Power spectrum of stochastic wave and diffusion equations in the warm inflation models
Abstract We discuss dissipative stochastic wave and diffusion equations resulting from an interaction of the inflaton with an environment in an external expanding homogeneous metric. We show that a diffusion equation well approximates the wave equation in a strong friction limit. We calculate the lo...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2020-06-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-020-8135-z |
| Summary: | Abstract We discuss dissipative stochastic wave and diffusion equations resulting from an interaction of the inflaton with an environment in an external expanding homogeneous metric. We show that a diffusion equation well approximates the wave equation in a strong friction limit. We calculate the long wave power spectrum of the wave equation under the assumption that the perturbations are slowly varying in time and the expansion is almost exponential. Under the assumption that the noise has a form invariant under the coordinate transformations we obtain the power spectrum close to the scale invariant one. In the diffusion approximation we go beyond the slow variation assumption. We calculate the power spectrum exactly in models with exponential inflation and polynomial potentials and with power-law inflation and exponential potentials. |
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| ISSN: | 1434-6044 1434-6052 |