Interactions at extremely high electromagnetic energy densities and QED processes in supercritical fields

下一代激光设施目前正在全球各地建设，包括欧洲的ELI项目、德国德累斯顿的北极星激光器和俄罗斯下诺夫哥罗德的XCELS激光器。与此同时，多GeV线性电子对撞机正在DESY(德国)和SLAC(美国)高级加速器实验测试设施(FEET)运行。计划将它们与强大的飞秒光学激光相结合。在激光技术和常规以及基于等离子体的粒子加速方法中的特殊进展为强场量子电动力学(IFQED)效应的实验研究打开了独特的机会，包括那些几乎尚未被探索的效应，例如高阶(根据精细结构常数)辐射修正。当一个超相对论粒子在适当的参考系中的场强超过Schwinger值高达1000倍时，IFQED辐射修正可能变得重要。在这方面特别令人感兴趣的是最近提议的第二方面设施的中期逐步升级。它的目标是创造一种极端的光束对撞机，它具有100 GeV的轻子束，携带兆安培电流，并聚焦到纳米级。因此，相互作用点的团簇密度将首次超过康普顿密度。当极高能量的轻子与极端的场和能量密度相互作用时，我们将面临一种新的机制。我们的建议旨在发展这种超临界IFQED制度的理论和模型。我们将探索(I)反向传播的强流轻子束的相互作用和(Ii)极短和强烈的电磁脉冲与超相对论电子的相互作用。在这两个装置中，假设粒子的动态量子参数远大于1。此外，它可能非常高(高达1000)，以至于必须考虑高阶IFQED辐射修正(高度超临界IFQED体制)。我们建议计算基本IFQED过程的概率，对此必须对现有的理论方法进行实质性的重新考虑。所获得的分析结果将在我们的QED-PIC程序VLPL和Quill中实现。修改后的程序将被用来模拟高度超临界区域的激光-光束和光束-光束相互作用，这与未来的强流轻子对撞机和极强激光脉冲有关。我们的结果可能对天体物理学有很大的兴趣，在天体物理学中，某些现象的描述需要假设超临界磁场和超相对论喷流的相互作用。在IFQED和极端相对论等离子体中非线性过程建模的交界处提出的工作计划是独一无二的，在某些方面符合(在某些方面甚至超过)该领域的国际先进水平

The next generation of laser facilities is now under construction around the globe, including the European project ELI, the POLARIS laser in Dresden (Germany) and the XCELS laser in Nizhny Novgorod (Russia). At the same time, multi-GeV linear electron colliders are in operation at DESY (Germany) and at the Facility for Advanced Accelerator Experimental Tests (FACET) at SLAC (USA). It is planned to combine both of them with powerful femtosecond optical lasers.Spectacular progress both in the laser technology and in conventional as well as in plasma-based methods for particle acceleration opens unique opportunities for experimental studies of Intense Field Quantum Electrodynamics (IFQED) effects, including those yet almost unexplored, such as high-order (in terms of the fine structure constant) radiative corrections.When the field strength in a proper reference frame of an ultrarelativistic particle exceeds the Schwinger value by a factor up to 1000, IFQED radiative corrections may become significant. In this context of exceptional interest is the recently proposed medium-term progressive upgrade of the FACET-II facility. It aims at the creation of an extreme beam collider with 100 GeV lepton beams carrying Mega-Ampere currents and focused to nanometer scale. Thus for the first time the bunch density at the interaction point will exceed the Compton density. We will face a novel regime when extremely high energy leptons interact with extreme fields and energy densities. A theoretical description is currently missing here.Our proposal aims at the development of both theory and modeling of such supercritical IFQED regimes. We will explore (i) the interaction of counter-propagating high-current lepton beams and (ii) the interaction of extremely short and intense electromagnetic pulses with ultrarelativistic electrons. In both setups the dynamic quantum parameter of the particles is assumed much higher than 1. Moreover, it can be so high (up to 1000) that high-order IFQED radiative corrections have to be taken into account (highly supercritical IFQED regime). We propose to calculate the probabilities of the basic IFQED processes in this regime, for which the existing theoretical approaches must be reconsidered substantially.The obtained analytical results will then be implemented in our QED-PIC codes VLPL and QUILL. The modified codes will be used to simulate the laser-beam and beam-beam interactions in a highly supercritical regime, relevant for the future high-current lepton colliders and extreme intensity laser pulses.Our results may be of substantial interest for astrophysics, where the description of certain phenomena requires the postulation of supercritical magnetic fields and the interaction of ultrarelativistic jets. The proposed workplan at the junction of IFQED and modeling of the nonlinear processes in ultrarelativistic plasmas is unique and corresponds to (in certain aspects even surpasses) the advanced international level in the field