Quantizable Ghost-ridden theories using Kinetic Positivity Constraints

TL;DR

This paper introduces a method to make ghost-involving theories quantizable by imposing kinetic positivity constraints and Lorentz transformations, ensuring unitarity without removing ghosts, with applications in cosmology.

Contribution

The authors develop a novel approach to constrain ghost fields in theories, enabling quantization and physical consistency without eliminating ghosts.

Findings

The method ensures positivity of total kinetic energy in ghost theories.

It allows for effective Lagrangians with only physical degrees of freedom.

Applicable to cosmological models like quintom to maintain unitarity.

Abstract

We present a novel way to constrain the ghost field with respect to other physical fields present in a given theory such that the theory becomes quantizable. This is achieved by imposing positivity of the total kinetic energy of the system and performing Lorentz transformations in the field space manifold to arrive at an effective Lagrangian containing only physical degrees of freedom. Since models containing ghost fields such as quintom models are relevant in the cosmological context, this method can help ensure that such theories don't violate unitarity and can be treated as realistic candidates without the need to completely eliminate ghost(s).