Luis Gonzalez-Mestres
Absence of Greisen-Zatsepin-Kuzmin cutoff and stability of unstable particles
at very high energy, as a consequence of Lorentz symmetry violation
(48K, PS)
ABSTRACT. Special relativity has been tested at low energy with great accuracy,
but its extrapolation to very high-energy phenomena is much less well
established. Introducing a critical distance scale, a , below 10E-25 cm
(the wavelength scale of the highest-energy observed cosmic rays)
allows to consider models, compatible with standard tests of special
relativity, where a small violation of Lorentz symmetry (a can, for
instance, be the Planck length) produces dramatic effects on the
properties of high-energy cosmic rays. Not only the
Greisen-Zatsepin-Kuzmin (GZK) cutoff on very high-energy protons and
nuclei does no longer apply, but particles which are unstable at low
energy (neutron, several nuclei, some hadronic resonances like the
Delta++...) would become stable at very high energy. The muon would also
become stable or very long lived at very high energy if one of the two
neutrinos associated to the light charged leptons (electron, muon)
has a mass. Similar considerations apply to the tau lepton. We discuss
several possible scenarios originating these phenomena, as well as the
cosmic ray energy range (well below the energy scale associated to the
fundamental length) and experiments where they could be detected.
Observable effects are predicted for the highest-energy cosmic rays.
(Contributed paper HE 1.2.36 to the 25th International Cosmic Ray
Conference, Durban, South Africa, July 28 - August 8 , 1997)