Negative radiation pressure exerted on kinks

TL;DR

This paper demonstrates that in many scalar field models, kinks experience negative radiation pressure, being pulled towards radiation sources, a phenomenon confirmed by numerical and analytical methods, and shown to be robust.

Contribution

The study reveals the negative radiation pressure effect on kinks across various models, providing perturbative and analytical explanations, and confirming the effect's robustness.

Findings

Negative radiation pressure observed in φ^4 model

Zero average radiation pressure in sine-Gordon model

Kink acceleration follows Newton's law

Abstract

The interaction of a kink and a monochromatic plane wave in one dimensional scalar field theories is studied. It is shown that in a large class of models the radiation pressure exerted on the kink is negative, i.e. the kink is {\sl pulled} towards the source of the radiation. This effect has been observed by numerical simulations in the $\phi^4$ model, and it is explained by a perturbative calculation assuming that the amplitude of the incoming wave is small. Quite importantly the effect is shown to be robust against small perturbations of the $\phi^4$ model. In the sine-Gordon (sG) model the time averaged radiation pressure acting on the kink turns out to be zero. The results of the perturbative computations in the sG model are shown to be in full agreement with an analytical solution corresponding to the superposition of a sG kink with a cnoidal wave. It is also demonstrated that the acceleration of the kink satisfies Newton's law.