# Ultra High Energy Cosmic Rays and the Highest Energies Universe

## TL;DR

This paper reviews the physics, sources, and implications of ultra high energy cosmic rays, highlighting experimental evidence, theoretical models, secondary particle production, and potential tests of new physics at the highest energies.

## Contribution

It provides a comprehensive overview of the current understanding and theoretical models of ultra high energy cosmic rays and their role in exploring the highest energy universe.

## Key findings

- Summary of experimental evidence for ultra high energy cosmic rays
- Discussion of theoretical models for their sources
- Potential tests of new physics using cosmic rays

## Abstract

We will discuss the main relevant aspects of the physics of ultra high energy cosmic rays. After a short recap of the experimental evidences, we will review theoretical models aiming at describing the sources of these extremely energetic particles opening a window on the highest energies universe. We will discuss the production of secondary particles and the possible tests of new physics that ultra high energy cosmic rays could provide.