Top-bottom-tau Yukawa coupling unification in the MSSM+1VF and fermion masses as IR fixed points

TL;DR

This paper explores how extending the MSSM with a vectorlike family allows for precise unification of top, bottom, and tau Yukawa couplings at an IR fixed point, with implications for new physics scales.

Contribution

It demonstrates that Yukawa coupling unification is achievable in MSSM+1VF with large unified couplings, predicting new physics at 3-30 TeV and linking to IR fixed points.

Findings

Yukawa unification is possible with large unified couplings.

Preferred new physics scale is between 3 and 30 TeV.

Compatibility with Higgs boson mass constraints.

Abstract

In the MSSM extended by a complete vectorlike family, precise top, bottom and tau Yukawa coupling unification can be achieved assuming SUSY threshold corrections which are typical for comparable superpartner masses. Furthermore, the unification is possible with a large unified coupling, implying that all three fermion masses can be simultaneously close to their IR fixed points. Assuming unified Yukawa couplings of order one or larger, the preferred common scale of new physics (superpartners and vectorlike matter) is in the 3 TeV to 30 TeV range, with larger couplings favoring smaller scales. Splitting superpartner masses from masses of vectorlike fields, the preferred scales extend in both directions. The multi-TeV scale for superpartners is compatible with and independently suggested by the Higgs boson mass.