Tuesday, March 12, 2013

1303.2125 (Kazuya Koyama et al.)

Orthogonal non-Gaussianity in DBI Galileon: constraints from WMAP9 and prospects for Planck    [PDF]

Kazuya Koyama, Guido Walter Pettinari, Shuntaro Mizuno, Christian Fidler
In this note, we study constraints on primordial non-Gaussianity in DBI Galileon models in which an induced gravity term is added to the Dirac-Born-Infeld (DBI) action. In this model, the non-Gaussianity of orthogonal shape can be generated, which is slightly favoured by WMAP nine-year (WMAP9) data. We provide a relation between theoretical parameters and orthogonal/equilateral non-linear parameters using the Fisher matrix approach. In doing so, we include the effect of the CMB transfer functions and Planck noise properties by employing the recently developed \textsf{SONG} code. The relation is also shown in the effective theory language so that it can be applied to general single-field models. Using the bispectrum Fisher matrix for Planck, we derive forecasts for constraints on the theoretical parameters. We find that Planck can rule out the conventional DBI inflation model at a statistically significant level, provided that it measures the same central values as WMAP9 for equilateral and orthogonal non-Gaussianities.
View original: http://arxiv.org/abs/1303.2125

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