Constraining the Curvaton Scenario

We analyse the curvaton scenario in the context of supersymmetry. Supersymmetric theories contain many scalars, and therefore many curvaton candidates. To obtain a scale invariant perturbation spectrum, the curvaton mass should be small during inflation m ≪ H . This can be achieved by invoking symmetries, which suppress the soft masses and non-renormalizable terms in the potential. Other model-independent constraints on the curvaton model come from nucleosynthesis, gravitino overproduction, and thermal damping. The curvaton can work for masses m > ∼ 10 4 GeV, and very small couplings (e.g. h < ∼ 10 −6 for m < ∼ 10 8 GeV).