Finite beaming effect on QED cascades

IF 4.3 2区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Physics Letters B Pub Date : 2024-11-17 DOI:10.1016/j.physletb.2024.139136

Suo Tang

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引用次数: 0

Abstract

The quantum electrodynamic (QED) theory predicts the photon emission and pair creation involved in QED cascades occur mainly in a forward cone with finite angular spread Δθ∼1/γi along the momenta of incoming particles. This finite beaming effect has been assumed to be negligible because of the particles' ultra-relativistic Lorentz factor γi≫1 in laser-driven QED cascades. We develop an energy- and angularly resolved particle-tracking code, resolving both the energy spectra and the momentum profile of the outgoing particles in each QED event, which improves substantially the agreement between the simulation and exact QED results. We investigate QED cascades driven by two counter-propagating circularly polarized laser pulses, and show that the narrow beaming could be accumulated to effectively suppress the long-term growth of cascades, even though it can hardly affect the early formation of cascades. For QED cascades longer than 10 laser cycles, the finite beaming effect could decrease the final pair yield, especially at ultrahigh intensities ξ>600, by more than 10%.

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QED 级联的有限束流效应

根据量子电动力学（QED）理论的预测，QED 级联中涉及的光子发射和光对产生主要发生在一个前向锥体中，其沿入射粒子矩的有限角散布Δθ∼1/γi。在激光驱动的 QED 级联中，由于粒子的超相对论洛伦兹因子 γi≫1 ，这种有限的束流效应被假定为可以忽略不计。我们开发了一种能量和角度解析的粒子跟踪代码，解析了每个 QED 事件中出射粒子的能量谱和动量谱，从而大大提高了模拟结果与精确 QED 结果之间的一致性。我们研究了由两个反向传播的圆偏振激光脉冲驱动的 QED 级联，结果表明，尽管窄束流很难影响级联的早期形成，但它可以通过累积来有效抑制级联的长期增长。对于长度超过10个激光周期的QED级联，有限光束效应会使最终成对率降低10%以上，尤其是在超高强度ξ>600下。

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来源期刊

Physics Letters B 物理-物理：综合

CiteScore

9.10

自引率

6.80%

发文量

647

审稿时长

3 months

期刊介绍： Physics Letters B ensures the rapid publication of important new results in particle physics, nuclear physics and cosmology. Specialized editors are responsible for contributions in experimental nuclear physics, theoretical nuclear physics, experimental high-energy physics, theoretical high-energy physics, and astrophysics.