The (not so) squeezed limit of the primordial 3-point function

Abstract

We prove that, in a generic single-field model, the consistency relation for\nthe 3-point function in the squeezed limit receives corrections that vanish\nquadratically in the ratio of the momenta, i.e. as (k_L/k_S)^2. This implies\nthat a detection of a bispectrum signal going as 1/k_L^2 in the squeezed limit,\nthat is suppressed only by one power of k_L compared with the local shape,\nwould rule out all single-field models. The absence of this kind of terms in\nthe bispectrum holds also for multifield models, but only if all the fields\nhave a mass much smaller than H. The detection of any scale dependence of the\nbias, for scales much larger than the size of the haloes, would disprove all\nsingle-field models. We comment on the regime of squeezing that can be probed\nby realistic surveys.\n