Beauty physics in lattice gauge theory

We summarize the present status of lattice gauge theory computations of the leptonic decay constants fD and fB. The various sources of systematic errors are explained in a manner easily understood by the non-expert. The results obtained by the different groups are then systematically compared. As a result, we derive estimates for fD and fB in the quenched approximation through an appropriate combination of the data available from the different groups. Since we account for a possible lattice spacing dependence, the final errors are quite large. However, it is now well known how these uncertainties can be reduced. For the decay constant of heavy-light pseudoscalar mesons with masses of 1-2 GeV, an interesting comparison of a full QCD result with the corresponding simulation in the quenched approximation can be done. Effects of sea quarks of mass ms are below the statistical accuracy of these simulations. Related quantities, like B-parameters, the spectrum of beauty-hadrons and the breaking of the QCD string are discussed briefly. (orig.)