Constraining PCP Violating Varying Alpha Theory Through Laboratory   Experiments
  In this report we have studied the implication of a parity and charge-parity (PCP) violating interaction in varying alpha theory. Due to this interaction, the state of photon polarization can change when it passes through a strong background magnetic field. We have calculated the optical rotation and ellipticity of the plane of polarization of an electromagnetic wave and tested our results against different laboratory experiments. Our model contains a PCP violating parameter $\beta$ and a scale of alpha variation $\omega$. By analyzing the laboratory experimental data, we found the most stringent constraints on our model parameters to be $1\leq \omega \leq 10^{13} GeV^2$ and $-0.5\leq \beta \leq 0.5$. We also found that with the existing experimental input parameters it is very difficult to detect the ellipticity in the near future. 
Debaprasad Maity, Pisin Chen
hep-ph