arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1805.02027hep-phphysics.atom-phphysics.plasm-ph
收藏

强Laser场中辐射电子的极化理论

Theory of Radiative Electron Polarization in Strong Laser Fields

D. Seipt, D. Del Sorbo, C. P. Ridgers, A. G. R. Thomas

摘要:

通过Sokolov-Ternov效应的电子和正电子的辐射极化对于高能物理中的应用是重要的。辐射自旋极化是量子辐射反应影响电子自旋动力学的一种表现。我们最近提出,类似的Sokolov-Ternov效应可能发生在超高强度激光的强电磁场中,这将导致飞秒内自旋极化的积累。本文提出了一种描述强电磁场中光束偏振的密度矩阵形式。首先,我们使用密度矩阵的形式主义研究自旋翻转的非线性康普顿散射及其依赖于初始极化状态的电子。数值计算表明,径向极化的散射电子束在圆偏振激光,我们发现方位角的偏振模式的超短激光脉冲。仅发射一个光子就可以获得接近9%的偏振度。我们发展的理论推导出一个局部常数交叉场近似(LCFA)的极化密度矩阵,这是一个推广的著名的LCFA散射率。我们发现自旋相关的表达式,可以包括在电磁带电粒子模拟代码,如粒子在细胞等离子体模拟代码,使用蒙特卡罗模块。特别是,这些表达式包括自旋翻转率为任意初始极化的电子。通过与超短激光脉冲中电子极化的精确QED计算的明确比较,证实了LCFA的有效性。

英文摘要:

Radiative polarization of electrons and positrons through the Sokolov-Ternov effect is important for applications in high-energy physics. Radiative spin-polarization is a manifestation of quantum radiation reaction affecting the spin-dynamics of electrons. We recently proposed that an analogue of the Sokolov-Ternov effect could occur in the strong electromagnetic fields of ultra-high-intensity lasers, which would result in a build-up of spin-polarization in femtoseconds. In this paper we develop a density matrix formalism for describing beam polarization in strong electromagnetic fields. We start by using the density matrix formalism to study spin-flips in non-linear Compton scattering and its dependence on the initial polarization state of the electrons. Numerical calculations show a radial polarization of the scattered electron beam in a circularly polarized laser, and we find azimuthal asymmetries in the polarization patterns for ultra-short laser pulses. A degree of polarization approaching 9 % is achieved after emitting just a single photon. We develop the theory by deriving a local constant crossed field approximation (LCFA) for the polarization density matrix, which is a generalization of the well known LCFA scattering rates. We find spin-dependent expressions that may be included in electromagnetic charged-particle simulation codes, such as particle-in-cell plasma simulation codes, using Monte-Carlo modules. In particular, these expressions include the spin-flip rates for arbitrary initial polarization of the electrons. The validity of the LCFA is confirmed by explicit comparison with an exact QED calculation of electron polarization in an ultrashort laser pulse.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑