Tj. Weiler, Cosmic-ray neutrino annihilation on relic neutrinos revisited: a mechanismfor generating air showers above the Greisen-Zatsepin-Kuzmin cutoff, ASTROPART P, 11(3), 1999, pp. 303-316
If neutrinos are a significant contributor to the matter density of the uni
verse, then they should have similar to eV mass and cluster in galactic (su
per) cluster halos, and possibly in galactic halos as well. It was noted in
the early 1980's that cosmic ray neutrinos with energy within delta E/E-R
= Gamma(z)/M-z similar to 3% of the peak energy E-R = 4 (eV/m(nu)) x 10(21)
eV will annihilate on the nonrelativistic relic antineutrinos (and vice ve
rsa) to produce the Z-boson with an enhanced, resonant cross section of O(G
(F)) similar to 10(-32) cm(2). The result of the resonant neutrino annihila
tion is a hadronic Z-burst 70% of the time, which contains, on average, thi
rty photons and 2.7 nucleons with energies near or above the GZK cutoff ene
rgy of 5 x 10(19) eV. These photons and nucleons produced within our Superg
alactic halo may easily propagate to earth and initiate super-GZK air showe
rs. Here we show that the probability for each neutrino flavor at its reson
ant energy to annihilate within the halo of our Supergalactic cluster is li
kely within an order of magnitude of 1%, with the exact value depending on
unknown aspects of neutrino mixing and relic neutrino clustering. The absol
ute lower bound in a hot Big Bang universe for the probability to annihilat
e within a 50 Mpc radius (roughly a nucleon propagation distance) of earth
is 0.036%. From fragmentation data for Z-decay, we estimate that the nucleo
ns are more energetic than the photons by a factor similar to 10. Several t
ests of the hypothesis are indicated. (C) 1999 Elsevier Science B.V. All ri
ghts reserved.