# Shower formation in the presence of a string-inspired foam in space-time

## TL;DR

This paper investigates how string-inspired space-time foam models with Lorentz violation can explain cosmic photon observations without disrupting electromagnetic shower formation, aligning with gamma-ray burst data.

## Contribution

It demonstrates that certain string-inspired foam models can reconcile Lorentz violation with standard shower development, avoiding constraints from recent cosmic ray observations.

## Key findings

- Photon velocities are subluminal, explaining time delays.
- Electromagnetic showers remain intact despite Lorentz violations.
- The model naturally avoids shower formation constraints.

## Abstract

It was recently proposed that predictions of Lorentz-breaking space-time foam models from string theory may be compatible with the suggestion of light-speed variation from gamma-ray burst studies. Our analysis of foam-modified kinematics shows that despite the subluminal photon velocities explaining photon time delays one may, and in certain circumstances does, keep intact the electromagnetic showers essential for the detection and identification of cosmic photons. In contrast to other~(mostly phenomenological) approaches to Lorentz violations with modified dispersions leading to drastic changes on the formation length for the cascade development in the atmosphere and in detectors, there is the possibility that the dispersion effect in the present string foam model avoids such modifications and the theory naturally escapes the shower formation constraints from recent observations.