Low-scale SUSY breaking and the (s)goldstino physics

Understand

For a 4D N=1 supersymmetric model with a low SUSY breaking scale (f) and general Kahler potential K(Phi^i,Phi_j^*) and superpotential W(Phi^i) we study, in an effective theory approach, the relation of the goldstino superfield to the (Ferrara-Zumino) superconformal symmetry breaking chiral superfield X.

• In the presence of more sources of supersymmetry breaking, we verify the conjecture that the goldstino superfield is the (infrared) limit of X for zero-momentum and Lambda->\infty.
• (Lambda is the effective cut-off scale).
• We then study the constraint X^2=0, which in the one-field case is known to decouple a massive sgoldstino and thus provide an effective superfield description of the Akulov-Volkov action for the goldstino.