  The naturalness problem in the Higgs sector finds a popular solution in
composite Higgs models. In such theories the Higgs boson emerges as the
pseudo-Nambu-Goldstone boson associated with the breaking of a global symmetry
realised in a new, strongly interacting sector. We address a model arising in
this context, a SU(4) gauge theory with fermions in two distinct
representations. We present a novel lattice study of this theory, in which we
address the non-perturbative reconstruction of spectral densities from lattice
correlators.
