# Viable scalar spectral tilt and tensor-to-scalar ratio in near-matter bounces

## TL;DR

This paper extends a matter bounce cosmological model to include a second parameter, enabling it to produce near-matter bounces with scalar spectral tilt and tensor-to-scalar ratio consistent with Planck observations, through numerical analysis.

## Contribution

The paper introduces a modified matter bounce model with an additional parameter, allowing for realistic spectral tilt and tensor-to-scalar ratio predictions.

## Key findings

- Model achieves near-matter bounce with realistic spectral tilt.
- Numerical calculations match Planck CMB anisotropy data.
- Small tensor-to-scalar ratio consistent with observations.

## Abstract

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. For a suitable value of the parameter, the model had led to strictly scale invariant power spectra with a COBE normalized scalar amplitude and a rather small tensor-to-scalar ratio. In this work, we extend the model to achieve near-matter bounces, which contain a second parameter apart from the bounce scale. 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. For appropriate values of the additional parameter, we find that the model produces red spectra with a scalar spectral tilt and a small tensor-to-scalar ratio which are consistent with the recent observations of the anisotropies in the cosmic microwave background by Planck.