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

TL;DR

This paper investigates the relationship between the goldstino superfield and superconformal symmetry breaking in low-scale SUSY models, analyzing constraints like X^2=0 and their validity in effective theories with multiple SUSY-breaking sources.

Contribution

It clarifies the connection between the goldstino superfield and the superconformal symmetry breaking superfield in low-scale SUSY models, extending the understanding to multiple SUSY-breaking sources.

Findings

The goldstino superfield is the infrared limit of the superconformal symmetry breaking superfield X.

Conditions are identified under which the X^2=0 constraint remains valid with additional SUSY-breaking fields.

The effective theory remains consistent with sgoldstino decoupling when certain conditions on the cutoff scale and sgoldstino mass are met.

Abstract

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. In the presence of additional fields that contribute to SUSY breaking we identify conditions for which X^2=0 remains valid, in the effective theory below a large but finite sgoldstino mass. The conditions ensure that the effective expansion (in 1/Lambda) of the initial Lagrangian is not in conflict with the decoupling limit of the sgoldstino (1/m_sgoldstino\sim Lambda/f, f<Lambda^2).