Trilepton production at the CERN LHC: Standard model sources and beyond

Abstract

Events with three or more isolated leptons in the final state are known to be signatures of new physics phenomena at high energy collider physics facilities. Standard model sources of isolated trilepton final states include gauge boson pair production such as $WZ$ and $W{\ensuremath{\gamma}}^{*}$, and $t\overline{t}$ production. We demonstrate that leptons from heavy flavor decays, such as $b\ensuremath{\rightarrow}lX$ and $c\ensuremath{\rightarrow}lX$, provide sources of trileptons that can be orders of magnitude larger after cuts than other standard model backgrounds to new physics processes. We explain the physical reason heavy flavor backgrounds survive isolation cuts. We propose new cuts to control the backgrounds in the specific case of chargino plus neutralino pair production in supersymmetric models. After these cuts are imposed, we show that it should be possible to find at least a $4\ensuremath{\sigma}$ excess for supersymmetry parameter space point LM9 with $30\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity.