Stochastic Analysis of an Accelerated Charged Particle -Transverse Fluctuations-

TL;DR

This paper investigates the stochastic transverse fluctuations of an accelerated charged particle, demonstrating partial cancellation of Unruh radiation through interference effects, challenging previous predictions of additional radiation emissions.

Contribution

It provides a detailed analysis of transverse momentum fluctuations and proves the equipartition theorem in the context of an accelerated particle interacting with a scalar field, revealing interference effects.

Findings

Unruh radiation is partially canceled by interference effects.

The stochastic motion of the particle follows the equipartition theorem.

No additional radiation remains after thermalization in the scalar-field model.

Abstract

An accelerated particle sees the Minkowski vacuum as thermally excited, and the particle moves stochastically due to an interaction with the thermal bath. This interaction fluctuates the particle's transverse momenta like the Brownian motion in a heat bath. Because of this fluctuating motion, it has been discussed that the accelerated charged particle emits extra radiation (the Unruh radiation) in addition to the classical Larmor radiation, and experiments are under planning to detect such radiation by using ultrahigh intensity lasers constructed in near future. There are, however, counterarguments that the radiation is canceled by an interference effect between the vacuum fluctuation and the fluctuating motion. In fact, in the case of an internal detector where the Heisenberg equation of motion can be solved exactly, there is no additional radiation after the thermalization is completed. In this paper, we revisit the issue in the case of an accelerated charged particle in the scalar-field analog of QED. We prove the equipartition theorem of transverse momenta by investigating a stochastic motion of the particle, and show that the Unruh radiation is partially canceled by an interference effect.