近日，巴西里约热内卢联邦大学的M. J. Neves及其研究团队取得一项新进展。经过不懈努力，他们对QED真空中非线性、轴子和时空各向异性效应之间的干扰进行探究。相关研究成果已于2024年5月3日在国际知名学术期刊《高能物理杂志》上发表。

在本文中，研究人员深入探讨了Carroll-Field-Jackiw（CFJ）场景下洛伦兹对称违反（LSV）的轴子电动力学的一般非线性扩展。该模型通过任意非线性电动力作用与轴子场的耦合，实现了在粒子层面上对洛伦兹对称性的破缺，这一破缺是在特定各向异性四矢量的影响下实现的。研究中，研究人员将非线性电磁场在恒定且均匀的磁背景中展开至二阶，以便更精确地分析光子场的传播。

他们特别关注在类空间CFJ-4向量下，真空的材料性质，并明确推导出了在两种不同磁场方向（垂直于波方向和平行于波方向）下与平面波解相关的色散关系。此外，研究人员还分析了非线性条件下的双折射现象，并探讨了轴子和LSV如何通过空间各向异性表现出来。他们考虑了欧拉-海森堡（EH）、玻恩-因菲尔德（BI）和修正麦克斯韦电动力学（ModMax）这三种具体的非线性电动力学模型。

在整篇论文中，研究人员将解释为什么他们遵循不寻常的路径，在单一拉格朗日密度中，连接标准模型之外的三个物理部分，即非线性，轴子和LSV。研究人员预计，他们不会声称在标准模型之外同时引入这三个主题将为检测轴子或约束与非线性电动力学和LSV物理相关的参数的努力带来新的见解或线索。他们真正的目标是在外部恒定且均匀的磁场环境下，通过计算群速度、折射率、双折射和物理激发的有效质量等物理量，来深入研究和描述轴子、非线性和洛伦兹对称违反（LSV）效应之间是如何相互干扰的。

附：英文原文

Title: Probing the interference between non-linear, axionic and space-time-anisotropy effects in the QED vacuum

Author: Paixao, J. M. A., Ospedal, L. P. R., Neves, M. J., Helayel-Neto, J. A.

Issue&Volume: 2024-05-03

Abstract: In this paper, we pursue the investigation of a generic non-linear extension of axionic electrodynamics in a Carroll-Field-Jackiw (CFJ) scenario that implements Lorentz-symmetry violation (LSV). The model we inspect consists of an arbitrary non-linear electrodynamic action coupled to the axion field in presence of an anisotropy four-vector that realizes the breaking of Lorentz symmetry under the particle point of view. For the sake of our considerations, the non-linear electromagnetic field is expanded around a constant and uniform magnetic background up to second order in the propagating photon field. The focus of our attention is the study of the material properties of the vacuum in the particular case of a space-like CFJ 4-vector. The dispersion relations associated to the plane wave solutions are explicitly worked out in two situations: the magnetic background perpendicular and parallel to the wave direction. We extend these results to consider the analysis of the birefringence phenomenon in presence of non-linearity, the axion and the LSV manifested through the spatial anisotropy. Three specific proposals of non-linear electrodynamics are contemplated: Euler-Heisenberg (EH), Born-Infeld (BI) and the Modified Maxwell electrodynamics (ModMax). Throughout the paper, we shall justify why we follow the unusual path of connecting, in a single Lagrangian density, three pieces of physics beyond the Standard Model, namely, non-linearity, axions and LSV. We anticipate that we shall not be claiming that the simultaneous introduction of these three topics beyond the Standard Model will bring new insights or clues for the efforts to detect axions or to constrain parameters associate to both non-linear electrodynamics and LSV physics. Our true goal is to actually inspect and describe how axionic, non-linear and LSV effects interfere with one another whenever physical entities like group velocity, refraction indices, birefringence and effective masses of physical excitations are computed in presence of an external constant and homogeneous magnetic field.

DOI: 10.1007/JHEP05(2024)029

Source: https://link.springer.com/article/10.1007/JHEP05(2024)029