Novel aspects of radiation reaction in the classical and the quantum regime

Norman Neitz,Christoph H Keitel,Naveen Kumar,Felix Mackenroth,Karen Z Hatsagortsyan,Antonino Di Piazza

doi:10.1088/1742-6596/497/1/012015

Norman Neitz, Christoph H Keitel + Show 4 more

Open Access

https://doi.org/10.1088/1742-6596/497/1/012015

Copy DOI

Abstract

This work is dedicated to the study of radiation reaction signatures in the framework of classical and quantum electrodynamics. Since there has been no distinct experimental validation of radiation reaction and its underlying equations so far and its impact is expected to be substantial for the construction of new experimental devices, e.g., quantum x-free electron lasers, a profound understanding of radiation reaction effects is of special interest. Here, we describe how the inclusion of quantum radiation reaction effects changes the dynamics of ultra-relativistic electron beams colliding with intense laser pulses significantly. Thereafter, the angular distribution of emitted radiation is demonstrated to be strongly altered in the quantum framework, if in addition to single photon emission also higher order photon emissions are considered. Furthermore, stimulated Raman scattering of an ultra-intense laser pulse in plasmas is examined and forward Raman scattering is found to be significantly increased by the inclusion of radiation reaction effects in the classical regime. The numerical simulations in this work show the feasibility of an experimental verification of the predicted effects with presently available lasers and electron accelerators.

Highlights

If a charged particle, an electron for definiteness, is exposed to an electromagnetic background field, it will be accelerated and subsequently emit radiation. This process is fundamental in electrodynamics, the usual classical treatment is insufficient, since it does not take into account radiation reaction (RR), i.e., the back reaction of the emitted radiation on the charged particle itself [1, 2]
RR effects are of pure theoretical interest, as even in the framework of classical electrodynamics theoretical methods such as renormalization are necessary to describe the self-coupled dynamics [7]. It has been reported, that the so-called Landau-Lifshitz (LL) equation is in theory the accurate equation of motion for an electron of mass m and charge e < 0 in the framework of classical electrodynamics [1, 2, 7, 8, 9, 10, 11]. (Units with = c = 1 are used.) In case of an electromagnetic plane wave the LL equation allows for an analytical solution [12] and it was demonstrated that if the parameter Rc = αχ0ξ0 is of order of unity, the dynamics of an electron with initial momentum pμi colliding with a plane wave laser field is significantly altered by RR effects
In contrast to the classically predicted narrowing of the energy width of particle beams, we have shown by employing a kinetic approach that the stochastic nature of photon emission spreads up the energy distribution of the electrons, if quantum effects are substantial

Summary

Introduction

An electron for definiteness, is exposed to an electromagnetic background field, it will be accelerated and subsequently emit radiation. We describe how the inclusion of quantum radiation reaction effects changes the dynamics of ultra-relativistic electron beams colliding with intense laser pulses significantly. 2. Kinetic approach to quantum radiation reaction we investigate RR effects in the collision of an intense laser pulse with an ultra-relativistic electron beam.

Results

Conclusion