## Abstract

If supersymmetry is relevant at ordinary energies, the gravitino and possibly also the photino are relatively light particles. Observational constraints on these particles’ masses are reviewed. If the gravitino mass lies near the cosmological upper bound, ~ 1 keV, then gravitinos play an important role in galaxy formation.

## Keywords

Spin State Entropy Generation Vacuum Energy Grand Unify Theory Gravitino Mass
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## References

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- 19.The same line of reasoning would apply to any other stable neutral light particle with interactions much weaker than those of neutrinos.Google Scholar
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^{±}and Z (for which M ≈ 100 GeV and there are 9 spin states so n ≈ 9T^{3}) and used τ(T) M_{Pℓ}g_{I}(T)τ_{2}^{1}Tτ^{2}. Cf. the discussion of ν decoupling in S. Weinberg, Gravitation and Cosmology (Wiley, 1972), pp. 534-5. Keeping the factors of π, etc., increases the right hand side of (35), but this will not change g_{I}(Tg_{3/2}d) if, as expected in standard models, there are few if any new particle states between m_{Z}and ω_{T}. Note finally that the cross section for g_{3/2}+ f→γ_{1/2}+f (f = quark or lepton) corresponding to (15) is σ(g_{2/3}→γ_{1/2}) ≈ αs/F^{2}≈ αT^{2}/F^{2}, which would suffice to keep g_{3/2}in thermal equilibrium above T ≈ 16g_{I}(Tg_{3/2}d)_{2}^{1}GeV even if the threshold ω_{T}for R-hadrons were higher than this.Google Scholar

## Copyright information

© Plenum Press, New York 1983