6 research outputs found
Consistency condition for inflation from (broken) conformal symmetry
We investigate the symmetry constraints on the bispectrum, i.e. the
three-point correlation function of primordial density fluctuations, in
slow-roll inflation. It follows from the defining property of slow-roll
inflation that primordial correlation functions inherit most of their structure
from weakly broken de Sitter symmetries. Using holographic techniques borrowed
from the AdS/CFT correspondence, the symmetry constraints on the bispectrum can
be mapped to a set of stress-tensor Ward identities in a weakly broken
2+1-dimensional Euclidean CFT. We construct the consistency condition from
these Ward identities using conformal perturbation theory. This requires a
second order Ward identity and the use of the evolution equation. Our result
also illustrates a subtle difference between conformal perturbation theory and
the slow roll expansion.Comment: 13 pages, 2 figures; v2, published versio
The everpresent eta-problem: knowledge of all hidden sectors required
We argue that the eta-problem in supergravity inflation cannot be solved
without knowledge of the ground state of hidden sectors that are
gravitationally coupled to the inflaton. If the hidden sector breaks
supersymmetry independently, its fields cannot be stabilized during
cosmological evolution of the inflaton. We show that both the subsequent
dynamical mixing between sectors as well as the lightest mass of the hidden
sector are set by the scale of supersymmetry breaking in the hidden sector. The
true cosmological eta-parameter arises from a linear combination of the
lightest mode of the hidden sector with the inflaton. Generically, either the
true eta deviates considerably from the na\"ive eta implied by the inflaton
sector alone, or one has to consider a multifield model. Only if the lightest
mass in the hidden sector is much larger than the inflaton mass and if the
inflaton mass is much larger than the scale of hidden sector supersymmetry
breaking, is the effect of the hidden sector on the slow-roll dynamics of the
inflaton negligible.Comment: 27 pages, 6 figures; v2, published version, minor adjustments to the
introduction, minor corrections to section 2.2 for improved clarity,
references adde
Consistency condition for inflation from (broken) conformal symmetry
We investigate the symmetry constraints on the bispectrum, i.e. the three-point correlation function of primordial density fluctuations, in slow-roll inflation. It follows from the defining property of slow-roll inflation that primordial correlation functions inherit most of their structure from weakly broken de Sitter symmetries. Using holographic techniques borrowed from the AdS/CFT correspondence, the symmetry constraints on the bispectrum can be mapped to a set of stress-tensor Ward identities in a weakly broken 2+1-dimensional Euclidean CFT. We construct the consistency condition from these Ward identities using conformal perturbation theory. This requires a second order Ward identity and the use of the evolution equation. Our result also illustrates a subtle difference between conformal perturbation theory and the slow-roll expansion