We calculate the trispectrum of the primordial curvature perturbation generated by an epoch of slow-roll inflation in the early universe , and demonstrate that the non-gaussian signature imprinted at horizon crossing is unobservably small , of order \tau _ { \mathrm { NL } } \lesssim r / 50 , where r < 1 is the tensor-to-scalar ratio .
Therefore any primordial non-gaussianity observed in future microwave background experiments is likely to have been synthesized by gravitational effects on superhorizon scales .
We discuss the application of Maldacena ’ s consistency condition to the trispectrum .

Keywords : Inflation , Cosmological perturbation theory , Physics of the early universe .