Gluino Search with Stop and Top in Nonuniversal Gaugino Mass Models at LHC and Future Colliders

Abstract

We discuss the gluino mass in the CMSSM and Nonuniversal Gaugino Mass Models (NUGM) frameworks in light of the results from the current LHC and Dark Matter experiments. We probe the gluino mass scales by considering its decay modes into stop and top quarks, $\tilde{g}\to {\tilde{t}}_{1}t$ and $\tilde{g}\to \bar{t}t{\tilde{\chi }}_1^0$, where ${\tilde{t}}_{1}t$ represents both ${\tilde{t}}_1\bar{t}$ and ${\tilde{t}}_1^{\ast }t$. The region with $m_{\tilde{g}}\lesssim 2$ TeV is excluded up to $68\%$ CL in the CMSSM if the gluino decays into a stop and top quark, while the $95\%$ CL exclusion requires $m_{\tilde{g}}\gtrsim 1.9$ TeV. Such exclusion bounds on the gluino mass more or less overlap with the current LHC results. The decay mode $\tilde{g}\to \bar{t}t{\tilde{\chi }}_1^0$ may take over if $\tilde{g}\to {\tilde{t}}_{1}t$ is not allowed. One can probe the gluino mass in this case up to about 1.5 TeV with $68\%$ CL in the CMSSM, and about 1.4 TeV with $95\%$ CL. A similar analyses in the NUGM framework yield exclusion curves for the gluino mass $m_{\tilde{g}}\gtrsim 2.1$ TeV at 14 TeV for both decay modes of the gluino under consideration. We also show that increasing the center of mass energy to 27 TeV can probe the gluino mass up to about 3 TeV through its decay mode into stop and top quark. The Dark Matter constraints are not very severe in the framework of NUGM, and they allow solutions with $m_{\tilde{g}},m_{\tilde{t}}\gtrsim 1$ TeV. In addition, with NUGM the LSP neutralino can coannihilate with gluino and/or stop for $m_{\tilde{g}},m_{\tilde{t}}\approx m_{{\tilde{\chi }}_1^0}\in [0.9-1.5]$ TeV. The 100 TeV FCC collider can probe the gluino masses up to about 6 TeV with $36.1f{b}^{-1}$ integrated luminosity. We also find that the decay $\tilde{g}\to \tilde{t}t$ can indirectly probe the stop mass up to about 4 TeV.