The primordial angular power spectrum from the alternative mass function in loop quantum cosmology

TL;DR

This paper explores how an alternative effective mass function in loop quantum cosmology influences the primordial power spectrum, revealing a new wave-packet structure sensitive to model parameters and fitting well with the standard cosmological model.

Contribution

It introduces a novel effective mass function derived from polymerization in loop quantum cosmology, showing its impact on primordial power spectrum features and angular power spectrum fitting.

Findings

Wave-packet structure appears for ξ ≥ 0.1 in the power spectrum.

Best fit to ΛCDM angular power spectrum occurs at ξ=0.2.

Primordial spectrum features depend on polymerization parameter ξ.

Abstract

We investigate the cosmological impacts of the alternative effective mass function of the modified Mukhanov-Sasaki equation in loop quantum cosmology, which is obtained from the polymerization of the classical mass function derived in the comoving gauge. This alternative effective mass function is distinct from those in the dressed metric and the hybrid approaches and is able to generate a new structure in the primordial power spectrum. After taking the Starobinsky potential and employing a particular polymerization ansatz for the inverse Hubble rate, the effective mass function is characterized by a free parameter $\xi$. When $\xi \ge 0.1$, there appears a wave-packet structure in the region preceding the almost scale invariant regime of the power spectrum and both the location and the height of the wave packet are affected by the choice of $\xi$. For the angular power spectrum, we find $\xi=0.2$ provides the best-fit curve to the result from the $\Lambda$CDM model. Our study presents a concrete example in which the fine structure of the primordial power spectrum sensitively relies on the parameters in the polymerization ansatz.