CMB Non-gaussianity from vector fields.

The Planck satellite has recently measured the CMB temperature anisotropies with unprecedented accuracy, and it has provided strong bounds on primordial non-gaussianity. Such bounds constrain models of inflation, and mechanisms that produce the primordial perturbations. We discuss the non-gaussian signatures from the interactions of the inflation Φ with spin-1 fields. We study the two different cases in which the inflaton is (i) a pseudo-scalar field with a Φ/faFF interaction with a vector field, and (ii) a scalar field with a f(Φ)F² interaction. In the first case we obtain the strong limit fa ≳ 10¹⁶GeV on the decay constant. In the second case, specific choices of the function f (Φ ) can lead to a non-gaussianity with a characteristic shape not encountered in standard models of scalar field inflation, and which has also been constrained by Planck. [ABSTRACT FROM AUTHOR]