标题： 3D爱因斯坦-麦克斯韦理论的辐射渐近对称性 显示英文标题

标题： Radiative Asymptotic Symmetries of 3D Einstein-Maxwell Theory

摘要： 我们研究三维(3D)时空中爱因斯坦-麦克斯韦理论的零渐近结构。 尽管缺乏体内的引力自由度，该系统包含一个无质量的光子，因此可以容纳电磁辐射。 我们推导出麦克斯韦场的衰减条件，这些条件包含具有非零新闻的库仑模式和辐射模式。 后者会导致渐近表面电荷的不可积性和通量，并产生非平凡的3D Bondi质量损失公式。 因此，所得解空间类似于4D纯引力的维度约化，其中引力辐射的作用由其电磁对应物来承担。 我们利用这个简化的设置详细研究电荷括号的选择，并特别计算了最近引入的Koszul括号。 当应用于Wald-Zoupas电荷时，这些电荷在没有新闻的情况下是守恒的，它会导致之前在[arXiv:1503.00856]中发现的与场相关的中心扩张。 我们还考虑了(反-)德西特渐近情况，以进一步展示该模型与具有泄漏边界条件的4D引力之间的类比。 显示英文摘要

摘要： We study the null asymptotic structure of Einstein-Maxwell theory in three-dimensional (3D) spacetimes. Although devoid of bulk gravitational degrees of freedom, the system admits a massless photon and can therefore accommodate electromagnetic radiation. We derive fall-off conditions for the Maxwell field that contain both Coulombic and radiative modes with non-vanishing news. The latter produces non-integrability and fluxes in the asymptotic surface charges, and gives rise to a non-trivial 3D Bondi mass loss formula. The resulting solution space is thus analogous to a dimensional reduction of 4D pure gravity, with the role of gravitational radiation played by its electromagnetic cousin. We use this simplified setup to investigate choices of charge brackets in detail, and compute in particular the recently introduced Koszul bracket. When the latter is applied to Wald-Zoupas charges, which are conserved in the absence of news, it leads to the field-dependent central extension found earlier in [arXiv:1503.00856]. We also consider (Anti-)de Sitter asymptotics to further exhibit the analogy between this model and 4D gravity with leaky boundary conditions.