Instrumental Backgrounds to t t-bar and Single Top Production at Hadron Colliders

A number of backgrounds to top-quark production at the LHC and Tevatron experiments are characterized as instrumental: beam related-backgrounds, cosmic ray backgrounds, and backgrounds from non-prompt (or fake) leptons. A number of strategies have been deployed in the experiments to minimize these backgrounds and to estimate their rates. The strategies are applied at the level of the accelerator, the detector apparatus, the first few cuts which are common to many physics analyses, and more refined kinematic cuts. Remaining fake lepton background is estimated using sophisticated data-driven techniques. We present here a survey of the state-of-the-art in the reduction of instrumental backgrounds and also their estimation