The inverse amplitude method is used to unitarize the two-loop ππ scattering amplitudes of SU(2) chiral perturbation theory in the $I=0,J=0,I=1,J=1,$ and $I=2,J=0\mathrm{}$ channels. An error analysis in terms of the low energy one-loop parameters $l_{1,2,3,4}$ and existing experimental data is undertaken. A comparison to standard resonance saturation values for the two-loop coefficients $b_{1,2,3,4,5,6}$ is also carried out. Crossing violations are quantified and the convergence of the expansion is discussed.

• Received 10 September 2001

DOI:https://doi.org/10.1103/PhysRevD.65.036002