  In this letter, we construct the recursion relations for one-loop planar
integrands in the SU(N) non-linear sigma model. This generalizes the soft
recursions for tree-level amplitudes in a variety of quantum field theories
with special soft limits. The main ingredient is the definition of the one-loop
planar integrand, which is fixed by cuts in the sense of generalized unitarity
and by requiring the Adler zero on all external legs. We show that this does
not uniquely fix the integrand, so additional constraints on the soft behavior
of the loop momentum have to be imposed. Our work is the first step in
extending modern amplitudes methods for loop amplitudes to effective field
theories with special soft limits.

High Energy Physics - Theory;High Energy Physics - Phenomenology