Speaker
Dongwoo Kang
(KIAS)
Description
A kinetic coupling between photon and dark photon, a massless $U(1)$ gauge boson in the dark sector, transfers the birefringence of dark photon to the observed cosmic birefringence. Regardless of the origin of the dark birefringence, the amplitude and unique frequency-dependence of the cosmic birefringence depends on the kinetic coupling constant and the temperature of dark photon. To explain the reported tantalizing 3.6$\sigma$ hint of cosmic birefringence, the dark photon temperature must exceed 0.84\,{\rm K}, whose contribution to $\Delta N_{\rm eff}$ might be within reach of the CMB Stage-4.
Primary authors
Dongwoo Kang
(KIAS)
Sung Mook Lee
(Yonsei University)
Co-authors
Jinn-Ouk Gong
(Ewha Womans University)
Donghui Jeong
(Pennsylvania State University & KIAS)
Dong-Won Jung
(Yonsei University)
Seongchan Park
(Yonsei University)
