Zero Temperature String Breaking with Staggered Quarks
  The separation of a heavy quark and antiquark pair leads to the formation of a tube of flux, or "string", which should break in the presence of light quark-antiquark pairs. This expected zero-temperature phenomenon has proven elusive in simulations of lattice QCD. In an extension of work reported last year we present clear evidence for string breaking in QCD with two flavors of dynamical staggered sea quarks and apply our results to a simple three-state mixing model for string breaking. We find that mixing is weak and falls to zero at level crossing. 
MILC Collaboration: C. Bernard (1), T. Burch (2), T.A. DeGrand (3),   C.E. DeTar (4), Steven Gottlieb (5), U.M. Heller (6), ...