Angular modulation of nonlinear Breit-Wheeler yield by vacuum dichroism

Vacuum polarization is numerically investigated for the interaction between a GeV electron beam and a counterpropagating ultraintense laser pulse in the quantum radiation dominated-regime (QRDR). We identify a signal of vacuum polarization in pair density using a straightforward one-stage setup, cir...

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Bibliographic Details
Published in:arXiv.org 2024-12
Main Authors: Jia-Ding, Chen, Ya-Nan Dai, Kai-Hong Zhuang, Jing-Jing, Jiang, Shen, Baifei, Yue-Yue, Chen
Format: Article
Language:English
Subjects:
Birefringence
Dichroism
Electron beams
Electron-positron pairs
Forward scattering
Lasers
Linear polarization
Particle decay
Photons
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Summary:Vacuum polarization is numerically investigated for the interaction between a GeV electron beam and a counterpropagating ultraintense laser pulse in the quantum radiation dominated-regime (QRDR). We identify a signal of vacuum polarization in pair density using a straightforward one-stage setup, circumventing the challenge of preparations of highly polarized probe photons or precise measurements of photon polarization. In our scheme, most electrons are scattered in the direction of laser propagation while emitting substantial linearly polarized gamma photons. These photons undergo vacuum birefringence and dichroism before decaying into electron-positron pairs via the nonlinear Breit-Wheeler process. We demonstrate that vacuum dichroism enhances the purity of linear polarization, which suppresses the overall yield of electron-positron pairs and allows energetic photons to penetrate deeper into the laser pulse. The pairs produced by these energetic photons are more likely to be deflected into small-angle regions rather than being reflected, leading to an enhancement of pair yield in forward scattering. The difference in positron yield may have potential applications in measuring vacuum polarization effect in future laser-particle experiments.
ISSN:2331-8422