C2CR · High Energy Interactions: From Colliders to Cosmic Rays

The years 2007 and 2008 will mark the completion of the Pierre Auger observatory and the start of the Large Hadron Collider (LHC) at CERN, respectively. Whereas the former has been built to uncover the sources of ultra-high energy cosmic rays, the latter is designed to test the Standard Model of particle physics. In both experiments, the use of Monte Carlo (MC) models to describe hadronic interactions is essential. In CR experiments, the measured properties of extensive air showers can be connected to the properties of the primary particle only via hadronic MC models. At present, the poorly known interaction models prevent a reliable determination of the primary type and its energy. Thus, an improvement of present day CR interaction models is an important and urgent task. This improvement will become possible soon, since the LHC experiments will deliver for the first time a experimental data in the kinematical region important for CR experiments. This projects aims to use these data to test and to develop further the existing QGSJET simulation. It is planed to include into QGSJET nonlinear interaction effects, to generalize the model to photo- nuclear interactions, and to account for higher twist QCD effects. Apart from its importance for a reliable extrapolation towards the very high CR energies, such a development will have an interdisciplinary aspect, opening the way for numerous applications in the collider physics. A self-consistent model like QGSJET that allows one to calculate within the same scheme total and diffractive cross sections, and to treat various hadronic final states, can be applied in collider experiments both for the general studies of hadronic interactions, and for more dedicated as, e.g., diffractive jet production. Thus the aim is to develop QGSJET to a truly universal simulation, able to describe collider data from LHC as well as to contribute to a more reliable determination of the primary type and its energy in UHECR experiments.