Global solutions to cubic Dirac and Dirac-Klein-Gordon systems on spacetimes close to the Minkowski space

TL;DR

This paper proves global existence and decay estimates for cubic Dirac and Dirac-Klein-Gordon systems on spacetimes close to Minkowski space, using advanced energy and vector field methods.

Contribution

It introduces a novel analysis of Dirac operators on curved backgrounds, handling their unique commutator structure and spacetime-dependent gamma matrices.

Findings

Established global existence for the systems.

Derived sharp pointwise decay estimates.

Handled the complex commutator structure of the Dirac operator.

Abstract

We establish global existence and derive sharp pointwise decay estimates of solutions to cubic Dirac and Dirac-Klein-Gordon systems on a curved background, close to the Minkowski spacetime. By squaring the Dirac operator, we reduce the analysis to a nonlinear wave-type equation involving spinorial connections, and apply energy estimates based on vector field methods and the hyperboloidal foliation framework, introduced by LeFloch-Ma. A key difficulty arises from the commutator structure of the Dirac operator, which exhibits significantly different behaviour from that of scalar field equations and requires refined control throughout the analysis, particularly due to the spacetime-dependent gamma matrices, which reduce to constant matrices in the flat Minkowski spacetime.