The Cosmological Research Of Axion And Axion-like Particle

Two years after Einstein established general relativity in the 1915,he began to use it to study the evolution of the universe,to obtain a model of the universe that evolved over time,and later to add a constant in the equation,called the cosmological constant,to ensure that the universe is static,because it is subjective to think that the universe should be immutable.Later,in 1929,Hubble discovered for the first time,through modern astronomical observation techniques,that the universe was expanding,and the farther away the stars were from the Earth,the phenomenon was summed up as the Hubble law.In this way,the academic community generally endorses the Friedman cosmic model.The cosmological constants were not completely discarded,and later observations based on the hight red shift of Ia Supernova,showed that the universe was accelerating its expansion.Cosmic microwave background radiation,as the first experimental evidence to support and greatly promote the development of cosmology in the strict sense,with the continuous improvement of its measurement accuracy,its temperature also shows consistent to primordial density fluctuations.The recent Wilkinson Microwave background radiation Detector(WMAP)and Planck satellite Detector(PLANK)have found a large-scale anomaly,that is,the presence of hemispheric power spectrum asymmetry in background radiation spectra.The theoretical interpretation and study of it is of great significance to the clarity of the early evolution of the universe,but also has an important enlightening effect on the problem of dark matter and dark energy,which can provide different solutions for the new physics,and it has become a hot topic in the study of cosmology.The understanding of it helps us to understand the early evolution of the universe,the process of the inflation of the universe and the mechanism of its fluctuations on the formation of the large scale structure of the universe.Galactic rotation curves and gravitational lens effects all indicate the existence of different material forms in the universe from ordinary matter,that is,so-called dark matter.Dark matter and dark energy became the ”two dark clouds” of physics in the 21 st century,thus becoming a hot topic in physics research.The axions are derived from the strong CP problem of particle physics and can be created from the so-called misalignment mechanism.This thesis first introduces the establishment of cosmological model and the problems encountered in the development of cosmology.Next,the discovery and significance of CMB radiation,the progress of experiments are discussed.Wilkinson Microwave background radiation anisotropy detector and Planck detector are the most advanced observation methods,and by analyzing the spectrum of microwave background,it is shown that there is a large scale asymmetry on the observable cosmic scale,and it is a very strong scale dependent.As one of the candidates for dark matter,axions and axion-like particles may play an extremely important role in the very early universe,and after study we find that the cosmic strings of the axion-like particles(ALP)formed are adjacent to our cosmic region and can naturally explain the asymmetry.We found that cosmic strings produced a field variation around itself and then became particle density fluctuations after the inflation.As a result,It leads to the now observed hemispheric power asymmetry.