Rigid Poisson suspensions without roots

Abstract

Examples of rigid Poisson suspensions without roots are presented. The discrete rational component in spectrum of an ergodic automorphism S prevents some roots from existing. If S is tensorly multiplied by an ergodic automorphism of the space with a sigma-finite measure, discrete spectrum disappears in this product, but the memory of it can remain in the form of the absence of roots. In additional conditions, this effect is inherited by the Poisson suspension over the product.