Studies On The Effects Of Photon Rest Mass In The Optical Experiments Searching For The Axions And The Combination Of The Mass Limits Of Axion

Axion is a hypothetical elementary particle which emerged from a compelling solution to the Strong-CP problem in QCD. Subsequently, the axion was recognized to be a good Cold Dark Matter candidate. Although dark matter axions have only feeble couplings to matter and radiation, extremely sensitive searches are underway around the world. Besides solving the strong CP problem in QCD, the discovery of axions may be very meaningfull to the quantum field theories, particle physics and cosmology.We review the origin and models of the axion, as well as the state of experiments searching for it through its coupling to photons and protons. And we have deduced the relationship between the couplings of axion to protons and to photons after renormalization by working within the framework of perturbation theory. Then we get the mass limits of axion from the torsion balance experiments which devoted to test the Weak Equivalence Principle (WEP) and the Gravitational Inverse Square Law (ISL) after transformation.Maxwell classical electromagnetic theory and the special theory of relativity,quantum electrodynamics constitute the fundamental frames of the electromagnetic interactions which transformed by photons . One of the major contributions of them is that they defined the speed of electromagnetic wave in vacuum as the constant speed of light c,which implies a hypothesis that the photon rest mass must be zero exactly. But whether this rest mass is zero or not, is still one of the fundamental problems confronted by many physicists. All experiments which devoted to test the rest mass of photon were only obtained the upper constrains on it up to now. Any conclusive evidence of a finite rest mass for the photon will bring great influence on development of the whole physics. So, we have explored the effects of nonzero photon rest mass in the high-precision experiment which devoted to search for the axions by using the laser beam traveling through a strong magnetic field based on the massive electromagnetic field theory. Then we compared the results which implied by this experiment with the limits of photon rest mass presented by using modulated torsion balance in our laboratory in 2003. we found that the effects of nonzero photon rest mass in this experiment is very smaller than the mass limit of axion,and the sensitivity of the implied limit of the photon rest mass is very poorer than ours. So it shows that the torsion balance is still an effective measure to detect the photon rest mass.This work was supported by the National Natural Science Foundation of China (10121503).