The simulation of the quantum field theory of strong interactions, Quantum Chromodynamics (QCD), has been a grand challenge in High Performance Computing (HPC) over the past 30 years [KS]. It was only recently that the hadronic spectrum could be computed with sufficient accuracy, at the expense of 1020 floating point operations on a BlueGene/P system at the Jülich Supercomputing Centre (JSC), in the highly acclaimed study by S. Dürr et al. [SD]. In this study the full quantum fluctuations of the QCD ground-state were taken into account and quarks near physical mass were used in the simulations. The determination of physical observables with the quantum numbers of the QCD vacuum, such as the pseudoscalarη’ meson or isoscalar form factors of nucleons, is an even more demanding problem of numerical QCD.
The reason is that these observables are characterized by purely gluonic intermediate states, and hence involve the computation of closed fermionic loops with appropriate operator-insertions. Based on symmetry, the numerical values of these loop diagrams are fluctuating around zero, and the physical signals that we are after come out of correlations with other diagrams. For this reason it has been so far prohibitive to achieve results with sufficient precision. However, today’s petascale computers combined with improved algorithms promise to attain sufficient statistics and hence make progress in this area of disconnected diagrams.
To achieve this goal, the current project shall create software for multi/many-core architectures such as the upcoming Cy-Τera machine at the host and the JuRoPa cluster at JSC, the number ten machine of the current TOP500 list [TOP500]. The aim is twofold: firstly to achieve at least a 25% efficiency of our QCD application which is much higher than the normal 5% and, secondly, to compute the key physical observables like the η’ mass, the isoscalar nucleon form factors and the sigma term all of which require the evaluation of disconnected diagrams. This part of our work will be embedded into the novel form of a joint Simulation Laboratory (SimLab) for Particle and Nuclear Physics between the European Petascalecenter JSC and the newly established Computation-based Science and Technology Research Center (CaSToRC) at the Cyprus Institute.
Dr Alejandro Vaquero Avilés-Casco
Tel. +357 22208608
The Project is co-financed by the European Regional Development Fund and the Republic of Cyprus through the Research Promotion Foundation.
- Acronym: Flavor Singlets
- Website: http://castorc.cyi.ac.cy/node/1367
- Center: CaSToRC
- Funding Source: Research Promotion Foundation
- CyI Funding: €167,500
- Funding Period: 36 months
- Starting Date: 03/10/11
- End Date: 02/10/14
- Coordinator: The Cyprus Institute
University of Cyprus, Forschungszentrum Jülich GmbH