Sigma-assisted low scale composite Goldstone–Higgs

Artikel i vetenskaplig tidskrift, 2020

We show that the presence of a lightish scalar resonance, σ, that mixes with the composite Goldstone–Higgs boson can relax the typical bounds found in this class of models. This mechanism, inbred in models with a walking dynamics above the condensation scale, allows for a low compositeness scale f≳ 400 GeV, corresponding to a misalignment angle sθ≲ 0.6 , contrary to the common lore of a smaller angle. According to recent lattice results, the light σ emerges thanks to a near-conformal phase above the condensation scale, consistent to the requirements from flavour physics. We study this effect in a general way, showing that it appears in all cosets emerging from an underlying gauge-fermion dynamics, in the presence of top partial compositeness. The scenario is testable both on the Lattice and experimentally, as it requires the presence of a second broad Higgs-like resonance, below 1 TeV, that can be revealed at the LHC in the ZZ and tt¯ channels.