On a causal quantum stochastic double product integral related to Lévy area

We study the family of causal double product integrals Pi(a < x < y < b) (1 + i lambda/2 (dP(x)dQ(y) - dQ(x)dP(y)) + i mu/2 (dP(x)dP(y) + dQ(x)dQ(y))), where P and Q are the mutually nonco ...