C2CR

High Energy Interactions: From Colliders to Cosmic Rays

 Partecipanti

Mappa

 Word cloud

Esplora la "nuvola delle parole (Word Cloud) per avere un'idea di massima del progetto.

 Obiettivo del progetto (Objective)

'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.'

Introduzione (Teaser)

For some time, scientists have been interested in discovering and describing what underlies hadronic interactions. One way of doing this was to use the Monte Carlo (MC) model - until now.

Descrizione progetto (Article)

In particle physics, quarks are basic components of matter, elementary particles that when forced together form hadrons. These are strongly interacting composite particles that can be divided into two groups: baryons (consisting of three quarks) and mesons (consisting of one quark and one antiquark).

The Monte Carlo model is a class of computational algorithms relying on repeated random sampling to compute results. However, existing models are not adequate and there is a need to develop a truly universal simulation for describing data in ultra-high energy cosmic ray (UHECR) experiments. Work is this area aims to determine the primary type and energy stored by force fields and particles pulled together into a new physical state.

Improving current interaction models is important for studies of hadronic interactions so that knowledge generated can be applied in collider experiments, such as those being conducted at the Pierre Auger Observatory in Argentina and CERN's Large Hadron Collider (LHC) at the French-Swiss border. The first was built to uncover the sources of ultra-high energy cosmic rays and the second was designed to test the Standard Model of particle physics, a theory of nuclear interactions that 'oversee' the dynamics of known subatomic particles.

The 'High energy interactions: from colliders to cosmic rays (C2CR)' project was devoted to the development of a new Monte Carlo (MC) model of hadronic and nuclear interactions. Researchers developed a procedure for assessing the contributions and relative importance of existing classes of enhanced diagrams and graphs. They demonstrated that certain diagrams provide important contributions and cannot be neglected in relevant studies.

C2CR members kept this in mind in attempts to develop a MC procedure for generating hadronic final state topologies. The resulting algorithm was implemented in the new version of the QGSJET MC model, the QGSJET-II.

The model has been applied for calculating the development of the extensive air shower (EAS), an outpouring of ionised particles and electromagnetic radiation that comes about when a cosmic ray of extraterrestrial origin enters the atmosphere. The predicted EAS characteristics were compared to experimental data and the consequences for nuclear composition of ultra-high energy cosmic rays (UHECRs) were inferred.

Through its inclusion in the EAS simulations programmes CONEX and Corsika, the model has been made available for public use in the cosmic ray field. The QGSJET-II model is also applicable for studies of EAS induced by very high-energy photons and for collider studies of photonuclear processes. The model has already been used for studying various astrophysical problems as related to UHECR physics.

Offering the means with which to describe experimental data on hadronic production processes, this new C2CR MC model provided a new tool for analysing data obtained in cosmic ray and collider physics experiments.