Fundamental composite (Goldstone) Higgs dynamics

Abstract

We provide a unified description, both at the effective and fundamental Lagrangian level, of models of composite Higgs dynamics where the Higgs itself can emerge, depending on the way the electroweak symmetry is embedded, either as a pseudo-Goldstone boson or as a massive excitation of the condensate. We show that, in general, these states mix with repercussions on the electroweak physics and phenomenology. Our results will help clarify the main differences, similarities, benefits and shortcomings of the different ways one can naturally realize a composite nature of the electroweak sector of the Standard Model. We will analyze the minimal underlying realization in terms of fundamental strongly coupled gauge theories supporting the flavor symmetry breaking pattern SU(4)/Sp(4) ∼ SO(6)/SO(5). The most minimal fundamental description consists of an SU(2) gauge theory with two Dirac fermions transforming according to the fundamental representation of the gauge group. This minimal choice enables us to use recent first principle lattice results to make the first predictions for the massive spectrum for models of composite (Goldstone) Higgs dynamics. These results are of the utmost relevance to guide searches of new physics at the Large Hadron Collider.

Flavour anomalies after the R K ∗ measurement

“…In view of the resulting breaking of the TC-chiral symmetry, the Higgs doublet H (identified with pseudo Goldstone bosons of the theory) and other composite scalars remain lighter. Lattice simulations [89][90][91] of the most minimal fundamental composite theories [92][93][94], without techni-scalars, have demonstrated the actual occurrence of chiral symmetry breaking with the relevant breaking pattern, and furthermore provided the spectrum of the spin one vector and axial techni-resonances with masses m V = 3.2(5) TeV/ sin θ and m A = 3.6(9) TeV/ sin θ where θ is the electroweak embedding angle to be determined by the dynamics, that must be smaller than about 0.2.…”

Gauge theories of partial compositeness: scenarios for Run-II of the LHC

“…The EW cosets above have been studied in many previous papers, see e.g. [39][40][41][42][43] for SU(4)/Sp(4), [34,44] for SU(4) × SU(4) /SU(4) D and [12,40,[45][46][47][48] for SU(5)/SO(5). General non-minimal cosets are discussed in [49].…”

Very light dilaton and naturally light Higgs boson

“…Consider a composite Higgs model based on the SU(2) gauge theory with N f Dirac fermions ψ i (i = 1, 2, · · · , N f ) of the fundamental representation [36,37] and with N s Dirac…”