Renormalizable Quantum Gravity in Low Energy without Violating Unitarity

TL;DR

This paper proposes a novel approach to quantum gravity that maintains unitarity through ghost particle constraints, enabling a renormalizable theory that can address the cosmological constant problem.

Contribution

It introduces techniques involving ghost particles and zero-norm states to preserve unitarity and achieve renormalizability in quantum gravity without violating physical principles.

Findings

Ghost mass scale influences quantum effects and cosmological constant.

Higher-derivative propagators suppress divergences in quantum gravity.

Inclusion of ghost partners makes matter-coupled quantum gravity renormalizable.

Abstract

We introduce new techniques that can preserve unitarity of the system including ghost particles. Negative norms of the particles can be involved in zero-norm states by constraints of the physical space. These are useful to apply the higher-derivative propagator for quantum gravity to suppress divergences of vacuum energy and graviton mass correction. The quantum effects are mainly depending on the ghost mass scale. As the scale can be chosen in any order, the observed cosmological constant is realized. Further, applying ghost partners for the standard model particles, quantum gravity with matter fields becomes renormalizable with power counting arguments.