Yukawa Unification Predictions for the LHC

TL;DR

This paper explores the implications of gauge and third family Yukawa coupling unification at the GUT scale for the LHC, predicting observable superpartner masses and analyzing a comprehensive three-family model within the MSSM framework.

Contribution

It provides a detailed global chi^2 analysis of Yukawa unification effects on LHC phenomenology, including constraints on gluino, stop, and sbottom masses, and compares third family and full three-family models.

Findings

Gluino mass upper bound around 2 TeV, accessible at 14 TeV LHC.

Gluino decay branching ratios are diverse, not fitting simplified models.

Light charginos and neutralinos with bino-like LSP are possible.

Abstract

This paper is divided into two parts. In the first part we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the GUT scale. We perform a global chi^2 analysis including the observables M_W, M_Z, G_F, 1/alpha_em, alpha_s(M_Z), M_t,m_b(m_b), M_tau, BR(B -> X_s gamma), BR(B_s -> mu^+ mu^-) and M_h. The fit is performed in the MSSM in terms of 9 GUT scale parameters, while tan beta and mu are fixed at the weak scale. Good fits suggest an upper bound on the gluino mass, M_gluino \lesssim 2 TeV. This constraint comes predominantly from fitting the bottom quark and Higgs masses (assuming a 125 GeV Higgs). Gluinos should be visible at the LHC in the 14 TeV run but they cannot be described by the typical simplified models. This is because the branching ratios for gluino -> t tbar neutralino, b bbar neutralino, t bbar chargino^-, b tbar chargino^+, g neutralino are comparable. Stops and sbottoms may also be visible. Charginos and neutralinos can be light with the LSP predominantly bino-like. In the second part of the paper we analyze a complete three family model and discuss the quality of the global chi^2 fits and the differences between the third family analysis and the full three family analysis for overlapping observables. We note that the light Higgs in our model couples to matter like the Standard Model Higgs. Any deviation from this would rule out this model.