Two knees and the Evasion of Greisen-Zatsepin-Kuz'min Cutoff in Cosmic   Ray Spectrum -- Are Neutrinos the Tachyons?
  The whole spectrum of high-energy cosmic ray (HECR) is, very likely, influenced by tachyonic neutrinos. Especially, the appearance of two knees can be fitted by the tachyon mass $m(\nu_e)=m(\nu_\mu)\simeq 0.51$ eV/$c^2$ as predicted by a minimal three - flavor model for tachyonic neutrino with one parameter $\delta=0.38$ eV only. Then the evasion of GZK cutoff could be ascribed to $Z^0(W^\pm)$-burst model together with the same mechanism for knees as well as a prediction of left-right polarization dependent lifetime asymmetry. A further conclusive experiment might be whether the protons of HECR detected on Earth are really right handed polarized? 
Guang-Jiong Ni and Zhi-Qiang Shi