JetCorrector Class Reference

Implements jet pt scale and resolution corrections. More...

#include <JetCorrector.h>

Collaboration diagram for JetCorrector:

Classes
struct	IovParams
	Auxiliary structure aggregating parameters that depent on IOV. More...
Public Member Functions
	JetCorrector (Dataset &dataset, Options const &options, TabulatedRngEngine &rngEngine)
double	GetJecFull (TLorentzVector const &rawP4, double area) const
	Computes JEC with all levels specified in the configuration applied.
double	GetJecL1 (TLorentzVector const &rawP4, double area) const
	Computes L1 JEC.
double	GetJecUncFactor (TLorentzVector const &corrP4) const
	Computes correction factor to account for JEC uncertainty.
double	GetJerFactor (TLorentzVector const &corrP4, GenJet const *genJet, double ptResultion, int rngChannel) const
	Computes correction factor to account for JER smearing.
double	GetPtResolution (TLorentzVector const &corrP4) const
	Returns relative jet pt resolution in simulation.
void	UpdateIov () const
	If needed, update IOV based on the current run.
Private Types
enum	Syst { None, JEC, JER }
	Supported types of systematic variations.
enum	SystDirection { Up, Down }
	Possible directions for systematic variations.
Private Member Functions
double	ClipFactor (double factor, double pt) const
	Clips negative or very small scaling fractors for jet momentum.
void	LoadJec () const
	Constructs an object to apply JEC using parameters of current IOV.
void	ReadIovParams (YAML::Node const config)
	Reads IOV parameters from the given node of the master configuration file.
Private Attributes
Syst	syst_
	Type of requested systematic variation.
SystDirection	systDirection_
	Direction of requested systematic variation.
std::vector< IovParams >	iovs_
	Registered IOV-dependent parameters.
double	minPtClip_
	Minimal pt to clip negative scaling factors, GeV.
IovParams const *	currentIov_
	Currently active element of iovs_.
run_t	cachedRun_
	Run seen most recently.
std::unique_ptr < FactorizedJetCorrector >	jetEnergyCorrector_
	Object to compute JEC.
std::unique_ptr < JetCorrectionUncertainty >	jecUncProvider_
	Object to provide JEC uncertainty.
std::unique_ptr < JME::JetResolution >	jerProvider_
	Object that provides pt resolution in simulation.
std::unique_ptr < JME::JetResolutionScaleFactor >	jerSFProvider_
	Object that provides data-to-simulation scale factors for jet pt resolution.
TabulatedRandomGenerator	tabulatedRng_
	Random number generator.
TTreeReaderValue< UInt_t >	run_
	Reader to access the current run.
TTreeReaderValue< float >	rho_
	Median angular pt density.

Detailed Description

Implements jet pt scale and resolution corrections.

This class computes JEC (full nominal and L1-only), JEC uncertainty, and JER smearing factors. Systematic variations are provided if requested via the syst option.

Paths to files that define JEC and JER are read from sections jets/corrections and jets/resolution of the master configuration.

Member Function Documentation

double JetCorrector::ClipFactor	(	double	factor,
		double	pt
	)			const `[private]`

Clips negative or very small scaling fractors for jet momentum.

Parameters:

`[in]`	factor	Original scaling factor.
`[in]`	pt	Jet pt to be scaled.

Returns:: Potentially clipped scaling fractor for jet momentum.

If scaling jet pt by the given original factor would produce a value below the threshold minPtClip_ (including a negative value), this method adjusts the factor to set the scaled pt equal to the threshold.

double JetCorrector::GetJecFull	(	TLorentzVector const &	rawP4,
		double	area
	)			const

Computes JEC with all levels specified in the configuration applied.

In every event, UpdateIov must be called before the first call to this method. The effect of JEC uncertainties is not included.

double JetCorrector::GetJecL1	(	TLorentzVector const &	rawP4,
		double	area
	)			const

Computes L1 JEC.

In every event, UpdateIov must be called before the first call to this method.

double JetCorrector::GetJecUncFactor ( TLorentzVector const & corrP4 ) const

Computes correction factor to account for JEC uncertainty.

Parameters:

[in] corrP4 Corrected four-momentum of a jet.

Returns:: Correction factor to rescale jet four-momentum to reproduce requested systematic variation in JEC, or 1 if no such variation has been requested.

double JetCorrector::GetJerFactor	(	TLorentzVector const &	corrP4,
		GenJet const *	genJet,
		double	ptResultion,
		int	rngChannel
	)			const

Computes correction factor to account for JER smearing.

Parameters:

`[in]`	corrP4	Corrected four-momentum of a jet.
`[in]`	genJet	Non-owning pointer to the generator-level jet matched to the given reconstructed jet. Can be nullptr if there is no match or when the stochastic smearing is desired.
`[in]`	ptResolution	Relative pt resolution as computed by GetPtResolution.
`[in]`	rngChannel	Channel to be used for the tabulated random number generator.

Returns:: Correction factor to rescale jet four-momentum.

The input four-momentum must have JEC applied. Normally, only the nominal JEC should be applied, even when a JEC variation has been requested. This is consistent with how JER smearing is applied in CMSSW.

The returned correction factor accounts for a systematic shift in JER if requested in the options. This method should only be called for simulation.

double JetCorrector::GetPtResolution ( TLorentzVector const & corrP4 ) const

Returns relative jet pt resolution in simulation.

Parameters:

[in] corrP4 Corrected four-momentum of a jet.

Returns:: Relative pt resolution.

void JetCorrector::ReadIovParams ( YAML::Node const config ) [private]

Reads IOV parameters from the given node of the master configuration file.

The given node must be a sequence of one or more nodes, each of which contains keys run_range and levels. The node run_range is a sequence of two run numbers that define the IOV; it is optional, and if missing, a catch-all IOV is constructed. The node levels is a sequence of paths to files defining different JEC levels.

void JetCorrector::UpdateIov ( ) const

If needed, update IOV based on the current run.

Must be called in every event before the first call to GetJecFull or GetJecL1.