Lattice String Breaking and Heavy Meson Decays

We show how string breaking on the lattice, treated as a mixing effect, can be related to decay rates for heavy quark systems. We use this to make a preliminary calculation of the energy split at maximum mixing for static quarks in QCD from the decay rate for $\mathrm{{\rm Y}}(4S)\to B\bar{B}$. We extend the calculation to achieve rough estimates for the contributions of channels involving $B,B^{\ast },B_{s}and{B}_s^{\ast }$ mesons to the width of the $\mathrm{{\rm Y}}(5S)$.