Dynamics of Causal Fermion Systems. Field Equations and Correction Terms for a New Unified Physical Theory

TL;DR

This paper develops a formalism connecting causal fermion systems to field equations, deriving their dynamics, correction terms, and conservation laws, thus advancing a new unified physical theory with potential links to quantum collapse models.

Contribution

It introduces a formalism linking the causal action principle to fields on space-time, derives associated field equations, and analyzes correction terms and symmetries in causal fermion systems.

Findings

Derived field equations from the causal action principle.

Identified stochastic and non-linear correction terms.

Established a connection between symmetries and conservation laws.

Abstract

The theory of causal fermion systems is a new physical theory which aims to describe a fundamental level of physical reality. Its mathematical core is the causal action principle. In this thesis, we develop a formalism which connects the causal action principle to a suitable notion of fields on space-time. We derive field equations from the causal action principle and find that the dynamics induced by the field equations conserve a symplectic form which gives rise to an Hamiltonian time evolution if the causal fermion system admits a notion of time. In this way, we establish the dynamics of causal fermion systems. Remarkably, the causal action principle implies that there are correction terms to the field equations, which we subsequently derive and study. In particular, we prove that there is a stochastic and a non-linear correction term and investigate how they relate to the Hamiltonian time evolution. Furthermore, we give theorems which generalize the connection between symmetries and conservation laws in Noether's theorems to the theory of causal fermion systems. The appearance of the particular correction terms is reminiscent of dynamical collapse models in quantum theory.