Sparticle mass spectra from SU(5) SUSY GUT models with $b-\tau$ Yukawa coupling unification

TL;DR

This paper investigates SU(5) SUSY GUT models with b-tau Yukawa unification, analyzing parameter space and predicting sparticle masses, with implications for LHC detectability and dark matter compatibility.

Contribution

It provides a detailed analysis of the parameter space for SU(5) SUSY GUT models with b-tau Yukawa unification, including two solution classes and their phenomenological implications.

Findings

Low tanβ solutions have gluino masses 1-4 TeV, squark masses 1-5 TeV.

Large tanβ solutions occur at 35-60, with gluino masses 0.5-2 TeV.

Some solutions are beyond LHC reach, others are accessible, and dark matter compatibility is discussed.

Abstract

Supersymmetric grand unified models based on the gauge group SU(5) often require in addition to gauge coupling unification, the unification of b-quark and $\tau$-lepton Yukawa couplings. We examine SU(5) SUSY GUT parameter space under the condition of $b-\tau$ Yukawa coupling unification using 2-loop MSSM RGEs including full 1-loop threshold effects. The Yukawa-unified solutions break down into two classes. Solutions with low tan\beta ~3-11 are characterized by gluino mass ~1-4 TeV and squark mass ~1-5 TeV. Many of these solutions would be beyond LHC reach, although they contain a light Higgs scalar with mass <123 GeV and so may be excluded should the LHC Higgs hint persist. The second class of solutions occurs at large tan\beta ~35-60, and are a subset of $t-b-\tau$ unified solutions. Constraining only $b-\tau$ unification to ~5% favors a rather light gluino with mass ~0.5-2 TeV, which should ultimately be accessible to LHC searches. While our $b-\tau$ unified solutions can be consistent with a picture of neutralino-only cold dark matter, invoking additional moduli or Peccei-Quinn superfields can allow for all of our Yukawa-unified solutions to be consistent with the measured dark matter abundance.