Vacuum stability in stau-neutralino coannihilation in MSSM

Publication date: Available online 3 December 2018Source: Physics Letters BAuthor(s): Guang Hua Duan, Chengcheng Han, Bo Peng, Lei Wu, Jin Min YangAbstractThe stau-neutralino coannihilation provides a feasible way to accommodate the observed cosmological dark matter (DM) relic density in the minimal supersymmetric standard model (MSSM). In such a coannihilation mechanism the stau mass usually has an upper bound since its annihilation rate becomes small with the increase of DM mass. Inspired by this observation, we examine the upper limit of stau mass in the parameter space with a large mixing of staus. We find that the stau pair may dominantly annihilate into dibosons and hence the upper bound on the stau mass (∼400 GeV) obtained from the ff¯ final states can be relaxed. Imposing the DM relic density constraint and requiring a long lifetime of the present vacuum, we find that the lighter stau mass can be as heavy as about 1.4 TeV for the stau maximum mixing. However, if requiring the present vacuum to survive during the thermal history of the universe, this mass limit will reduce to about 0.9 TeV. We also discuss the complementarity of vacuum stability and direct detections in probing this stau coannihilation scenario.

Source: Physics Letters B - December 4, 2018 Category: Physics Source Type: research