Potential-driven Galileon inflation

Junko Ohashi*, Shinji Tsujikawa

*この研究の対応する著者

研究成果: Article査読

52 被引用数 (Scopus)

抄録

For the models of inflation driven by the potential energy of an inflaton field φ, the covariant Galileon Lagrangian (φ) 2φ generally works to slow down the evolution of the field. On the other hand, if the Galileon self-interaction is dominant relative to the standard kinetic term, we show that there is no oscillatory regime of inflaton after the end of inflation. This is typically accompanied by the appearance of the negative propagation speed squared c s 2 of a scalar mode, which leads to the instability of small-scale perturbations. For chaotic inflation and natural inflation we clarify the parameter space in which inflaton oscillates coherently during reheating. Using the WMAP constraints of the scalar spectral index and the tensor-to-scalar ratio as well, we find that the self coupling λ of the potential V(φ) = λφ 4/4 is constrained to be very much smaller than 1 and that the symmetry breaking scale f of natural inflation cannot be less than the reduced Planck mass M pl. We also show that, in the presence of other covariant Galileon Lagrangians, there are some cases in which inflaton oscillates coherently even for the self coupling λ of the order of 0.1, but still the instability associated with negative c s 2 is generally present.

本文言語English
論文番号035
ジャーナルJournal of Cosmology and Astroparticle Physics
2012
10
DOI
出版ステータスPublished - 2012 10
外部発表はい

ASJC Scopus subject areas

  • 天文学と天体物理学

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