CMB constraints on inflection-point inflation with a pseudo-scalar dark matter

TL;DR

This paper examines an inflection-point inflation model involving a pseudo-scalar dark matter candidate, analyzing its compatibility with CMB data and dark matter relic abundance constraints.

Contribution

It introduces a complex scalar singlet model with a pseudo-scalar inflaton and dark matter, exploring its observational viability and stability conditions.

Findings

CMB constraints limit inflationary parameters for dark matter stability

Pseudo-scalar dark matter is viable only if thermally produced

Model ensures invariance under Z3 symmetry, decoupling the imaginary part

Abstract

In this work, we investigate the physical aspects of the inflection-point inflation scenario and assess its observational viability in light of current Cosmic Microwave Background (CMB) data. The model we consider encapsulates the inflaton with a pseudo-scalar (the dark matter candidate) in a complex neutral scalar singlet. The cosmological constraints on the parameters of inflation derived at a high energy scale are translated to a low energy scale by running these parameters. Ensuring the entire Lagrangian to be invariant under a $Z_3$ symmetry with the adequate transformation of the fields, the imaginary part of the singlet decouples from the other scalars of the model. We then investigate if the observational viability of inflation is also compatible with this pseudo-scalar being the dark matter component.We show that the CMB constraints on the inflationary parameters assure that the pseudo-scalar is stable and provides the correct relic dark matter abundance only when the pseudo-scalar is thermally produced.