Fake lepton
From Particle Wiki
Fake lepton, or fake when the context is unambiguous, is the jargon term for a misidentified lepton or a genuine lepton that is non-prompt but is identified as prompt. In publications, it is usually called a misidentified or non-prompt lepton.
In physics analysis, background arising from fake leptons is commonly estimated with partially data-driven methods. This is because Monte Carlo simulation is often not trusted to correctly model the rates and properties of fakes.
