The role of scalar and pseudoscalar fields in determining nucleosynthesis bounds on the scale of supersymmetry breaking

The effect of spin-0 goldstino superpartners is considered on the nucleosynthesis bounds arising when a superlight gravitino appears as an effective massless neutrino species. When the scalar and pseudoscalar superpartners are relativistic they will decouple at much later times than the goldstino and consequently will be the dominant effect when obtaining a nucleosynthesis bound on the scale of supersymmetry breaking. Assuming that the scalar and pseudoscalar fields decouple at a temperature no later than O(100) MeV, then typically the scale of supersymmetry breaking F≳60 TeV. This corresponds to a lower bound on the gravitino mass m3/2≳1 eV.