New physics from ultrahigh energy cosmic rays

Cosmic rays from outer space enter the atmosphere with energies of up to ${10}^{11}\mathrm{GeV}$. The initial particle or a secondary hadron inside the shower may then interact with an air nucleon to produce nonstandard particles. In this article we study the production of new physics by high energy cosmic rays, focusing on the long-lived gluino of split-SUSY models and a weakly interacting massive particle (WIMP) working as dark matter. We first deduce the total flux of hadron events at any depth in the atmosphere, showing that secondary hadrons can not be neglected. Then we use these results to find the flux of gluinos and WIMPs that reach the ground after being produced inside air showers. We also evaluate the probability of producing these exotic particles in a single proton shower of ultrahigh energy. Finally we discuss the possible signal in current and projected experiments. While the tiny flux of WIMPs does not seem to have any phenomenological consequences, we show that the gluinos could modify substantially the profile of a small fraction of extensive air showers. In particular, they could produce a distinct signal observable at AUGER in showers of large zenith angle.

Figure 1

Flux of primary nucleons (solid), total nucleons, and secondary pions and kaons.

Figure 2

Interaction length in air ${\lambda }_{\tilde{G}}$ of the gluino hadron. The interaction length in water is a 3.2% shorter.

Figure 3

Total cross sections ${\sigma }_X^{hN}$ with $X=\tilde{g}\tilde{g}$ and $\chi \chi$ for $h=N$, $\pi$, $K$.

Figure 4

Flux of gluino pairs as a function of the gluino mass. We separate the contribution of the different hadrons to this flux.

Figure 5

Energy distribution of the gluino and WIMP events.

Figure 6

Probability to create $X=\tilde{g}\tilde{g}$, $\chi \chi$ by a primary nucleon (lower lines) or by the primary or any secondary hadron inside the shower (upper lines) as a function of the shower energy.

Figure 7

Distribution of the gluino pairs as a function of the shower energy.