Finite width and irreducible background effects to $t\bar{t}$ production at ${\hat{I}}^3{\hat{I}}^3$ Next Linear Colliders

Abstract

We study the complete process \phphbbww\ using exact matrix element computations at tree-level, at a $\sqrt{s}=500$ GeV \eeb\ linear collider of the next generation. Incoming photons produced via back-scattering of laser light are considered. Sizable effects due to the finite width of the top quark as well as to the irreducible background to $t\bar{t}$ production and decay are predicted.

11 pages, Latex, 4 figures uuencoded, complete ps file available via anonymous ftp at: ftp://cpt1.dur.ac.uk/pub/preprints/dtp95/dtp9556/dtp9556_text.ps and dtp9556_fig*.ps, *=1,2,3,4