We are delighted to announce the upcoming High-Energy Theory Seminar by Dr. Sung Mook Lee who joined KAIST recently as a postdoctoral fellow.

The seminar will take place today Wednesday (Sep 13) at 4PM at E6-2, #2502 and you are all invited to participate. 

 

 

Title: Cosmic Birefringence from Dark Photon

 

Recent findings of isotropic cosmic birefringence within CMB have sparked interest in exploring potential indications of parity violation in our universe. The prevailing interpretation is the existence of an axion background, a concept I will briefly review. On the other hand, my focus in this presentation will be the intriguing possibility of kinetic mixing between the CMB photons and birefringent dark photons as the underlying cause of cosmic birefringence. During this discussion, I will demonstrate that indeed the birefringence of the dark photons can influence the polarization of CMB photons even though this effect may not be uniformly distributed. Furthermore, our result sheds light on the pivotal role played by kinetic mixing in generating two fundamental attributes of the CMB: circular polarization and spectral distortion. This presentation is based on 2307.14798.