ESTIMATE OF JET ACTIVITY IN T(T)OVER-BAR EVENTS

We present a calculation of jet activity associated with pair producti on of top quarks at hadron colliders and supercolliders. Our approach is based upon a merger of 2 --> 3 matrix elements with initial and fin al state parton showers. We tabulate expected multijet rates in t (t) over bar events, and compare with O(alpha(s)(3)) matrix element result s and parton showers based upon 2 --> 2 subprocesses. The merged calcu lation includes the correct matrix element for the first leg of the pa rton shower, but also includes the effects of approximate all-orders q uark and gluon emission. We also evaluate expected jet activity in top pair events at hadron supercolliders; in particular, a comparison of the jet activity in the far forward region is made. It is found that t he merged calculation yields more jet activity in the forward region t han pure matrix element estimates, and also more jet activity in the c entral region. This can be important for background calculations to H --> WW and strong WW scattering processes.