Abstract
We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy GabdaV3bV <C V2/Mp (where Gab is the target-space metric). They evade the usual slow-roll conditions on V because their kinetic energies are dominated by single-derivative terms rather than the usual two-derivative terms. Single derivatives dominate during slow roll and so do not require a breakdown of the usual derivative expansion that underpins calculational control in much of cosmology. The presence of such terms requires some sort of UV Lorentz-symmetry breaking during inflation (besides the usual cosmological breaking). Chromo-natural inflation provides one particular example of a UV theory that can generate the multi-field single-derivative terms we consider, and we argue that the EFT we find indeed captures the slow-roll conditions for its background evolution. We also show that our EFT can be understood as a multi-field generalization of the single-field Cuscuton models. The multi-field case introduces a new feature, however: the scalar kinetic terms define a target-space 2-form, Fab, whose antisymmetry gives new ways for slow roll to be achieved.
Original language | English (US) |
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Article number | 009 |
Journal | Journal of Cosmology and Astroparticle Physics |
Volume | 2016 |
Issue number | 11 |
DOIs | |
State | Published - Nov 4 2016 |
Keywords
- Inflation
- Particle physics - cosmology connection
ASJC Scopus subject areas
- Astronomy and Astrophysics