A Search for Resonant $t\bar{t}$ Production at D\O

We report on a search for a massive particle that decays to $t\bar{t}$. The search is performed using $t\bar{t}$ candidates in the lepton+jets channel. A constrained kinematic fit, with top quark mass fixed, is used to evaluate the $t\bar{t}$ invariant mass for each candidate. We then search for deviations from the $t\bar{t}$ mass distribution predicted by QCD.