Vacuum stability in stau-neutralino coannihilation in MSSM

Abstract

The 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.

On the coverage of neutralino dark matter in coannihilations at the upgraded LHC

“…We require our samples to satisfy the 2σ bounds of the Planck value of DM relic density [50] and the measured Higgs mass within the range of 125 ± 3 GeV [51]. In addition, we impose the vacuum stability constraints in stop and stau coannihilations, since the large mixing in stop and stau sector may lead to the charge or color breaking [52][53][54].…”

Hunting for scalar lepton partners at future electron colliders

“…Models where one of the smuons or staus is the next-to-LSP (NLSP) are of particular interest for dark matter model building in the MSSM because they offer a way to achieve the correct dark matter relic density, see, e.g., Refs. [36][37][38][39][40][41][42].…”

“…In the more well-studied case of stau coannihilation, the lightest stau is nearly degenerate in mass with the neutralino LSP and, thus, annihilation processes involving one or two staus in the initial state must also be accounted for in the calculation of the relic density [36][37][38]41,42]. While in constrained frameworks such as the CMSSM the observed relic density can only be obtained for stau masses below The luminosities referred to here are the integrated luminosities recorded in a specific polarization configuration.…”

Search for Supersymmetry with a Compressed Mass Spectrum in Events with a Soft τ Lepton, a Highly Energetic Jet, and Large Missing Transverse Momentum in Proton-Proton Collisions at s=13 Sirunyan1, Tumasyan2, Adam3 et al. 2020Phys. Rev. Lett.130100View full textAdd to dashboardCite

“…This Letter describes a search for the production of stau particles (τ), SUSY partners of the τ lepton, considering a mass difference (Δm) between theχ 0 1 andτ of ≤ 50 GeV. These scenarios are motivated by models includingτ-χ 0 1 CA [12][13][14][15][16][17][18][19], where the calculated relic DM density is consistent with that measured by the WMAP and Planck Collaborations [9,10]. The CA cross section is exponentially enhanced by small Δmðτ;χ 0 1 Þ.…”

“…2 left). This benchmark is motivated by: (i) LHC searches to date have no sensitivity in these SSM1 compressed spectrum scenarios; and (ii) SSM1 scenarios with Δmðτ;χ 0 1 Þ ¼ 25 GeV provide the right CA cross section to give a DM relic density consistent with experiment [12][13][14][15][16][17][18][19]. Figure 2 right shows the observed 95% C.L.…”