INTERFERENCE RADIATIVE PHENOMENA IN THE PRODUCTION OF HEAVY UNSTABLE PARTICLES

We discuss the characteristic interference phenomena, including real a s well as virtual radiative corrections, to the inclusive cross sectio ns for production of heavy unstable systems such as ttBAR or W+W- pair s. We demonstrate explicitly the (fortunate) cancellation between emis sions associated with the production of unstable particles and with th eir decays, and between emissions accompanying the decay stages. As a result the total interference effect is shown to be of O(alpha(i)GAMMA /M) or better (where alpha(i) = alpha or alpha(s) as appropriate).