Time-domain properties of electromagnetic signals in a dynamical axion background
Time-domain properties of electromagnetic signals in a dynamical axion background
复制标题
DOI：
10.1103/physrevd.102.123011
复制
发表时间：
2020-07
期刊：
影响因子：
--
通讯作者：
Peter Adshead;P. Draper;B. Lillard
中科院分区：
文献类型：
--
作者：
Peter Adshead;P. Draper;B. Lillard
动态轴子背景中的电磁波在高频下表现出超光速群速度，在低频下表现出不稳定性，从而改变了光子在空间中传播的方式。局部扰动因果传播，但与普通麦克斯韦理论不同，传播发生在光锥内部和光锥上。对于不稳定模式，电磁场中的能量密度随着类时位移呈指数增长。在本文中，我们推导了轴子电动力学中各种极限下的延迟格林函数，并研究了传播信号的时域特性。
Electromagnetic waves in a dynamical axion background exhibit superluminal group velocities at high frequencies and instabilities at low frequencies, altering how photons propagate through space. Local disturbances propagate causally, but unlike in ordinary Maxwell theory, propagation occurs inside as well as on the lightcone. For the unstable modes, the energy density in the electromagnetic field grows exponentially along timelike displacements. In this paper we derive retarded Green functions in axion electrodynamics in various limits and study the time-domain properties of propagating signals.