Goldstone boson scattering with a light composite scalar

The appearance of a light composite $0^+$ scalar resonance in nearly conformal gauge-fermion theories motivates further study the low energy structure these theories. To this end, we present nonperturbative lattice calculation s-wave scattering Goldstone bosons maximal-isospin channel SU(3) gauge theory with $N_f=8$ light, degenerate flavors. phase shift is measured both for different values underlying fermion mass and momentum. We examine effect flavor-singlet (reported earlier studies) on boson scattering, employing dilaton effective field (EFT) at tree level. EFT gives good description data, insofar as magnitude deviations between data are no larger than expected size next-to-leading order corrections EFT.