162 citations · 654 across the 7 of their papers we have counts for
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Primordial non-Gaussianity from the DBI Galileons
Shuntaro Mizuno, Kazuya Koyama
We study primordial fluctuations generated during inflation in a class of models motivated by the DBI Galileons, which are extensions of the DBI action that yield second order fiel…
On the full quantum trispectrum in multi-field DBI inflation
Shuntaro Mizuno, Frederico Arroja, Kazuya Koyama
We compute the leading order connected four-point function of the primordial curvature perturbation coming from the four-point function of the fields in multi-field DBI inflation m…
Lorentz boost and non-Gaussianity in multi-field DBI-inflation
Shuntaro Mizuno, Frederico Arroja, Kazuya Koyama +1
We show that higher-order actions for cosmological perturbations in the multi-field DBI-inflation model are obtained by a Lorentz boost from the rest frame of the brane to the fram…
Non-Gaussianities from ekpyrotic collapse with multiple fields
Kazuya Koyama, Shuntaro Mizuno, Filippo Vernizzi +1
We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-…
Curvature perturbations from ekpyrotic collapse with multiple fields
Kazuya Koyama, Shuntaro Mizuno, David Wands
A scale-invariant spectrum of isocurvature perturbations is generated during collapse in the ekpyrotic scaling solution in models where multiple fields have steep negative exponent…
Slow-roll corrections to inflaton fluctuations on a brane
Kazuya Koyama, Shuntaro Mizuno, David Wands
Quantum fluctuations of an inflaton field, slow-rolling during inflation are coupled to metric fluctuations. In conventional four dimensional cosmology one can calculate the effect…