Inflation driven by the Galileon field |
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Authors: | Kobayashi Tsutomu Yamaguchi Masahide Yokoyama Jun'ichi |
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Institution: | Research Center for the Early Universe, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan. |
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Abstract: | We propose a new class of inflation model, G inflation, which has a Galileon-like nonlinear derivative interaction of the form G(?,(??)(2))□? in the Lagrangian with the resultant equations of motion being of second order. It is shown that (almost) scale-invariant curvature fluctuations can be generated even in the exactly de Sitter background and that the tensor-to-scalar ratio can take a significantly larger value than in the standard inflation models, violating the standard consistency relation. Furthermore, violation of the null energy condition can occur without any instabilities. As a result, the spectral index of tensor modes can be blue, which makes it easier to observe quantum gravitational waves from inflation by the planned gravitational-wave experiments such as LISA and DECIGO as well as by the upcoming CMB experiments such as Planck and CMBpol. |
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