Astroparticle-physics search for Lorentz violation in the photon sector

时空是动态的，量子力学具有内在的随机性。这意味着空间在非常小的尺度上可能不是完全光滑的，洛伦兹不变性可能从根本上被破坏。洛伦兹不变性的一个理想测试场是光子区。有19个无量纲参数，其中10个导致真空双折射，并已限制在10-32的水平。最紧迫的任务是约束非双折射修正的麦克斯韦理论的其余9个参数。在这9个参数中，单个各向同性参数是最难在实验室中约束或确定的。申请人从超高能宇宙射线（皮埃尔俄歇天文台）和TeV伽马射线（H.E.S.S.）获得了最佳间接边界。这个项目的目的是改善这些边界至少两个数量级，这是特别重要的各向同性参数。在实验方面，这需要构建适当的俄歇数据样本。在理论方面，能量阈值条件必须加以改进，以考虑到质子不是点粒子这一事实。此外，总有可能发现洛伦兹破坏效应。出于这个原因，这个项目的一个重要部分是专门的搜索策略和初步扫描的可用数据从俄歇。探测光子扇区中的洛伦兹破坏和提取极紧的上界对整个物理学都很重要，当然是以不同的方式。

Spacetime is dynamic and quantum mechanics inherently random. This suggests that space may not be perfectly smooth at very small length scales and that Lorentz invariance may be fundamentally violated. An ideal testing ground of Lorentz invariance is the photon sector. There are 19 dimensionless parameters, of which 10 lead to vacuum birefringence and are already constrained at the 10-32 level. The most urgent task is to bound the remaining 9 parameters of the nonbirefringent modified Maxwell theory. Of these 9 parameters, the single isotropic parameter is the most difficult to bound or determine in the laboratory. The best indirect bounds were obtained by the applicants from ultra-high-energy cosmic rays (Pierre Auger Observatory) and TeV gamma-rays (H.E.S.S.). This project aims at improving these bounds by at least two orders of magnitude which is especially important for the isotropic parameter. On the experimental side, this requires the construction of an appropriate Auger data sample. On the theoretical side, the energy-threshold conditions must be refined to incorporate the fact that the proton, for example, is not a point particle. In addition, there is always the possibility of discovery of Lorentz-violating effects. For this reason, a significant part of this project is devoted to search strategies and a preliminary scan of the available data from Auger. Both the detection of Lorentz violation in the photon sector and the extraction of extremely tight upper bounds would be of importance to physics as a whole, but in a different way, of course.