Symmetries, Dark Matter and Minicharged Particles

TL;DR

This thesis explores new and known symmetries in particle physics to propose models for dark matter, including minicharged particles, and discusses their cosmological implications and experimental constraints.

Contribution

It introduces new symmetry-based models for dark matter, especially minicharged particles, and analyzes their cosmological and experimental implications within the Standard Model framework.

Findings

Minicharged particles can arise from symmetry breaking.

Constraints on sterile neutrino-like particles as dark matter.

A proposed solution to the EMC effect using dark matter candidates.

Abstract

This theoretical particle physics thesis is an investigation into old and new symmetries of Nature. Known symmetries and conservation laws serve as a guide for dark and visible sector model building. New symmetries of Nature are proposed, broken and subsequently reinstated at high temperatures in order to discover well-motivated particle physics models for cosmological observations implying the existence of a dark sector. Candidate processes for creation of a non-primordial matter/antimatter asymmetry result from out of equilibrium spontaneous breaking of these symmetries in the early Universe. Using the Standard Model of particle physics as a foundation with minimal new degrees of freedom, minicharged and millicharged particles emerge from a proposed spontaneous breaking of known symmetries. Experimental predictions and constraints for such dark matter candidates are given briefly here and outlined for future work. Constraints on neutrino-like particles found in the debris of broken local (gauge) symmetries are given, a subset of which are sterile and appear to be viable particle dark matter candidates. A failed baryonic dark matter candidate became a candidate to solve an outstanding nuclear structure problem, the EMC effect.