Triality Invariance in the N=2 Superstring

Understand

We prove the discrete triality invariance of the N=2 NSR superstring moving in a D=2+2 target space.

• We find that triality holds also in the Siegel-Berkovits formulation of the selfdual superstring.
• A supersymmetric generalization of Cayley's hyperdeterminant, based on a quartic invariant of the SL(2|1)^3 superalgebra, is presented.