Vertex operators for the superstring with manifest $d=6$ $\mathcal{N}=1$ supersymmetry

By extending the six-dimensional hybrid formalism for the superstring to include $d=6$ $\mathcal{N}=1$ superspace variables along with unconstrained bosonic ghost fields, we construct a manifestly spacetime supersymmetric vertex operator $U$. We demonstrate that the BRST invariance of $U$ implies the $d=6$ $\mathcal{N}=1$ SYM equations of motion in superspace. Furthermore, we show that spacetime supersymmetric scattering amplitudes can be computed in a manner analogous to that of the non-minimal pure spinor formalism.