Electromagnetic mass-models in general relativity reexamined

TL;DR

This paper reexamines electromagnetic mass models in general relativity, proposing a new extended charged particle model with positive mass everywhere, achieved by unequal internal pressures and energy contributions from fields.

Contribution

It introduces a novel model where the particle's mass is positive throughout, using Einstein-Maxwell equations and effective density, differing from traditional negative mass models.

Findings

Mass is positive everywhere in the model.

Effective matter density is set to zero inside the particle.

The model satisfies Hawking and Ellis energy conditions.

Abstract

The problem of constructing a model of an extended charged particle within the context of general relativity has a long and distinguished history. The distinctive feature of these models is that, in some way or another, they require the presence of negative mass in order to maintain stability against Coulomb's repulsion. Typically, the particle contains a core of $negative$ mass surrounded by a positive-mass outer layer, which emerges from the Reissner-Nordstr\"{o}m field. In this work we show how the Einstein-Maxwell field equations can be used to construct an extended model where the mass is positive everywhere. This requires the principal pressures to be unequal inside the particle. The model is obtained by setting the "effective" matter density, rather than the rest matter density, equal to zero. The Schwarzschild mass of the particle arises from the electrical and gravitational field (Weyl tensor) energy. The model satisfies the energy conditions of Hawking and Ellis. A particular solution that illustrates the results is presented.