Discovery Mass Reach for Topgluons Decaying to tt̄ at the Tevatron

In topcolor assisted technicolor, topgluons are massive gluons which couple mainly to top and bottom quarks. We estimate the mass reach for topgluons decaying to tt̄ at the Tevatron as a function of integrated luminosity. The mass reach for topgluons decreases with increasing topgluon width, and is 1.0− 1.1 TeV for Run II (2 fb) and 1.3− 1.4 TeV for TeV33 (30 fb). I. TOPCOLOR AND TOPGLUONS Topcolor assisted technicolor [1] is a model of dynamical electroweak symmetry breaking in which the top quark is heavy because of a new dynamics. Topcolor replaces the SU(3)C of QCD with SU(3)1 for the third quark generation and SU(3)2 for the first two generations. The additional SU(3) symmetry produces a < tt̄ > condensate which makes the top quark heavy, and gives rise to a color octet gauge boson, the topgluon B. The topgluon is expected to be wide (Γ/M ≈ 0.3 − 0.7) and massive (M ∼ 0.5− 2 TeV). In hadron collisions it is produced through a small coupling to the first two generations, and then decays via a much larger coupling to the third generation: qq̄ → B → bb̄, tt̄. Here we estimate the mass reach for topgluons decaying to tt̄ at the Tevatron. II. SIGNAL AND BACKGROUND The sub-process cross section for qq̄ → tt̄ from both QCD and topgluons is given by [2]