String theory origin of constrained multiplets

We study the non-linearly realized spontaneously broken supersymmetry of the (anti-)D3-brane action in type IIB string theory. The worldvolume fields are one vector A_μ, three complex scalars ϕⁱ and four 4d fermions λ⁰, λⁱ. These transform, in addition to the more familiar N=4 linear supersymmetry, also under 16 spontaneously broken, non-linearly realized supersymmetries. We argue that the worldvolume fields can be packaged into the following constrained 4d non-linear N=1 multiplets: four chiral multiplets S, Yⁱ that satisfy S² =SYⁱ =0 and contain the worldvolume fermions λ⁰ and λⁱ; and four chiral multiplets W_α, Hⁱ that satisfy SW_α=SD¯_α⋅H¯^ı¯=0  and contain the vector A_μ and the scalars ϕⁱ. We also discuss how placing an anti-D3-brane on top of intersecting O7-planes can lead to an orthogonal multiplet Φ that satisfies S(Φ−Φ¯)=0, which is particularly interesting for inflationary cosmology.