Problems with models of a fundamental length

TL;DR

This paper critically analyzes models proposing a fundamental minimal length, highlighting their violations of causality and unitarity at the propagator level.

Contribution

It identifies fundamental issues in ad hoc models of minimal length, emphasizing their inconsistencies with core physical principles.

Findings

Models violate causality

Models violate unitarity

Highlights need for consistent theories of minimal length

Abstract

I critically examine various ad hoc models describing a fundamental minimal length at the level of the propagator. They violate causality and/or unitarity.