Relic Neutrinos, Z-Bursts, and Cosmic Rays above 10^{20} eV
| dc.creator | Weiler, Thomas J. | |
| dc.date | 1999-10-13 | |
| dc.date.accessioned | 2026-07-07T04:08:19Z | |
| dc.date.available | 2026-07-07T04:08:19Z | |
| dc.description | The observation of cosmic--ray events above the Greisen-Kuzmin-Zatsepin (GZK) cutoff of $\sim 5\times 10^{19}$ eV challenges orthodox modeling. We discuss a possible solution which uses standard hot Big Bang cosmology and Standard Model (SM) particle physics augmented only by $\lsim $ eV neutrino masses as suggested by solar, atmospheric, and terrestrial neutrino detection. In this scheme, cosmic ray neutrinos from distant, highest-energy sources annihilate resonantly on the relic-neutrino background to produce Z-bosons. The highly-boosted ($γ_Z\sim 10^{11}$) Z's instantly decay, producing "Z-bursts" of highly-collimated jets of hadrons and photons. The burst content includes, on average, twenty photons and two nucleons with super-GZK energies. We show that the probability for each neutrino with energy within a fraction $Γ_Z/M_Z$ of the resonant value $E_R=4(eV/m_ν)\times 10^{21}$ eV to annihilate within the halo of our galactic supercluster is likely within an order of magnitude of 1%. Depending on the magnitude of the cosmic neutrino flux above 10^{20} eV, this "local" rate for primary production may be high enough to produce the cosmic ray events observed above the GZK cutoff. Several tests of this Z-burst hypothesis for generating super-GZK events are presented, including (i) a new cutoff energy at E_R; (ii) a large $γ/p$ ratio for primaries near the upper end of the spectrum; (iii) directional pairing of events, and pointing to their cosmic sources; and (iv) a neutrino flux above the GZK cutoff energy which is possibly measurable directly in proposed $\gsim 10^{11}$ ton cosmic-ray detectors. | |
| dc.description | 22 pages, 1 figure, Invited talk at "Beyond the Desert 99", Ringberg Castle, Tegernsee, Germany, June 6-12, 1999 | |
| dc.identifier | https://arxiv.org/abs/hep-ph/9910316 | |
| dc.identifier | http://arxiv.org/abs/hep-ph/9910316 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/49487 | |
| dc.subject | High Energy Physics - Phenomenology | |
| dc.subject | Astrophysics | |
| dc.title | Relic Neutrinos, Z-Bursts, and Cosmic Rays above 10^{20} eV | |
| dc.type | text |