A 125 GeV scalar improves the low-energy data support for the top-BESS model

TL;DR

Adding a 125 GeV scalar to the top-BESS model enhances its compatibility with low-energy data, indicating a potential higher compositeness of the top quark compared to the bottom quark.

Contribution

This work introduces a scalar resonance into the top-BESS model, improving its fit to experimental data and providing new insights into the top quark's compositeness.

Findings

The scalar extension increases the model's statistical support.

Best-fit parameters suggest a more composite top quark.

The model remains consistent with low-energy phenomenology.

Abstract

We investigate how adding a scalar resonance of a mass 125 GeV affects the low-energy data support for the top-BESS model as well as its low-energy free parameter limits. The top-BESS model is an effective Lagrangian, a modification of the well-known BESS model, with an ambition to describe phenomenology of the lowest bound states of strongly-interacting theories beyond the Standard model. In particular, the SU(2)_{L+R} vector resonance triplet of hypothetical bound states is a centerpiece of BESS-like effective models. The top-BESS model assumes that the triplet couples directly to the third quark generation only. This assumption reflects a possible special standing of the third quark generation, and the top quark in particular, in physics of electroweak symmetry breaking. Our findings suggest that the 125 GeV scalar extension of the top-BESS model results in a higher statistical support for the model. The best-fit values of the model's free parameters are consistent with the top quark having a higher degree of compositeness than the bottom quark.