Luis Gonzalez-Mestres
Physics opportunities above the Greisen-Zatsepin-Kuzmin cutoff: Lorentz
symmetry violation at the Planck scale
(203K, PS)
ABSTRACT. Special relativity has been tested at low energy with great
accuracy, but these results cannot be extrapolated to very high-energy
phenomena: this new domain of physics may actually provide the key to
the, yet unsettled, question of the ether and the absolute rest frame.
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) leads to a deformed relativistic kinematics (DRK) producing
dramatic effects on the properties of very high-energy cosmic rays. For
instance, the Greisen-Zatsepin-Kuzmin (GZK) cutoff does no longer apply
and particles which are unstable at low energy (neutron, some hadronic
resonances like the Delta++ , possibly several nuclei...) become stable at
very high energy. In these models, an absolute local rest frame exists
(the vacuum rest frame, VRF) and special relativity is a low-momentum
limit. We discuss the possible effects of Lorentz symmetry violation (LSV)
on kinematics and dynamics, as well as the cosmic-ray energy range (well
below the energy scale associated to the fundamental length) and
experiments (on earth and from space) where they could be detected.
Invited talk at the Workshop on "Observing Giant Cosmic Ray Air Showers
for > 10E20 eV Particles from Space", Univ. of Maryland, Nov 13-15, 1997.