2019-11-29 11:00  P7F

Tensor Non-Gaussianity from Axion-Gauge-Fields Dynamics

Aniket Agrawal

I will talk about an inflation model in which a spectator axion field coupled to an SU(2) gauge field produces a large three-point function (bispectrum) of primordial gravitational waves, on scales relevant to cosmic microwave background experiments. The amplitude of the bispectrum at the equilateral configuration is characterized by B_h/P_h² = 𝒪(10)× Ω_A^-1, where Ω_A is a fraction of the energy density in the gauge field and P_h is the power spectrum of gravitational waves produced by the gauge field. These gravitational waves are chiral, and can have a scale-independent power spectrum over a large range of wavenumbers, necessitating the measurement of TB and EB cross correlations along with measurement of non-Gaussianity to claim quantum fluctuations of the metric.