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Theorists and phenomenologists have contributed significantly to the development of the field of ultrahigh energy cosmic rays (UHECRs). Great progress has been achieved in modeling hadronic interactions, developing precise propagation codes, understanding the role of different backgrounds and magnetic fields in the propagation of ultrahigh energy protons and nuclei, predicting the flux of secondary neutrinos and photons, modeling astrophysical sources and their acceleration mechanisms, developing new techniques to test anisotropies in the sky distribution, proposing new physics phenomena that can be tested at ultrahigh energy, and sharpening the distinction between astrophysical interpretations of unexpected trends (such as the composition at the highest energies) and new physics at play in hadronic interactions at energies well beyond the reach of terrestrial laboratories. Better developed models when combined with recent data have framed current open questions. 1. Is the spectral feature at the highest energies the GZK cutoff or the effect of Emax? 2. Is the composition of primaries changing at the highest energies or are new interactions responsible for the change in behavior of extensive air showers? 3. At what energy and sensitivity will sources be observed? 4. At what energies cosmic rays transition from being Galactic to becoming extragalactic? And the most basic question remains, 5. what are the sources (and the acceleration mechanism) of ultrahigh energy cosmic rays? To answer these questions more observations are needed. Chief among the theorists’ wish list is the increase in statistics at the highest energies and the second wish is for full sky coverage. These efforts should lead to the localization of a source (or sources) in the sky which would revolutionize the field. Another avenue for major progress would be the detection of neutrino and photon secondaries, especially at ultrahigh energies. More immediate progress can be reached with a better establishment of an absolute energy scale which has a direct impact on many models. Another fertile area is the ongoing tests of hadronic interaction models with the LHC. More precise measurements of airshower properties may also enable the distinction between primary composition and hadronic physics effects on a wide energy range. Joint anisotropy and composition analysis between the two leading experiments (Auger and TA) would also provide a much needed consistency between the two hemispheres. This meeting marks the beginning of a great effort in this direction.

Pays tribute to David Norman Schramm, former faculty member at the University of Chicago, who died on December 19, 1997. Background information on Schramm; Career information on Schramm; Circumstances surrounding Schramm's death.

The business meeting of the Division XI Working Group on Particle Astrophysics took place in the morning of 25 August 2006, and was attended by 14 participants. [ABSTRACT FROM PUBLISHER]

We propose that higher-dimensional extended objects (p-branes) are created by super-Planckian scattering processes in theories with TeV scale gravity. As an example, we compute the cross section for p-brane creation in a (n+4)-dimensional spacetime with asymmetric compactification. We find that the cross section for the formation of a brane which is wounded on a compact submanifold of size of the fundamental gravitational scale is larger than the cross section for the creation of a spherically symmetric black hole. Therefore, we predict that branes are more likely to be created than black holes in super-Planckian scattering processes in these manifolds. The higher rate of p-brane production has important phenomenological consequences, as it significantly enhances possible detection of non-perturbative gravitational events in future hadron colliders and cosmic rays detectors. [Copyright &y& Elsevier]