Ghost-free higher-derivative theory

TL;DR

This paper introduces a quantum system with higher derivatives in the Lagrangian that remains ghost-free, ensuring a bounded Hamiltonian spectrum and preserved unitarity, which is significant for theoretical physics.

Contribution

It provides a specific example of a higher-derivative quantum system that is free of ghosts, addressing a longstanding issue in such theories.

Findings

Hamiltonian spectrum is bounded from below

Unitarity is preserved in the system

Demonstrates a ghost-free higher-derivative quantum model

Abstract

We present an example of the quantum system with higher derivatives in the Lagrangian, which is ghost-free: the spectrum of the Hamiltonian is bounded from below and unitarity is preserved.