Abstract

AbstractWe investigate the LHC sensitivity to supersymmetric models with light higgsinos, small R-parity breaking and gravitino dark matter. The limits on decaying gravitino dark matter from gamma-ray searches with the Fermi-LAT put a lower bound on the higgsino-like neutralino NLSP decay length, giving rise to a displaced-vertex collider signature. Using publicly available tools for simulation of signal, background and detector response, we find that higgsinos with masses of 100 – 400 GeV and R-parity violation ofζ~ 10−8– 10−9can show up in the 8 TeV LHC data with 10 – 30 fb−1of integrated luminosity. We demonstrate that in the case of a signal, the higgsino mass can be determined by reconstruction of the dimuon mass edge.

Highlights

  • The SM processes that dominate the dimuon channel are: γ∗/Z∗ → μ+μ− tt V ∗V ∗, where V = W, Z.we give the next-to-leading order (NLO) cross section for the processes that we have simulated for our study

  • We will discuss why the signal we consider would hide from the LHC searches performed so far, and show that the search strategy that we propose here could reveal new physics already in the data accumulated during the LHC runs with proton collisions at 8 TeV center-of-mass energy

  • Since right-handed neutrinos are created from B−L Higgs decays, this scenario allows for gravitino dark matter, leptogenesis and the correct values for the neutrino mass parameters while requiring lower reheating temperatures compared to the thermal leptogenesis case

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Summary

Decaying dark matter in the light-higgsino scenario

If we abandon the requirement of R-parity, the additional terms in the MSSM superpotential together with the soft terms introduce 99 new free parameters into the model [29]. By allowing only for the bilinear terms, baryon number is conserved, and the number of new parameters is reduced to 9 [29, 30]) Such a scenario can be realised through the spontaneous breaking of B − L, the difference between baryon and lepton number [19].

Bilinear R-parity breaking
Gravitino and neutralino decays
Cosmological bounds
Big bang nucleosynthesis
Gravitino dark matter mass
Fermi-LAT bound on the gravitino lifetime
Higgsino production and decay at the LHC
Signatures and search strategy
Benchmark points
Background
Tools and settings
Mass determination
Result
Conclusion
Findings
A Higgsino and gravitino branching ratios
Full Text
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