论文标题
在原始磁场存在下轴的演变
Evolution of axions in the presence of primordial magnetic fields
论文作者
论文摘要
我们研究了与原始磁场（PMF）相互作用的轴的演变，仅从扩展宇宙中的QCD相变。这种相互作用是由于Primakoff效应。采用轴的零模式近似，我们得出了轴和磁场的方程系统，其中宇宙的膨胀和磁场的光谱被准确地解释了。我们发现，Primakoff效应对轴和磁场动力学的贡献相当弱。它证实了一些先前的估计，导致了类似结论，当在此考虑到均匀轴突场的哈勃膨胀和使用傅立叶光谱的均匀轴磁场和非均匀PMF时，其能量和螺旋密度。我们求解了进化方程的相应系统，并发现轴上零模式在辐射时代演变时，其幅度在足以使该轴的水平上是冷暗物质的良好候选者。
We study the evolution of axions interacting with primordial magnetic fields (PMFs) starting just from the QCD phase transition in the expanding universe. This interaction is owing to the Primakoff effect. Adopting the zero mode approximation for axions, we derive the system of equations for axions and magnetic fields, where the expansion of the universe and the spectra of magnetic fields are accounted for exactly. We find that the contribution of the Primakoff effect to the dynamics of axions and magnetic fields is rather weak. It confirms some previous estimates leading to analogous conclusions, when accounting here for the Hubble expansion both for an uniform axion field and non-uniform PMFs using Fourier spectra for their energy and helicity densities. We solve the corresponding system of the evolution equations and find that the axion zero mode, when evolving during radiation era, has its amplitude at the level sufficient for that axion to be a good candidate for the cold dark matter.
