Top-BESS model and its phenomenology

Abstract

We introduce the top-BESS model which is the effective description of the strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector resonance. The model is a modification of the BESS model in the fermion sector. The triplet couples to the third generation of quarks only. This approach reflects a possible extraordinary role of the top quark in the mechanism of electroweak symmetry breaking. The low-energy limits on the model parameters found provide hope for finding sizable signals in the LHC Drell-Yan processes as well as in the s-channel production processes at the ILC. However, there are regions of the model parameter space where the interplay of the direct and indirect fermion couplings can hide the resonance peak in a scattering process even though the resonance exists and couples directly to top and bottom quarks.Comment: published in Physical Review D, minor changes in text, 21 pages, 37 figure

The limits on the strong Higgs sector parameters in the presence of new vector resonances

“…Similar interaction patterns can be found in various recent extensions of the SM, including the partial compositeness and extra-dimensional scenarios. As was shown in [34,35] this arrangement helps relax the tight restrictions placed by the electroweak precision data on the vector triplet coupling to the light SM fermions, the bottom quark included. While the study in this paper follows our tBESS model (and, in the relevant parts, matches the model considered in [31]), its conclusions will also be partly, or fully, applicable to a wider class of effective models, e.g., with different fermionic sectors.…”

“…Nevertheless, we would like to mention the example of the setup of this sector where only the third quark generation couples directly to the vector triplet and the interaction of the right top quark is disentangled from the interaction of the right bottom quark. We suggested and analyzed the effective model with this kind of the fermion sector in [34,35]. For the sake of completeness, we would like to point out that in this model the vector resonances do interact with the SM fermions, including the light ones, even if there are no direct interactions introduced.…”

“…The unitarity of our Lagrangian was investigated in detail in our previous publications [34,35]. Our analysis was based on the scattering amplitudes of the longitudinal EW gauge bosons to the EW gauge bosons.…”

“…The above-mentioned effective scenario has also been a basis for the effective Lagrangian we introduced and investigated in [34,35]. 1 Therein, the vector triplet couples directly to the third quark doublet only and to none of the other SM fermions.…”

“…Using the results of [31,34,35] we also analyze the treelevel unitarity limits of our model resulting from the scattering of the longitudinal EW gauge bosons for the allowed values of the Higgs couplings obtained in this work. When authors of [31] addressed unitarity questions the discovery of the Higgs boson was not confirmed yet.…”