Structure of Dirac matrices and invariants for nonlinear Dirac equations

Abstract

We present invariants for nonlinear Dirac equations in space-time ${\mathbb R}^{n+1}$, by which we prove that a special choice of the Cauchy data yields free solutions. Our argument works for Klein-Gordon-Dirac equations with Yukawa coupling as well. Related problems on the structure of Dirac matrices are studied.