Is quantum field theory a genuine quantum theory? Foundational insights on particles and strings

TL;DR

This paper questions whether quantum field theory aligns with orthodox quantum theory, proposing a reformulation based on particle currents that suggests particles are extended objects, potentially linking to string theory and offering new testable predictions.

Contribution

It introduces a non-orthodox reformulation of quantum theory using integral curves of particle currents, connecting quantum field phenomena with string theory concepts.

Findings

Measurable quantities in QFT are not described by hermitian operators.

A reformulation based on particle currents is proposed.

Particles may be extended objects, supporting string theory ideas.

Abstract

Practically measurable quantities resulting from quantum field theory are not described by hermitian operators, contradicting one of the cornerstone axioms of orthodox quantum theory. This could be a sign that some of the axioms of orthodox quantum theory should be reformulated. A non-orthodox reformulation of quantum theory based on integral curves of particle currents is advocated and possible measurable manifestations are discussed. The consistency with particle creation and destruction requires particles to be extended objects, which can be viewed as a new derivation of string theory. Within this reformulation, an indirect low-energy test of string theory is also possible.