted Dalitz plot parameters with experiment