Quantum Field Theory with Null-Fronted Metrics

TL;DR

This paper explores quantum field theory in null-fronted metrics, revealing conditions under which particle number is conserved and highlighting challenges in interpreting quantization in more general cases.

Contribution

It analyzes the properties of null-fronted metrics in quantum field theory, identifying when particle conservation holds and discussing interpretational issues in more complex metrics.

Findings

Particle number is conserved in certain null-fronted metrics.

Quantization becomes ambiguous in more general null-fronted metrics.

The physical interpretation of the theory varies with metric complexity.

Abstract

There is a large class of classical null-fronted metrics in which a free scalar field has an infinite number of conservation laws. In particular, if the scalar field is quantized, the number of particles is conserved. However, with more general null-fronted metrics, field quantization cannot be interpreted in terms of particle creation and annihilation operators, and the physical meaning of the theory becomes obscure.