The federated Tier-2 Grid computing centre allows Austrian scientists to work with data collected by the experiments at the Large Hadron Collider (LHC) at CERN. These experiments contribute to a better understanding of the nature of matter and the universe. Not only a high level experimental setup is necessary but also requirements of the computing infrastructure for data analysis are remarkable.

The Austrian Federated Tier-2 is responsible for
  • transfering and providing data for Austrian physicists
  • computing power for investigations in high energy physics based on these data
  • simulation of events for further investigation of detectors and physical processes
  • distributed calculations within a framework of international collaborations

This computer centre consists of two computing facilities, one in Innsbruck and one in Vienna. The resources in Vienna are used for the analysis of CMS experimental data while the resources in Innsbruck are dedicated for ATLAS experimental data.

The Austrian Federated Tier-2 as a part of the WLCG (Worldwide LHC Computing Grid) is embedded in the EGEE (Enabling Grid for E-SciencE). The resources in Innsbruck are affiliated to the German GridKa cloud at the KIT (Karlsruhe Institute of Technology) while the computing centre in Vienna is associated to the Italian Tier-1 centre INFN (Istituto Nazionale di Fisica Nucleare).

Scientific background

One important goal of the LHC experiment is the discovery of the Higgs boson, a particle predicted to allow the spontaneous breaking of the electroweak gauge symmetry, and thus would explain the origin of mass. Data of previous accelerator experiments implicate a mass of 114.4 to 182 proton masses at 95% confidence level for the Higgs boson. Thus, results of the search can be expected within the next 5 years.

The Standard Model represents the current state of knowledge in particle physics. Despite the extraordinary precise predictions of this theory the standard model does not cover the whole field of physical interactions. Hence, important findings are expected at the search for new physics. One possible scenario is supersymmetry, which postulates a super partner for every standard model particle. This theory on the one hand would allow a more consistent description of nature but on the other hand supersymmetric particles might be the reason for dark matter. This dark matter is thought to be responsible for observed rotation speed of galaxies. Recent astronomic monitoring of the collisions of galaxy clusters also indicate the existence of dark matter.

An additional possible extension of the standard model description of nature is the string theory. This theory gives a consistent view of the universe including also gravity. Relative weakness of gravitation compared to other physical interactions can be explained with additional dimensions which could be seen as direct conclusion of the string theory. Unfortunately, some of the predicted effects cannot be detected directly in accelerator experiments due to the necessary high energy level. Precision measuring will allow predictions about phenomena at high energy levels, for example by extrapolation after measuring of coupling constants. But also directly observable effects are predicted at the LHC.

Investigation of heavy quarks allow a more precise measurement of the violation of CP symmetry in this field. In general, physical processes rely on a mirror symmetry which is also valid for electric charges. Some time ago it was found out that some electroweak decays surprisingly showed a violation of this symmetry to some degree. Interest in this topic of physics became evident with the award of the nobel prize to Maskawa and Kobayashi. The theory of Cabibbo-Kobayashi-Maskawa mechanism explains CP violation in the standard model. Here is an interesting connection to cosmology. Although big bang theory assumes the same amount of matter and anti-matter originally was produced, we cannot detect anti-matter in the universe at all. If we assume CP violation to be strong enough this might be a reason for the loss of anti-matter in the evolution of the universe.