Strong Neutrino-Nucleon Interactions at Ultrahigh Energies as a Solution to the GZK Puzzle

Abstract

After a short review of the ultrahigh energy cosmic ray puzzle -the apparent observation of cosmic rays originating from cosmological distances with energies above the expected Greisen-Zatsepin-Kuzmin cutoff 4 × 10 19 eV -we consider strongly interacting neutrino scenarios as an especially interesting solution. We show that all features of the ultrahigh energy cosmic ray spectrum from 10 17 eV to 10 21 eV can be described to originate from a simple power-like injection spectrum of protons, under the assumption that the neutrino-nucleon cross-section is significantly enhanced at center of mass energies above ≈ 100 TeV. In such a scenario, the cosmogenic neutrinos produced during the propagation of protons through the cosmic microwave background initiate air showers in the atmosphere, just as the protons. The total air shower spectrum induced by protons and neutrinos shows excellent agreement with the observations. We shortly discuss TeVscale extensions of the Standard Model which may lead to a realization of a strongly interacting neutrino scenario. We emphasize, however, that such a scenario may even be realized within the standard electroweak model: electroweak instanton/sphaleron induced processes may get strong at ultrahigh energies. Possible tests of strongly interacting neutrino scenarios range from observations at cosmic ray facilities and neutrino telescopes to searches at lepton nucleon scattering experiments.

Extremely energetic cosmic neutrinos and their impact on particle physics and cosmology

“…Again, the upper limits onσ 0 disappear above > ∼ 100 µb. We note here in passing, that, for even higher and more speculative cross sections, > ∼ 1-10 mb, electroweak sphaleron production qualifies [58] as a particular strongly interacting neutrino scenario [32,59], according to which the mysterious EHECR beyond the predicted Greisen-Zatsepin-Kuzmin (GZK) cutoff at E GZK 4 × 10 19 eV [30,31] are initiated by cosmogenic neutrinos.…”

The Rise of High Energy Neutrino Astronomy at Horizon

“…31) The neutrino mass existence has been also motivated by old and recent solar neutrino oscillation evidences 3,24,25) and most recent claims by KamLAND 30) of anti-neutrino disappearance (all in agreement within a Large Mixing Angle neutrino model and Ám 2 $ 7 Â 10 À5 eV 2 ). In this Z-WW Showering for light neutrino mass models large fluxes of UHE are necessary 10,16,23,29,40) or higher neutrino relic density or better clustering are needed: 16,37) indeed a heaviest neutrino mass m ' 1:2-2:2 eV while still being compatible with known bounds (but marginally with more severe WMAP indirect limits), might better gravitationally cluster leading to denser dark local-galactic halos and lower neutrino fluxes. 16,37) It should remarked that in this scenario m !…”

Strongly interacting neutrinos as the highest energy cosmic rays: A quantitative analysis

“…arising through compositeness [14,15,16], through electroweak sphalerons [17,18,19,20,21,22,23,5,24], through string excitations in theories with a low string and unification scale [25,26,27], through Kaluza-Klein modes from compactified extra dimensions [28,29,30,31,32,33], or through p-brane production in models with warped extra dimensions [34,35,36], respectively (for recent reviews, see Refs. [37,38]).…”