The highest energy cosmic rays and new particle physics

Abstract

It has been argued that the observations of cosmic particles with energies in excess of 10 8 TeV represent a puzzle. Its solution requires new astrophysics or new particle physics. We show that the latter is unlikely given that the scale associated with a new particle physics threshold must be of order 1 GeV, not TeV and above, in order to resolve the problem. In most cases such new physics should have been revealed by accelerator experiments. We examine the possibility that the highest energy cosmic rays are initiated by non-standard interactions of neutrinos in the atmosphere. We show that proposals in this direction either violate s-wave unitarity or fall short of producing a sizeable effect by several orders of magnitude.

Neutrino interactions at ultrahigh energies

“…Doncheski and Robinett [45] have investigated leptoquark excitation. Bordes and collaborators [46] have speculated that new interactions might dramatically increase the UHE νN cross sections, but Burdman, Halzen, and Gandhi have countered [47] that unitarity limits the growth of the UHE cross section.…”

Cosmic neutrinos and new physics beyond the electroweak scale

“…For the lowest partial wave contribution to the cross section of a point-like particle, this new physics would violate unitarity [1]. However, two major possibilities have been discussed in the literature for which unitarity bounds need not be violated.…”

Strongly Interacting Neutrinos and the Highest Energy Cosmic Rays

“…In a recent article, however, Burdman, Halzen and Gandhi ref. [8] conclude that none of the explanations offered in the literature is a convincing one.…”

“…Second, due to the fact that we used a sharp (Θ function) threshold to turn on the strong interaction, the resulting amplitude violated unitarity, cf. [8].…”