e+e− → bbudμ−νμ with a tt production

The cross section of e+e− → bbudμ−νμ process with a complete set of tree diagrams, 232 diagrams in the unitary gauge, was calculated at the energy range of s = 340−500 GeV by using GRACE system. A main contribution to the cross section comes from tt production, where t and t decay into bud and bμ−νμ, respectively. It was found that the interference between the diagrams with tt production and those with single-t through WW pair production amounts to 10% at the tt threshold energy region. In the energy region above twice of the top quark mass, more than 95% of the cross section comes from the tt diagrams.