LHC phenomenology of SO(10) models with Yukawa unification

Abstract

In this paper we study an SO(10) SUSY GUT with Yukawa unification for the third generation. We perform a global ${\ensuremath{\chi}}^{2}$ analysis given to obtain the GUT boundary conditions consistent with 11 low-energy observables, including the top, bottom and tau masses. We assume a universal mass, ${m}_{16}$, for squarks and sleptons and a universal gaugino mass, ${M}_{1/2}$. We then analyze the phenomenological consequences for the LHC for 15 benchmark models with fixed ${m}_{16}=20\text{ }\text{ }\mathrm{TeV}$ and with varying values of the gluino mass. The goal of the present work is to (i) evaluate the lower bound on the gluino mass in our model coming from the most recent published data of CMS and (ii) to compare this bound with similar bounds obtained by CMS using simplified models. The bottom line is that the bounds coming from the same-sign dilepton analysis are comparable for our model and the simplified model studied assuming $\mathcal{B}(\stackrel{\texttildelow{}}{g}\ensuremath{\rightarrow}t\overline{t}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{0})=100%$. However the bounds coming from the purely hadronic analyses for our model are 10%--20% lower than obtained for the simplified models. This is due to the fact that for our models the branching ratio for the decay $\stackrel{\texttildelow{}}{g}\ensuremath{\rightarrow}g{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1,2}^{0}$ is significant. Thus there are significantly fewer b-jets. We find a lower bound on the gluino mass in our models with ${M}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\gtrsim}1000\text{ }\text{ }\mathrm{GeV}$. Finally, there is a theoretical upper bound on the gluino mass which increases with the value of ${m}_{16}$. For ${m}_{16}\ensuremath{\le}30\text{ }\text{ }\mathrm{TeV}$, the gluino mass satisfies ${M}_{\stackrel{\texttildelow{}}{g}}\ensuremath{\le}2.8\text{ }\text{ }\mathrm{TeV}$ at 90% C.L. Thus, unless we further increase the amount of fine-tuning, we expect gluinos to be discovered at LHC 14.