Field space geometry and nonlinear supersymmetry

We propose a geometric formulation of effective field theories via nonlinear supersymmetry. Nonsupersymmetric particles are embedded in constrained superfields governed by a nonlinear <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>σ</a:mi></a:math> model, and operators are collected into potentials on the target space. The use of chiral superfields standardizes the treatment of flavor across scalars and fermions, and the minimal jet bundle extension makes invariance under derivative field redefinitions manifest.