SINGLE-TOP-QUARK PRODUCTION BELOW T(T)OVER-BAR THRESHOLD IN E+E- COLLISIONS

A calculation of the reaction e+e- --> tbW-BAR at parton level in the Born approximation is presented in the framework of the standard model. We place emphasis on the production behaviour of the process e+e- --> tbW-BAR below the ttBAR threshold and the dependence of its cross section on the CMS energy and top-quark mass. A comparison between the single-top-quark and top-quark-pair production channel in e+e- collisions is made. We find that this process is significant for the search for the top-quark when the collider energy is less than the ttBAR threshold but sufficient to produce tbW-BAR.