Vortex <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math> photon generation via spin-to-orbital angular momentum transfer in nonlinear Compton scattering
Mamutjan Ababekri, Ren-Tong Guo, Feng Wan, B. Qiao, Zhongpeng Li, Chong Lv, Bo Zhang, Weimin Zhou, Yuqiu Gu, Jianxing Li
Abstract
Vortex <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>γ</a:mi></a:math> photons with intrinsic orbital angular momenta possess a wealth of applications in various fields—e.g., strong-laser physics, nuclear physics, particle physics, and astrophysics—yet their generation remains unsettled. In this work, we investigate the generation of vortex <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>γ</c:mi></c:math> photons via nonlinear Compton scattering of ultrarelativistic electrons in a circularly polarized laser pulse. We develop a quantum electrodynamics scattering theory that explicitly addresses the multiphoton absorption and the angular momentum transfer mechanism. In pulsed laser fields, we unveil the vortex phase structure of the scattering matrix element, discuss how the vortex phase could be transferred to the radiated photon, and derive the radiation rate of the vortex <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>γ</e:mi></e:math> photon. We numerically examine the energy spectra and beam characteristics of the radiation, while also investigating the influence of finite laser pulses on the angular momentum and energy distribution of the emitted vortex <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>γ</g:mi></g:math> photons. Published by the American Physical Society 2024