  Composite Higgs models are an intriguing scenario in which the Higgs particle
is identified as a pseudo Nambu-Goldstone boson associated with spontaneous
breaking of some global symmetry above the electroweak scale. They would
predict new resonances at high energy scales, some of which can appear at
multi-TeV scales. In such a case, analogies with pion physics in QCD that a
sizable phase shift is predicted in pion-pion scattering processes might help
us to evaluate scales of the resonances.In this paper, we discuss two
complementary approaches to investigate the compositeness scale in minimal
composite Higgs models. First, we discuss the bound on vector boson scattering
from perturbative unitarity, and we evaluate the phase shift of the scattering
amplitude, assuming that the same fitting function can be applied as the case
in the pion physics. We then obtain the relation between possible phase shifts
and promising new resonance scales. We also investigate the possibility to
measure the phase shift at LHC and the future hadron colliders. Second, we
classify deviations in Higgs coupling constants from the standard model
predictions in various kinds of the minimal composite Higgs models. We then
discuss a possibility to discriminate a specific minimal composite Higgs model
from the other models with extended Higgs sectors by utilizing deviation
patterns in the Higgs boson couplings by future precision measurements.
