# Scalar Field Dark Matter Spectator During Inflation: The Effect of Self-interaction

## TL;DR

This paper explores how a self-interacting scalar field dark matter spectator during inflation affects early universe conditions, using isocurvature constraints to limit model parameters.

## Contribution

It introduces a model with a self-interacting scalar dark matter spectator during inflation and constrains it with observational data.

## Key findings

- Self-interaction impacts isocurvature perturbations.
- Constraints on scalar field mass and self-coupling.
- Potential viability of dark matter candidates during inflation.

## Abstract

Nowadays cosmological inflation is the most accepted mechanism to explain the primordial seeds that led to the structure formation observed in the Universe. Current observations are in well agreement to initial adiabatic conditions, which imply that single-scalar-field inflation may be enough to describe the early Universe. However, there are several scenarios where the existence of more than a single field could be relevant during this period, for instance, the situation where the so-called spectator is present. Within the spectator scenario we can find the possibility that an ultra-light scalar field dark matter candidate could coexist with the inflaton. In this work we study this possibility where the additional scalar field could be massive or self-interacting. We use isocurvature observations to constrain the free parameters of the model.