Calculations on the lattice: The THFL (Theory Floor) section
Quantum chromodynamics (QCD) is considered a highly powerful theory for describing the strong interaction, that is, the force acting between the quarks. However, it is still a big challenge to calculate specific quantitative values from the fundamental equations of this theory, such as the masses and structural properties of mesons and baryons. The THFL (Theory Floor) section of the Helmholtz Institute Mainz develops and uses sophisticated computer simulations for this purpose.
Accelerator experiments—such as those conducted by the BESIII collaboration in Beijing, which also involves the HIM—produce and analyze exotic particles or particle states, especially mesons (particles consisting of two quarks) and baryons (systems composed of three quarks). However, whether the properties of these experimentally well-studied particles can be calculated using today’s known formulas and physical laws is an open question: Is QCD suitable for making quantitative predictions in this area? Is it understood in such depth that it can precisely explain the rich spectrum of observed particles?
To answer these questions, one needs to apply quantum chromodynamics in the low-energy range. This is extremely difficult, however, because unlike in the high-energy regime, no approximation methods can be used at low energies. The experts therefore rely on complex numerical simulations, which run exclusively on mainframe computers.
For this purpose, the HIM theorists use the method of lattice QCD, in which the continuous space-time is replaced by a discrete lattice of points. The fields of quarks and gluons then exist only at the lattice points and their connections. In this way, it becomes possible to solve the fundamental equations of QCD by computer.
Details on the HIM-Website.
Prof. Dr. Hartmut Wittig