Particle Candidates of Ultrahigh Energy Cosmic Rays

We discuss candidates for trans-GZK cosmic rays observed in a variety of detectors. Three types of primaries are represented among the abstracts submitted to this meeting: neutrin os causing a Z-burst, protons arising from the decay of ultra-heavy metastable particles and neutrinos within the framework of low scale string-like models of unification. We attempt to evaluate the relative merits of these schemes. No definite conclusion can be reached at this time. However, we point out that some schemes are more credible/predictive than others. Data to be gathered by the Pierre Auger observatories as well as orbiting detectors (OWL, Airwatch...) should be able to decide between the various schemes.Comment: 15 pages, LaTex. Substantially revised to take into account the discussion at HEP2001, Budapest July 200

Neutrinos in Random Magnetic Fields: The Problem of Measuring Magnetic Moments

The existence of magnetic moments of neutrinos points to physics beyond the standard model. Given current upper limits, terrestrial measurements are difficult or completely unfeasible. However, estimates of transition moments can be obtained from observation of objects such as active galactic nuclei (AGN) by means of neutrino telescopes. We describe the way of estimating the magnitudes of transition moments from such observations.Comment: LaTex, 10 pages. Uses aipproc.sty. Plenary session talk, "Beyond the Standard Model V", Balholm, Norway, 1997. (To be published in the proceedings.