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By Unknown User (jonas.heinze)

Cosmogenic neutrinos challenge the proton dip model

The origin and composition of ultra-high-energy cosmic rays (UHECRs) remain a mystery. The proton dip model describes the shape of the cosmic ray spectrum above 10^9 GeV by the effect of a pure proton spectrum propagating through the cosmic microwave background. In these interactions secondary neutrinos are produced, which peak around 10^9 GeV.
We fit the recent UHECR spectrum measurements from the Telescope Array experiment under the assumption of pure proton composition, as assumed by the proton dip model.
We present a a full scan of the three main physical model parameters of UHECR-injection: source redshift evolution, injected maximal  proton energy and spectral power-law index. We discuss how the result  qualitatively changes compared to earlier two-parameter fits in the literature: a mild preference for a maximal energy cutoff at the sources  instead of the Greisen*Zatsepin*Kuzmin (GZK) cutoff, hard injection  spectra, and strong source evolution.
We show that the predicted neutrino flux exceeds the IceCube limit  for any parameter combination. As a result, the proton dip model is  challenged at more than 95% C.L. This is strong evidence against the dip-model independent of mass composition measurements.

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