Starts 22 Apr 2016 16:30
Ends 22 Apr 2016 18:00
Central European Time
ICTP
Leonardo Building - Euler Lecture Hall
Abstract. In this talk, I will talk about a single field axion inflation model in the presence of an SU(2) gauge field with a small vev. The gauge field is coupled to the axion with a Chern-Simons interaction and has a negligible effect on the background evolution. However, its quantum fluctuations make a significant contribution to the cosmic perturbation. In particular, the gauge field has a spin-2 fluctuation which explicitly breaks the parity between the left- and right-handed polarization states. The chiral tensor modes are linearly coupled to the gravitational waves and generates a circularly polarized tensor power spectrum compatible with the unpolarized vacuum fluctuations. Moreover, the scalar sector is modified by the linear scalar fluctuations of the gauge field. Since the spin-0 and spin-2 fluctuations of the SU(2) gauge field are independent, the gauge field can, at the same time, generate a detectable chiral gravitational wave signal and have a negligible contribution to the scalar fluctuations, in agreement with the current CMB observations.
--- Please note change of day and venue!! ---