A noncommutative sigma model

Abstract

We replace the classical string theory notions of mapping between parameter space and world-time with noncommutative tori mapping between these spaces. The dynamics of mappings between different noncommutative tori are studied and noncommutative versions of the Polyakov action and the Euler-Lagrange equations are derived. The quantum torus is studied in detail, as well as C*-homomorphisms between different quantum tori. A finite dimensional representation of the quantum torus is studied, and the partition function and other path integrals are calculated. At the end we prove existence theorems for mappings between different noncommutative tori.