Single lepton production at large transverse momentum

We study the production of single isolated leptons at large transverse momentum, $p_T^\ell > M_W/2$. The dominant source of such leptons is production of an on-shell $W$ boson recoiling against a hard jet. Vetoing this jet forces the $W$ boson to be produced off resonance and significantly reduces the standard model cross section, thereby enhancing the discovery prospects for non standard model physics. A significant number of events have the topologically interesting signature of a large $p_T$ lepton balancing a jet with little measured missing transverse energy.