# Strong CP problem, axions, and cosmological implications of CP violation

## TL;DR

This paper reviews the strong CP problem, axions, and their cosmological implications, discussing CP violation in weak and strong interactions, axion models, and leptogenesis.

## Contribution

It provides a comprehensive pedagogical overview of CP violation, axion theories, and their relevance to cosmology, integrating recent developments and historical context.

## Key findings

- Clarifies the role of axions in solving the strong CP problem
- Highlights the cosmological significance of CP violation and axions
- Discusses the implications of Type-II leptogenesis

## Abstract

In this talk, I present a pedagogical and historical review related to the CP symmetry. It includes the weak CP violation, the strong CP problem, "invisible" axions and cosmology, and Type-II leptogenesis.