Quantum field theory on a growing lattice

Abstract

We construct the classical and canonically quantized theories of a massless scalar field on a background lattice in which the number of points - and hence the number of modes - may grow in time. To obtain a well-defined theory certain restrictions must be imposed on the lattice. Growth-induced particle creation is studied in a two-dimensional example. The results suggest that local mode birth of this sort injects too much energy into the vacuum to be a viable model of cosmological mode birth. © SISSA/ISAS 2004.