Pi pi scattering lengths at O(p^6): resonance estimates

Understand

In a previous paper, some deviations were found in the O(p^6) low-energy constants that contribute to the pi pi-scattering lengths.

• This work completes the study of all the relevant couplings (r_1, ...
• r_6, r_S2).
• We also perform a reanalysis of the hadronical inputs used for the estimation (resonance masses, widths...), checking the impact of the input uncertainties on the determinations of the chiral couplings and the scattering lengths a^I_J.