Radiation reaction for multipole moments

TL;DR

This paper develops a Poincare-invariant framework for describing the effective dynamics of charged systems using intrinsic multipole moments, unifying particle and hydrodynamical approaches and analyzing radiation reaction effects.

Contribution

It introduces a relativistic-invariant definition of multipole moments and formulates a covariant action for fluids, linking particle and hydrodynamical models for radiation reaction analysis.

Findings

Established equivalence between particle and hydrodynamical approaches for charged dust.

Derived effective models for systems with dipole moments.

Proposed a covariant action functional for relativistic fluids.

Abstract

We propose a Poincare-invariant description for the effective dynamics of systems of charged particles by means of intrinsic multipole moments. To achieve this goal we study the effective dynamics of such systems within two frameworks -- the particle itself and hydrodynamical one. We give a relativistic-invariant definition for the intrinsic multipole moments both pointlike and extended relativistic objects. Within the hydrodynamical framework we suggest a covariant action functional for a perfect fluid with pressure. In the case of a relativistic charged dust we prove the equivalence of the particle approach to the hydrodynamical one to the problem of radiation reaction for multipoles. As the particular example of a general procedure we obtain the effective model for a neutral system of charged particles with dipole moment.