Causality as an emergent macroscopic phenomenon: The Lee-Wick O(N) model

TL;DR

This paper explores a Lee-Wick O(N) quantum model where causality emerges at macroscopic scales, demonstrating unitarity and Lorentz invariance in the large N limit, and discussing its acausal features.

Contribution

It introduces a Lee-Wick O(N) model showing emergent causality and unitarity at large N, addressing paradoxes in scattering.

Findings

The model has a unitary, Lorentz invariant S matrix at large N.

Causality emerges only at macroscopic scales, with some acausal properties discussed.

The theory is free of paradoxes in scattering experiments.

Abstract

In quantum mechanics the deterministic property of classical physics is an emergent phenomenon appropriate only on macroscopic scales. Lee and Wick introduced Lorentz invariant quantum theories where causality is an emergent phenomenon appropriate for macroscopic time scales. In this paper we analyze a Lee-Wick version of the O(N) model. We argue that in the large N limit this theory has a unitary and Lorentz invariant S matrix and is therefore free of paradoxes in scattering experiments. We discuss some of its acausal properties.