New resonance scale and fingerprint identification in minimal composite Higgs models

Abstract

Composite Higgs models are intriguing scenarios 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 the pion physics in QCD, where 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 as one in the case of the pion physics can be applied. 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.