Extremely high energy cosmic ray as the probe of new physics

TL;DR

This paper investigates how new physics, specifically unparticle physics, affects the propagation of extremely high energy cosmic rays, concluding that its impact is negligible at low interaction energies.

Contribution

It provides the first analysis of unparticle effects on photopion production in EXECRs, showing minimal influence at low energies.

Findings

Unparticle physics has negligible effect on EXECR interactions at low energies.

The differential cross section for unparticle exchange was computed.

New physics effects are insignificant due to low interaction energies.

Abstract

We explore the influence of new physics on extremely high energy cosmic ray (EXCER) particles. In particular, we devote our mind to one example of new physics, unparticle stuff, on one specific process that EXECRs participate in, photopion production of the EXECR nucleon with 2.7K cosmic microwave background radiation (CMBR). Through computing the differential cross section of virtual exchange of unparticle in the $p+\gamma\to p+ \pi^0$ process, we acquire the general consequence of new physics on the EXECR propagation. It is astonishing but reasonable that due to the lowness of interaction energy $\sqrt{s}$, the new physics will play a nearly negligible role in EXECR interaction.