Road map through the desert with scalars

In the context of the gauge coupling unification, we present a comprehensive analysis of the extensions of the Standard Model with vector-like fermions and scalars. We find 145 models that satisfy the unification condition, which are distinguishable by the number of new particles in the spectrum and by their transformation properties under the gauge symmetry group of the Standard Model. For all models we derive lower bounds on the exotic fermion and scalar masses, stemming from the measurement of the strong gauge coupling scale dependence, from the heavy stable charged particle searches, and from the electroweak precision tests. We also discuss the potential of testing the unification scenarios at the future 100 TeV collider and in the proton decay experiments. We show that many models can already be excluded based on the current data, while many others will be entirely probed in the coming years.

Automated summary

In this study, we comprehensively analyze the extensions of the Standard Model with vector-like fermions and scalars in the context of gauge coupling unification. We identify 145 models that satisfy the unification condition, distinguishable by the number of new particles in the spectrum and their transformation properties under the gauge symmetry group. Lower bounds on the exotic fermion and scalar masses are derived for all models based on measurements of the strong gauge coupling scale dependence, searches for heavy stable charged particles, and electroweak precision tests. The potential of testing these unification scenarios at future colliders and proton decay experiments is also discussed, with some models already excluded based on current data while others will be probed in the years to come.