Vector-Like Strong Coupling Theory with Small S and T Parameters

Maekawa, Nobuhiro

doi:10.1143/ptp/93.5.919

Cited by 12 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where the T parameter is proportional to the mass splitting between the charged Higgs and the CP-odd neutral one in the doublet, and is therefore small (smaller than the contribution of the Higgs). The last contribution can be approximate by the contribution of loops of techni-fermions (thus diagrammatically close to the contribution of the spin-1 resonances), and reads [12,50] ∆S…”

Section: Bounds From the Higgs Couplings And Ewptsmentioning

confidence: 90%

Fundamental composite 2HDM: SU(N) with 4 flavours

Cacciapaglia

2016

J. High Energ. Phys.

102

145

View full text Add to dashboard Cite

We present a new model of composite Higgs based on a gauged SU(N) group with 4 Dirac fermions in the fundamental representation. At low energy, the model has a global symmetry SU(4)×SU(4) broken to the diagonal SU(4), containing 2 Higgs doublets in the coset. We study in detail the generation of the top mass via 4-fermion interactions, and the issue of the vacuum alignment. In particular, we prove that, without loss of generality, the vacuum can always be aligned with one doublet. Under certain conditions on the top pre-Yukawas, the second doublet, together with the additional triplets, is stable and can thus play the role of Dark Matter. This model can therefore be an example of composite inert-2HDM model.

show abstract

Section: Bounds From the Higgs Couplings And Ewptsmentioning

confidence: 90%

Fundamental composite 2HDM: SU(N) with 4 flavours

Cacciapaglia

2016

J. High Energ. Phys.

102

145

View full text Add to dashboard Cite

show abstract

“…In Fig. 6 we illustrate this behavior by computing S and T , following [46] and performing the EWPT fit for m h = 125 GeV [47]. In the left panel, we indicate with a green shaded area the 95%CL EWPT exclusion region in the (m L2 , x n ) plane.…”

Section: Collider Signals and Electroweak Constraintsmentioning

confidence: 91%

2:1 for Naturalness at the LHC?

Arkani-Hamed,

Blum,

D'Agnolo

et al. 2012

Preprint

113

View full text Add to dashboard Cite

A large enhancement of a factor of 1.5 -2 in Higgs production and decay in the diphoton channel, with little deviation in the ZZ channel, can only plausibly arise from a loop of new charged particles with large couplings to the Higgs. We show that, allowing only new fermions with marginal interactions at the weak scale, the required Yukawa couplings for a factor of 2 enhancement are so large that the Higgs quartic coupling is pushed to large negative values in the UV, triggering an unacceptable vacuum instability far beneath the 10 TeV scale. An enhancement by a factor of 1.5 can be accommodated if the charged particles are lighter than 150 GeV, within reach of discovery in almost all cases in the 8 TeV run at the LHC, and in even the most difficult cases at 14 TeV. Thus if the diphoton enhancement survives further scrutiny, and no charged particles beneath 150 GeV are found, there must be new bosons far beneath the 10 TeV scale. This would unambiguously rule out a large class of fine-tuned theories for physics beyond the Standard Model, including split SUSY and many of its variants, and provide strong circumstantial evidence for a natural theory of electroweak symmetry breaking at the TeV scale. Alternately, theories with only a single fine-tuned Higgs and new fermions at the weak scale, with no additional scalars or gauge bosons up to a cutoff much larger than the 10 TeV scale, unambiguously predict that the hints for a large diphoton enhancement in the current data will disappear.

show abstract

“…Luty and Sundrum [255] constructed models in which the PNGB's give negative contributions to S. To obtain ∆S ≃ −0.1 from this source, one needs technifermions with j L = 2 and PNGB's with masses of order 200 GeV. More generally, other models may include arbitrary numbers of vectorlike pairs of electroweak charged particles [256] (e.g., both a left-handed and right-handed gauged doublet with j − = 0 and a Dirac mass coming from other external dynamics) with no cost in S. The Top-Seesaw model (Section 4.4) contains additional vectorlike fermions, allowing both S and T to be completely consistent with present data. Likewise, the Kaluzsa-Klein recurrences of ordinary quarks and leptons in extra-dimensional models are vectorlike pairs, and are largely unconstrained by S. These examples are discussed in Section 4.6.…”

Section: Oblique Radiative Correctionsmentioning

confidence: 99%