Multi-field DBI inflation: introducing bulk forms and revisiting the gravitational wave constraints
Multi-field DBI inflation: introducing bulk forms and revisiting the gravitational wave constraints
We study multi-field Dirac-Born-Infeld (DBI) inflation models, taking into account the NS-NS and R-R bulk fields present in generic flux compactifications. We compute the second-order action, which governs the behaviour of linear cosmological perturbations, as well as the third-order action, which can be used to calculate non-Gaussianities in these models. …