# Ultra High Energy Cosmic Rays: Origin, Composition and Spectrum

## TL;DR

This paper reviews the current understanding of ultra high energy cosmic rays, covering experimental findings, theoretical models, and secondary particle emissions like neutrinos and gamma rays, to elucidate their origins and composition.

## Contribution

It provides a comprehensive overview of recent experimental data and theoretical approaches to explain the spectra, composition, and sources of ultra high energy cosmic rays.

## Key findings

- Latest experimental results on cosmic ray spectra and composition
- Theoretical models explaining cosmic ray origins
- Predictions of secondary neutrino and gamma ray emissions

## Abstract

The physics of Ultra High Energy Cosmic Rays will be reviewed, discussing the latest experimental results and theoretical models aiming at explaining the observations in terms of spectra, mass composition and possible sources. It will be also discussed the emission of secondary particles such as neutrinos and gamma rays produced by the interaction of Ultra High Energy Cosmic Rays with astrophysical photon backgrounds.