Light composite Higgs boson from higher representations versus electroweak precision measurements: Predictions for CERN LHC

Abstract

We investigate theories in which the technifermions in higher dimensional representations of the technicolor gauge group dynamically break the electroweak symmetry of the standard model.Somewhat surprisingly, for the two-index symmetric representation of the gauge group the lowest number of techniflavors needed to render the underlying gauge theory quasi conformal is two. This is exactly one doublet of technifermions with respect to the weak interactions promoting these theories to ideal candidates of "walking" type technicolor models. From the point of view of the weak interactions the two techniflavor theory has a Witten anomaly, which we cure by introducing a fourth family of leptons. An elegant feature of this model is that the techniquarks * Electronic address: dietrich@nbi.dk † Electronic address: francesco.sannino@nbi.dk ‡ Electronic address: kimmo.tuominen@phys.jyu.fi

Gauge coupling unification via a technicolor model

“…We examine what happens to the running of the SM couplings when the Higgs sector is replaced by the MWT theory proposed and investigated in [4,5]. This model has technicolor group SU(2) with two techniflavors in the two-index symmetric representation of the technicolor group.…”

“…This approach consists in letting only one doublet of techniquarks transform non-trivially under the electroweak symmetries with the rest of the matter remaining in electroweak sin-glets, as suggested in [5] and later on used in [29]. In this case all techniquarks transform still under the technicolor gauge group and hence contribute to rendering the technicolor dynamics quasiconformal without affecting the leading perturbative contribution to the electroweak precision parameters.…”

“…Much progress has been made recently in developing new models of technicolor type able to address the old problems for technicolor [2,3,4,5,6]. We have even identified and carefully studied within these models possible dark matter particles in the form of technibaryons [7].…”

“…evolves very slowly [8,9,10,11,12]. The simplest of such models which passes the electroweak precision tests, requires the technicolor matter to transform according to the two index representation [39] of the technicolor gauge group [2,3,4,5]. In [18], the reader will find an exhaustive analysis of asymptotically free non-supersymmetric gauge theories with fermions in a given arbitrary higher dimensional representation of the SU(N) gauge group and their use to dynamically break the electroweak symmetry.…”

“…The minimal walking technicolor (MWT) model has been introduced in [4,5,7] and consists of a two technicolor gauge theory with technifermions in the two-index symmetric (i.e. adjoint) representation of the technicolor gauge group.…”