Prerequisites for studying relativistic quantum dynamics in experiments at the GSI and FAIR facilities

本提案旨在就电子量子动力学理论(包括电子-正电子对的产生)和在强电磁场存在下的辐射过程开展强有力的合作。这些研究对于计划在GSI和FAIL设施进行的实验是必要的。这两个团队将致力于开发相对论方法来计算低能离子-原子碰撞中的电子激发、电荷转移和对产生过程。将以前发展的方法推广到含时密度泛函理论，使我们能够适当地解释电子间相互作用效应，并描述(准)对称低能离子-原子碰撞中的相对论多电子过程。研究低能重离子碰撞中的准分子辐射光谱具有特殊的意义。事实上，跃迁幅度与离子轨迹入射和出射部分的光子发射的相干叠加导致了辐射的干涉结构，这使得理论和实验之间可以进行详细的比较。对光谱强度和形状的分析将是研究超临界低能重离子-原子碰撞的各种过程和寻找新物理的有力工具。因此，将发展一种计算低能重离子碰撞中准分子辐射光谱的技术。通过这些扩展，将计算计划在CRYRING(Darmstadt)研究的低能重离子-原子碰撞中的各种过程的概率。此外，还将计算离子-原子(-离子)在库仑势垒附近的入射能量下的电荷转移、电离和对产生几率，包括考虑狄拉克连续谱的所有占据的负能态。这两个团队还将致力于开发一种相对论技术，用于描述暴露在强激光场中的高电荷态离子。非偶极子效应的作用，负能量狄拉克连续体和自旋不对称效应在这些过程中的影响将被研究。还将发展一种相对论方法来描述扭曲电子与各种离子和原子系统的相互作用。我们将对涡旋电子束与重高电荷态离子的辐射复合和双电子复合进行相对论计算。所有工作都将与GSI/FIRE(该项目中德国团队的一部分)的实验员密切合作完成，从而确保对相应的即将到来的实验进行最佳规划和准备，以便能够处理低能离子碰撞领域中最有趣的物理现象。

The present proposal aims at implementing a strong collaboration working on the theory of quantum dynamics of electrons (including electron-positron pair creation) and radiation processes in presence of strong electromagnetic fields. These studies are needed for experiments that are planned to be performed at the GSI and FAIR facilities. The teams will work on development of relativistic methods for calculations of the electron-excitation, charge-transfer, and pair-creation processes in low-energy ion-atom collisions. The previously developed approach will be extended to the time-dependent density functional theory that will allow us to properly account for interelectronic-interaction effects and describe relativistic many-electron processes in (quasi) symmetric low-energy ion-atom collisions. The study of quasimolecular radiation spectra at low-energy heavy-ion collisions is of special interest. Indeed, the coherent superposition of the transition amplitudes with the photon emission in the incoming and outgoing part of the ion trajectories leads to an interference structure of radiation, which allows a detailed comparison between theory and experiment. The analysis of the intensity and shape of the spectra will be a powerful tool for studying various processes and searching for new physics in low-energy heavy ion-atom collisions at the supercritical regime. Thus, a technique for calculations of the quasimolecular radiation spectra at low-energy heavy-ion collision will be developed. With these extensions, the probabilities of various processes in low-energy heavy ion-atom collisions, that are planned to be investigated at the CRYRING (Darmstadt), will be calculated. Also the calculations of the charge-transfer, ionization, and pair-creation probabilities in ion-atom (-ion) collisions at the projectile energies near the Coulomb barrier will be performed including into consideration all occupied negative-energy states of the Dirac continuum. The teams will also work on the development of a relativistic technique for describing of highly charged ions exposed to strong laser fields. The role of non-dipole effects, the influence of the negative-energy Dirac continuum and spin-asymmetry effects in these processes will be investigated. A relativistic approach for describing the interaction of twisted electrons with various ionic and atomic systems will be also developed. Relativistic calculations of the radiative and dielectronic recombinations of the vortex electron beams with heavy highly charged ions will be performed. All the work will be done in close collaboration with the experimentalists from GSI/FAIR (part of the German team in this project), thus ensuring an optimal planning and preparation of the corresponding upcoming experiments to allow for addressing the most interesting physics phenomena in the realm of low-energy ion collisions.