Advanced physics object concepts: Glossary

All CMS simulations must be corrected so that algorithm performance matches in data and simulation.

Efficiencies are measured in data using physics knowledge to isolate groups of common objects, such as Z boson tag-and-probe.

Efficiencies in simulation can also be measured using particle truth information.

Scale factors are ratios of efficiency in data to efficiency in simulation, and are applied using event weights.

All scale factor corrections carry either rate or shape uncertainties.

Rochester corrections are used to scale the muon momentum so that simulation better matches data.

Tagging algorithms separate heavy flavor jets from jets produced by the hadronization of light quarks and gluons

Tagging algorithms produce a disriminator value for each jet that represents the likelihood that the jet came from a b hadron

Each tagging algorithm has recommended ‘working points’ (discriminator values) based on a misidentification probability for light-flavor jets

Jet energy corrections are factorized and account for many mismeasurement effects

L1+L2+L3 should be applied to jets used for analyses, with residual corrections for data

Jet energy resolution in simulation is typically too narrow and is smeared using scale factors

Jet energy and resolution corrections are sources of systematic error and uncertainties should be evaluated

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Muon corrections are a precision adjustment to a dimuon mass histogram.

B tagging scale factors and uncertainties should be considered for any distribution that relies on b-tagged jets

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In general, the jet corrections are significant and lower the momenta of the jets with standard LHC pileup conditions.

For most jets, the JEC uncertainty dominates over the JER uncertainty.

In the endcap region of the detector, the JER uncertainty in larger and matches the JEC uncertainty.