Erlangen 2001 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 35: Theorie VI

HK 35.5: Vortrag

Mittwoch, 21. März 2001, 17:45–18:00, B

The Glueball Spectrum as Eigenvalue Problem — •Vera Wethkamp, Andreas Wichmann, Dieter Schütte, and Bernard Metsch — Institut für Theoretische Kernphysik der Universität Bonn, Nußallee 14-16, D-53115 Bonn, Germany

The glueball spectrum for SU(2) Yang-Mills theory is calculated via the coupled cluster method in hamiltonian lattice gauge field theory. For this method the quantum states are gauge invariant functions Ψ(U) of link variables (U ∈ SU(2)) on various spatial lattices in the infinite volume limit. Within the coupled cluster method the vacuum state ψ₀ (U) is written as ψ₀ = e^S and the eigenvalue problem of the hamiltonian is formulated as a non-linear equation for the function S(U). Glueball states are written as ψ = F e^S , yielding a linear eigenvalue problem for F. In order to expand S and F a large, but finite gauge invariant basis is constructed. This basis is built via p-fold plaquette (i.e. simplest gauge invariant quantity on the lattice) products and is truncated (to order q) by taking all states with p≤ q. Lattice translation and rotation symmetries are used to project to states with well-defined lattice spin. Numerical calculations of glueball mass ratios are presented and the approximate scale invariance is discussed.