Bispinor auxiliary fields in duality-invariant electrodynamics revisited

Motivated by recent progress in studying the duality-symmetric models of nonlinear electrodynamics, we revert to the auxiliary tensorial (bispinor) field formulation of the O(2) duality proposed by us in Ivanov and Zupnik [Nucl. Phys. B618, 3 ( 2001); Yad. Fiz. 67, 2212 ( 2004)]. In this approach, the entire information about the given duality-symmetric system is encoded in the O(2)-invariant interaction Lagrangian which is a function of the auxiliary fields V-alpha beta, (V) over bar ((alpha)over dot(beta)over dot). We extend this setting to duality-symmetric systems with higher derivatives and show that the recently employed "nonlinear twisted self-duality constraints'' amount to the equations of motion for the auxiliary tensorial fields in our approach. Some other related issues are briefly discussed and a few instructive examples are explicitly worked out. DOI: 10.1103/PhysRevD.87.065023