Speaker
Description
In this talk I will discuss an interesting model of the early Universe with bounce and its features. Within this model we show that the correct spectra of cosmological perturbations may be generated at early contracting epoch, with mild fine-tuning ensuring that the scalar spectral tilt and tensor-to-scalar ratio are consistent with observations. The smallness of tensor-to-scalar ratio is governed by the smallness of the scalar sound speed. Arbitrarily small values of tensor-to-scalar ratio are forbidden in our setup because of the strong coupling in the past. Nevertheless, we show that it is possible to generate perturbations in a controllable way, i.e. in the regime where the background evolution and perturbations are legitimately described within classical field theory and weakly coupled quantum theory. We also have acquired and analyzed the bispectrum of primordial scalar perturbations and the corresponding non-Gaussianities in this particular model. The found shape function of the bispectrum did not correspond to the widely used local, equilateral, orthogonal or enfolded shapes. For each separate configuration of primordial perturbation's momenta (local, equilateral, and enfolded) it is possible to satisfy the current observational bounds for non-linear parameter even under the restrictions of the applicability of regime, where the background evolution and perturbations are legitimately described within classical field theory and weakly coupled quantum theory at all times. However, one can not select the parameters of the model so that all three non-linear parameters would simultaneously satisfy the acceptable observational constraints. So, within this talk I will show the entire bounds on the model parameters and discuss the fate of this particular and other similar models.
| Тематическая секция | Гравитация и космология |
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