b-tau Yukawa (Non-)Unification in the CMSSM

TL;DR

This paper investigates the ratio of tau to bottom Yukawa couplings at the GUT scale within the CMSSM, identifying a parameter region consistent with experimental data where the ratio approaches 3/2, especially in the large tan beta regime.

Contribution

It explores less fine-tuned parameter regions in the CMSSM where Yukawa unification is not exact, aligning with current experimental constraints.

Findings

The GUT scale y_tau/y_b ratio can be close to 3/2 in certain parameter regions.

A preferred parameter region is identified within the reach of the LHC.

Exact Yukawa unification is only possible for very specific parameters.

Abstract

Supersymmetric Grand Unification usually provides unification of the bottom quark and the tau lepton Yukawa couplings at the GUT scale. In the CMSSM this can be realised only for a very particular choice of parameters. In this letter we study the GUT scale ratio y_tau/y_b for less peculiar parameters in the large tan beta regime and identify one parameter region preferred by current experimental data. In this region, which is well within the reach of the LHC, the ratio is very close to the recently proposed value of 3/2.