Kaluza-Klein Contamination in Fermi Accelerated Environments

TL;DR

This paper proposes that Kaluza-Klein particles produced in astrophysical environments could contaminate cosmic-ray data, providing a novel way to constrain theories of new physics beyond the TeV scale using astrophysical observations.

Contribution

It introduces a method to constrain extra-dimensional models by analyzing potential KK particle contamination in cosmic-ray air shower data, extending beyond traditional collider experiments.

Findings

KK particles could constitute 10^-5 to 10^-2 of cosmic-ray events.

Astrophysical data can be used to constrain UEDs and other beyond-Standard-Model theories.

The method offers a new avenue for testing high-energy physics theories through astrophysics.

Abstract

Astrophysical constraints of new physics are often limited to weakly interacting light particles, such as axions, the Kaluza-Klein (KK) gravitons from the ADD model, sterile neutrinos and unparticles. We discuss the possibility for an astrophysical scenario to (dis)confirm new physics for heavy particles beyond TeV energy scale. In our scenario, the KK protons (the KK excited quarks/gluons within protons) within the framework of universal extra dimensions (UEDs), are produced by high energy p + p collisions in Fermi accelerated environments, with protonic isotropic spectrum d N / d E \propto E^-2 up to at least 10^18 eV. Thus, because they are also electrically charged, they should be re-accelerated by mechanism similar to normal protons. The KK states (no matter whether they have already decayed to the lightest KK particle or not) should contaminate 10^-5 to 10^-2 of cosmic-ray events for some fixed energy E (within some suitable assumptions). Hence, if we have techniques to identify them from air shower data, we can constrain UEDs scenario. Our method is an "existence proof" that we can constrain new physics beyond TeV scale or much higher by classical astrophysical scenarios, which can also be generalized to supersymmetric models, the bulk Standard Model fields within the RS model, and the endlessly emerging new models. Moreover, it can exploit domains which have no possibility to be studied in terrestrial experiments.