Light composite scalar boson from a see-saw mechanism in two-scale TC models

Abstract

We consider the possibility of a light composite scalar boson arising from mass mixing between a relatively light and heavy scalar singlets in a see-saw mechanism expected to occur in two-scale Technicolor (TC) models. A light composite scalar boson can be generated when the TC theory features two technifermions species in different representations, R 1 and R 2 , under a single technicolor gauge group, with characteristic scales Λ 1 and Λ 2 . We determine the final composite scalar fields, Φ 1 and Φ 2 , effective theory using the effective potential for composite operators approach. To generate a light composite scalar it is enough to have a walking (or quasi-conformal) behavior just for one of the technifermions representations.The nature of the electroweak symmetry breaking is one of the most important problems in particle physics, and the 125 GeV new resonance discovered at the LHC [1] has many of the characteristics expected for the Standard Model (SM) Higgs boson. If this particle is a composite or an elementary scalar boson is still an open question. Many models have considered the possibility of a light composite Higgs based on effective Higgs potentials as reviewed in Ref.[2]. The reason for the existence of the different models (or different potentials) for a composite Higgs, is a consequence of our poor knowledge of the strongly interacting theories, that is reflected in the many choices of parameters in the effective potentials. On the other hand the composite scalar boson mass can be calculated based on the dynamics of the theory [3], and this approach, although more complex, is more restrictive than the analysis of potential coefficients in

The extreme walking behavior in a 331-TC model

“…We emphasize that the seesaw mechanism expected to occur in this model is not exactly the same one as described in Ref. [42]; in the model proposed the extreme walking behavior displayed by exotic techniquarks is due to their strong U (1) X interaction and in this case in Eq. (1), μ ≈ 2 = 331 and 2 , it is not generated by the TC sector.…”

“…In the Refs. [14][15][16]25] we discussed the possibility of obtaining a light composite TC scalar boson, this result is a direct consequence of extreme walking (or quasi-conformal) technicolor theories, where the asymptotic self-energy behavior is described by Eq. ( 1).…”

“…The exotic technifermions have two different energy scales and the 331-TC model corresponds to an example of two-scale Technicolor (TC) model, in the Ref. [16] we considered the possibility of a light TC composite boson arising from mass mixing between a relatively light and heavy composite scalar singlets from a see-saw mechanism expected to occur in two-scale TC model. We emphasize that the see-saw mechanism expected to occur in this model is not exactly the same one described in the Ref [16], in the model proposed the extreme walking behavior displayed by exotic techniquarks is due to their strong U(1) X interaction and in this case in Eq.…”

“…In the Ref. [16] we considered the possibility of a light composite scalar boson arising from mass mixing between a relatively light and heavy scalar singlets from a see-saw mechanism expected to occur in two-scale Technicolor (TC) models and we identified that, regardless of the approach used for generating a light composite scalar boson, the behavior exhibited by extreme walking technicolor theories, is the main feature needed to produce a light composite scalar boson compatible with the boson observed at the LHC.…”

Schwinger–Dyson approach and its application to generate a light composite scalar

“…The coefficients, λ R i 4n , λ R i 6n to i = 1, 2, shown in equation above are described in Ref. [68]. The most important characteristic of this effective Lagrangian is the mixing term…”