Approximating chiral SU(3) amplitudes

Understand

We construct large-N_c motivated approximate chiral SU(3) amplitudes of next-to-next-to-leading order.

• The amplitudes are independent of the renormalization scale.
• Fitting lattice data with those amplitudes allows for the extraction of chiral coupling constants with the correct scale dependence.
• The differences between approximate and full amplitudes are required to be at most of the order of N^3LO contributions numerically.