Paolo Creminelli, Guido D'Amico, Marcello Musso, Jorge Noreña
We prove that, in a generic single-field model, the consistency relation for
the 3-point function in the squeezed limit receives corrections that vanish
quadratically in the ratio of the momenta, i.e. as (k_L/k_S)^2. This implies
that a detection of a bispectrum signal going as 1/k_L^2 in the squeezed limit,
that is suppressed only by one power of k_L compared with the local shape,
would rule out all single-field models. The absence of this kind of terms in
the bispectrum holds also for multifield models, but only if all the fields
have a mass much smaller than H. The detection of any scale dependence of the
bias, for scales much larger than the size of the haloes, would disprove all
single-field models. We comment on the regime of squeezing that can be probed
by realistic surveys.
View original:
http://arxiv.org/abs/1106.1462
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