Unitarity in Infinite Derivative Theories

TL;DR

This paper demonstrates that infinite derivative scalar field theories can be unitary when formulated in Euclidean space and analytically continued to Minkowski space, ensuring consistent quantum behavior.

Contribution

It establishes a unitarity proof for infinite derivative scalar theories through Euclidean formulation and analytic continuation.

Findings

Theory is unitary in Euclidean space.

Unitarity maintained after analytic continuation to Minkowski space.

Provides a framework for consistent infinite derivative quantum field theories.

Abstract

In this paper, we consider an infinite derivative scalar field action with infinite derivative kinetic and interaction terms. We establish that the theory is unitary if the correlation functions are formulated in Euclidean space and then analytically continued in their external momenta to Minkowski space.