Excited-state contribution to the axial-vector and pseudoscalar correlators with two extra pions

We study multiparticle-state contributions to the QCD two-point functions of the axial-vector and pseudoscalar quark bilinears in a finite spatial volume. For sufficiently small quark masses one expects three-meson states with two additional pions at rest to have the lowest total energy after the ground state. We calculate this three-meson-state contribution using chiral perturbation theory. We find it to be strongly suppressed and too small to be seen in present-day lattice simulations.