Non-Gaussianity in two-field inflation beyond the slow-roll approximation
In this talk, I will discuss the level of bispectral non-Gaussianity produced in two-field inflation models with standard kinetic terms. Even though the Planck satellite has so far not detected any primordial non-Gaussianity, it has tightened the constraints significantly, and it is important to better understand what regions of inflation model space have been ruled out, as well as prepare for the next generation of experiments that might reach the important milestone of \(\Delta f_{NL}^\mathrm{local} = 1 \) .
I will present our results on the non-Gaussianity parameter \(f_{NL}\) in the case of sum potentials and show that it is very difficult to satisfy simultaneously the conditions for a large \(f_{NL}\) and the observational constraints on the spectral index \(n_s \) in the slow-roll approximation. I will then discuss the case of monomial potentials and show explicitly the small region of parameter space in which this is possible.
Finally, I will extend these results beyond the slow-roll approximation and illustrate them with two explicit inflation models.