Composite Higgses with seesaw EWSB

Abstract

We introduce a new class of Composite Higgs models in which electroweak symmetry is broken by a seesaw-like mechanism. If a global symmetry is broken sequentially at different scales, two sets of pseudo-Goldstone bosons will arise, one set being typically heavier than the other. If two Composite Higgs doublets mix, then the mass-squared of the lighter state can be driven negative, and induce EWSB. We illustrate with the example $SO(6) \rightarrow SO(5) \rightarrow SO(4)$, and derive an estimate of the light Higgs potential. We find that the introduction of an extra scale can ease many of the tensions present in conventional Composite Higgs models, especially those related to fine-tuning. In particular we find that we can significantly raise the upper bound on the mass of the elusive top partners.Comment: 19 pages, 2 figures. v2: JHEP version, mistake corrected, discussion on tuning and top-partners extende

See-saw composite Higgs model at the LHC: Linking naturalness to the 750 GeV diphoton resonance

“…Here we show how this can be achieved in the context of composite Higgs [3], based on the model proposed by some of the authors [4], with the Higgs and the new resonance realized as pseudo-Goldstone bosons of spontaneously broken global symmetries. This mechanism protects the scalar potential from the problematic UV sensitivity, and at the same time opens a door to address key open questions in the SM, such as the nature of dark matter (DM) and the origin of the matter-antimatter asymmetry in the Universe.…”

“…In [4] an elegant solution to the above problem was proposed, in the form of a see-saw type of EWSB, based on a sequential symmetry breaking pattern such as SOð6Þ → SOð5Þ → SOð4Þ, which gives rise to a pseudoGoldstone doublet ϕ and singlet η from the first breaking, and another doublet θ from the second breaking. Due to the sequential pattern, the η, ϕ fields are expected to be significantly heavier than θ, since SOð6Þ=SOð5Þ breaking interactions would generate a mass for η, ϕ but not θ.…”

“…Let us now discuss the main features of our setup (for a more detailed discussion, see [4]). The model features a global SOð6Þ symmetry that is spontaneously broken via SOð6Þ → SOð5Þ → SOð4Þ.…”

“…F 1 ¼ F 2 ), we also allow for the possibility that the two sets of Goldstone bosons have different decay constants (F 1 >F 2 ). As discussed in [4],a large hierarchy between the two scales F 1 ≫ F 2 will however reintroduce some degree of tuning.…”

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

“…(For earlier attempts using supersymmetry, see [15,16]. Alternative avenues being explored are found in [17][18][19]. )…”