http://arxiv.org/abs/2211.14324
The four-point correlation function of primordial scalar perturbations has parity-even and parity-odd contributions, and the parity-odd signal in cosmological observations is opening a novel window to look for new physics in the inflationary epoch. We study the distinct parity-odd and even prediction from the axion inflation model, in which the inflaton couples to a vector field via a Chern-Simons interaction, and the vector field is considered to be either approximately massless ($m_A \ll $ the Hubble scale $H$) or very massive ($m_A \sim H $). The parity-odd signal arises due to one transverse mode of the vector field being predominantly produced during inflation. We adopt the in-in formalism to evaluate the correlation functions. Considering the vector field mode function to be dominated by its real part up to a constant phase, we simplify the formulas for numerical computations. The numerical studies show that the massive and massless vector fields give significant parity-even signals, while the parity-odd signals are about one to two orders of magnitude smaller.
X. Niu, M. Rahat, K. Srinivasan, et. al.
Tue, 29 Nov 22
80/80
Comments: 21 pages, 10 figures