Reformulation of a likelihood approach to fake-lepton estimation in the framework of Bayesian inference

Abstract

Prompt isolated leptons are essential in many analyses in high-energy particle physics but are subject to fake-lepton background, i.e. objects that mimic the lepton signature. The fake-lepton background is difficult to estimate from simulation and is often directly determined from data. A popular method is the matrix method, which however suffers from several limitations. This paper recapitulates an alternative approach based on a likelihood with Poisson constraints and reformulates the problem from a different starting point in the framework of Bayesian statistics. The equality of both approaches is shown and several cases are studied in which the matrix method is limited. In addition, the fake lepton background is recalculated and compared to the estimate with the matrix method in an example top-quark measurement.

References in corpus (9)

• Simulation of truncated normal variables
• Measurement of the top quark-pair production cross section with ATLAS in pp collisions at $\sqrt{s}=7\TeV$
• Search for the Standard Model Higgs boson produced in association with top quarks and decaying into $b\bar{b}$ in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector
• Search for charged Higgs bosons decaying via $H^{\pm }\to {\tau }^{\pm }{\nu }_{\tau }$ in the $\tau$+jets and $\tau$+lepton final states with 36 fb${}^{-1}$ of $pp$ collision data recorded at $\sqrt{s}=13$ TeV with the ATLAS experiment
• Measurements of $t\bar{t}$ differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in $pp$ collisions at $\sqrt{s}=13$ TeV using the ATLAS detector
• Measurements of inclusive and differential fiducial cross-sections of $t\bar{t}\gamma$ production in leptonic final states at $\sqrt{s}$ = 13 TeV in ATLAS
• Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at $\sqrt{s}=7$ TeV
• Improving estimates of the number of fake leptons and other mis-reconstructed objects in hadron collider events: BoB's your UNCLE. (Previously "The Matrix Method Reloaded")
• A Poisson likelihood approach to fake lepton estimation with the matrix method