Third family quasi-Yukawa unification: Higgsino dark matter, NLSP gluino and all that

TL;DR

This paper investigates third family quasi-Yukawa unification within a supersymmetric model, predicting specific sparticle spectra including Higgsino dark matter and NLSP gluino, with implications for collider and dark matter searches.

Contribution

It introduces a framework for third family QYU with soft symmetry breaking, predicting viable sparticle spectra and dark matter candidates, including Higgsino-like solutions, consistent with experimental constraints.

Findings

NLSP gluino with mass 1.3-2.5 TeV accessible at LHC Run 3

Stop-neutralino coannihilation solutions with heavy stops >1.8 TeV

Wino-like and Higgsino-like dark matter solutions compatible with relic density

Abstract

We explore the implications of third family ($t-b-\tau$) quasi-Yukawa unification (QYU) for collider and dark matter (DM) searches within the framework of a supersymmetric $SU(4)_c \times SU(2)_L \times SU(2)_R$ model. The deviation from exact Yukawa unification is quantified through the relation $y_t : y_b : y_\tau = |1+C|:|1-C|:|1+3C|$, with $C$ being a real parameter ($|C| \leq 0.2$). We allow for the breaking of left-right symmetry both by the soft scalar and gaugino mass parameters and obtain a variety of viable solutions that predict the sparticle mass spectrum including LSP DM (whose stability is guaranteed by a $Z_2$ gauge symmetry). We highlight solutions that include an NLSP gluino with mass $\sim$ 1.3-2.5 TeV, which should be accessible at LHC Run 3. There also exist NSLP stop solutions with masses heavier than about 1.8 TeV, which are consistent with the LSP neutralino dark matter relic density through stop-neutralino coannihilation. We identify A-resonance solutions with DM mass $\sim$ 0.8 - 2 TeV, as well as bino-chargino, bino-slepton and bino-stau co-annihilation scenarios. Finally, we also identify Wino-like ($\sim99\%$) and Higgsino-like ($\sim99\%$) solutions whose masses are heavier than about 1.5 TeV and 1 TeV, respectively. These solutions are compatible with the desired dark matter relic density and testable in ongoing and future direct detection experiments.