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 $m \ll H$. 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 $m \gtrsim 10^4 \GeV$, and very small couplings (e.g. $h \lesssim 10^{-6}$ for $m \lesssim 10^8 \GeV$).