Cosmic structure formation in a flavoured U$\left(1\right)$ dark sector at small scales

TL;DR

This paper explores how a secluded dark sector with a U(1) gauge symmetry influences small-scale cosmic structure formation, proposing a TeV-scale dark fermion model with an MeV-scale interaction that addresses small-scale issues.

Contribution

It introduces a novel dark sector model with a U(1) gauge symmetry and demonstrates its viability in solving small-scale structure formation problems.

Findings

A single dark fermion generation with TeV mass resolves small-scale issues.

Multiple fermion generations provide flexible parameter choices and remain cosmologically consistent.

The model aligns with the universe's cosmological history while addressing structure formation challenges.

Abstract

In this work we study the footprint of a secluded dark sector with a U$\left(1\right)$ gauge symmetry on the formation of cosmic structure at small scales. A single generation of dark fermions with mass in the TeV range is able to elegantly solve all small-scale issues of structure formation, while still being consistent with the cosmological history of the universe. A new interaction at the MeV scale is introduced for this purpose. As a generalization we consider multiple generations of fermions as well and show that such extensions are also cosmologically viable and allow a more flexible choice of the parameters of the theory.