Family Matters

TL;DR

This paper reviews the structure of three families of quarks and leptons, discussing historical milestones and exploring theories that aim to explain their origin based on fundamental principles.

Contribution

It provides a non-technical overview of the development and current understanding of the family structure in particle physics, highlighting unresolved questions.

Findings

Historical milestones in family structure discovery

Overview of theories explaining family origin

Identification of fundamental principles yet to be discovered

Abstract

Quarks and leptons, the fundamental building blocks of the subatomic world, manifest in three families - replicas with identical quantum numbers that differ only in their masses. After revisiting the key milestones that led to the discovery of this peculiar structure, a non-technical overview is presented of the main attempts to explain its origin and trace it back to an as-yet-unknown fundamental principle.