http://arxiv.org/abs/1812.06803
In a recent work, we had constructed a model consisting of two fields—a canonical scalar field and a non-canonical ghost field—that had sourced a symmetric matter bounce scenario. The model had involved only one parameter, viz. the scale associated with the bounce. The model had led to strictly scale invariant scalar and tensor power spectra and, for suitable values of the parameter, we had shown that the model also leads to a viable scalar amplitude and tensor-to-scalar ratio. In this work, we extend the model to achieve near-matter bounces which lead to a tilt in the power spectra. As the new model does not seem to permit analytical evaluation of the scalar modes near the bounce, with the aid of techniques which we had used in our earlier work, we compute the scalar and the tensor power spectra numerically. The new model involves an additional parameter (apart from the scale associated with the bounce) which determines the tilt of the power spectra. We find that an appropriate value for the additional parameter produces red scalar as well as tensor power spectra and a scalar spectral tilt that is consistent with the observations. Moreover, the value of the original parameter, which is fixed by the COBE normalized value of the power spectrum, leads to a very small tensor-to-scalar ratio that is consistent with the current upper bound from the observations of the anisotropies in the cosmic microwave background by Planck.
R. Raveendran and L. Sriramkumar
Tue, 18 Dec 18
90/91
Comments: 19 pages, 4 figures. arXiv admin note: text overlap with arXiv:1703.10061
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