Heavy-quark QCD exotica

Bound states of quarks

https://cds.cern.ch/record/424986/files/0001312.pdf

QCD forces and heavy quark bound states

The present knowledge of QCD confining forces between static test charges is summarised, with an emphasis on lattice results. Recent developments in relating QCD potentials to quarkonium properties by use of effective field theory methods are presented. The validity of non-relativistic QCD and the adiabatic approximation with respect to heavy quark bound states is explored. Besides the static potential and relativistic correction terms, the spectra of glueballs and gluinoballs, hybrid excitations of the QCD flux tube between fundamental colour sources, potentials between charges in various representations of the SU(3) gauge group, and multi-particle interactions are discussed. Some implications for quarkonia systems and quark-gluon hybrid mesons are drawn.

We discuss the generalized eigenvalue problem for computing energies and matrix elements in lattice gauge theory, including effective theories such as HQET. It is analyzed how the extracted effective energies and matrix elements converge when the time separations are made large. This suggests a particularly efficient application of the method for which we can prove that corrections vanish asymptotically as exp(−(EN+1 − En) t). The gap EN+1 − En can be made large by increasing the number N of interpolating fields in the correlation matrix. We also show how excited state matrix elements can be extracted such that contaminations from all other states disappear exponentially in time. As a demonstration we present numerical results for the extraction of ground state and excited B-meson masses and decay constants in static approximation and to order 1/mb in HQET.

/pdf/on-the-generalized-eigenvalue-method-for-energies-and-matrix-1fny7wp7ip.pdf

L.A. Griffiths

Papers

Mesons with excited glue

Mesons with excited glue from SU(3) lattice gauge theory

The adjoint source potential