Numerical investigation of a recent radiation reaction model and comparison to the Landau-Lifschitz model

In Bild, Deckert, and Ruhl [Phys. Rev. D 99, 096001 (2019)2470-001010.1103/PhysRevD.99.096001] we presented an explicit and nonperturbative derivation of the classical radiation reaction force for a cutoff modeled by a special choice of tube of finite radius around the charge trajectories. In this paper, we provide a further, simpler, and so-called reduced radiation reaction model together with a systematic numerical comparison between both the respective radiation reaction forces and the one of Landau-Lifschitz as a reference. We explicitly construct the numerical flow for the new forces and present the numerical integrator used in the simulations, a Gauss-Legendre method adapted for delay equations. As comparison, we consider the cases of a constant electric field, a constant magnetic field, and a plane wave. In all these cases, the deviations between the three force laws are shown to be small. This excellent agreement is an argument for plausibility of both new equations but also means that an experimental differentiation remains hard. Furthermore, we discuss the effect of the tube radius on the trajectories, which turns out to be small in the regarded regimes. We conclude with a comparison of the numerical cost of the three corresponding integrators and argue that, numerically, the integrator of the reduced radiation reaction seems most efficient and the integrator of Landau-Lifschitz least efficient.