Cosmic ray knee and new physics at the TeV scale

Understand

We analyze the possibility that the cosmic ray knee appears at an energy threshold where the proton-dark matter cross section becomes large due to new TeV physics.

• It has been shown that such interactions could break the proton and produce a diffuse gamma ray flux consistent with MILAGRO observations.
• We argue that this hypothesis implies knees that scale with the atomic mass for the different nuclei, as KASKADE data seem to indicate.
• We find that to explain the change in the spectral index in the flux from E^{-2.7} to E^{-3.1} the cross section must grow like E^{0.4+\beta} above the knee, where \beta=0.3-0.6 parametrizes the energy dependence of the age (\tau \propto E^{-\beta}) of the cosmic rays reaching the Earth.