Background Estimator based on the median pt/area of a set of grid cells. More...

#include <fastjet/tools/GridMedianBackgroundEstimator.hh>

Inheritance diagram for fastjet::GridMedianBackgroundEstimator:

Collaboration diagram for fastjet::GridMedianBackgroundEstimator:

[legend]

Public Member Functions
constructors and destructors
	GridMedianBackgroundEstimator (double ymax, double requested_grid_spacing)

	GridMedianBackgroundEstimator (const RectangularGrid &grid)
	Constructor based on a user's fully specified RectangularGrid.

	GridMedianBackgroundEstimator (double rapmin_in, double rapmax_in, double drap_in, double dphi_in, Selector tile_selector=Selector())
	Constructor with the explicit parameters for the underlying RectangularGrid. More...

setting a new event
void	set_particles (const std::vector< PseudoJet > &particles)
	tell the background estimator that it has a new event, composed of the specified particles. More...

void	set_compute_rho_m (bool enable)
	determine whether the automatic calculation of rho_m and sigma_m is enabled (by default true)

retrieving fundamental information
double	rho () const
	returns rho, the median background density per unit area

double	sigma () const
	returns sigma, the background fluctuations per unit area; must be multipled by sqrt(area) to get fluctuations for a region of a given area. More...

double	rho (const PseudoJet &jet)
	returns rho, the background density per unit area, locally at the position of a given jet. More...

double	sigma (const PseudoJet &jet)
	returns sigma, the background fluctuations per unit area, locally at the position of a given jet. More...

bool	has_sigma ()
	returns true if this background estimator has support for determination of sigma

double	rho_m () const
	Returns rho_m, the purely longitudinal, particle-mass-induced component of the background density per unit area.

double	sigma_m () const
	returns sigma_m, a measure of the fluctuations in the purely longitudinal, particle-mass-induced component of the background density per unit area; must be multipled by sqrt(area) to get fluctuations for a region of a given area. More...

double	rho_m (const PseudoJet &jet)
	Returns rho_m locally at the jet position. As for rho(jet), it is non-const.

double	sigma_m (const PseudoJet &jet)
	Returns sigma_m locally at the jet position. As for rho(jet), it is non-const.

bool	has_rho_m () const
	Returns true if this background estimator has support for determination of rho_m. More...

double	mean_area () const
	returns the area of the grid cells (all identical, but referred to as "mean" area for uniformity with JetMedianBGE). More...

configuring the behaviour
virtual void	set_rescaling_class (const FunctionOfPseudoJet< double > *rescaling_class)
	Set a pointer to a class that calculates the rescaling factor as a function of the jet (position). More...

description
std::string	description () const
	returns a textual description of the background estimator

Public Member Functions inherited from fastjet::BackgroundEstimatorBase
virtual	~BackgroundEstimatorBase ()
	a default virtual destructor that does nothing

	BackgroundEstimatorBase ()

const FunctionOfPseudoJet< double > *	rescaling_class () const
	return the pointer to the jet density class

Public Member Functions inherited from fastjet::RectangularGrid
	RectangularGrid (double rapmax_in, double cell_size)
	ctor with simple initialisation More...

	RectangularGrid (double rapmin_in, double rapmax_in, double drap_in, double dphi_in, Selector tile_selector=Selector())
	ctor with more control over initialisation More...

	RectangularGrid ()
	dummy ctor (will give an unusable grid)

virtual int	n_tiles () const override
	returns the total number of tiles in the tiling; valid tile indices run from 0 ... More...

virtual int	n_good_tiles () const override
	returns the number of tiles that are "good"; i.e. More...

virtual int	tile_index (const PseudoJet &p) const override
	returns the index of the tile in which p is located, or -1 if p is outside the tiling region

virtual bool	tile_is_good (int itile) const override
	returns whether a given tile is good

virtual double	tile_area (int) const override
	returns the area of tile itile.

virtual double	mean_tile_area () const override
	returns the mean area of tiles.

double	rapmin () const
	returns the minimum rapidity extent of the grid

double	rapmax () const
	returns the maxmium rapidity extent of the grid

double	drap () const
	returns the spacing of the grid in rapidity

double	dphi () const
	returns the spacing of the grid in azimuth

virtual bool	is_initialised () const override
	returns true if the grid is in a suitably initialised state

Public Member Functions inherited from fastjet::TilingBase
virtual bool	all_tiles_good () const
	returns whether all tiles are good

virtual bool	all_tiles_equal_area () const
	returns true if all tiles have the same area

bool	is_initialized () const

virtual	~TilingBase ()
	virtual destructor

Additional Inherited Members
Protected Member Functions inherited from fastjet::BackgroundEstimatorBase
void	_median_and_stddev (const std::vector< double > &quantity_vector, double n_empty_jets, double &median, double &stand_dev_if_gaussian, bool do_fj2_calculation=false) const
	given a quantity in a vector (e.g. More...

double	_percentile (const std::vector< double > &sorted_quantity_vector, const double percentile, const double nempty=0.0, const bool do_fj2_calculation=false) const
	computes a percentile of a given sorted vector More...

Protected Attributes inherited from fastjet::BackgroundEstimatorBase
const FunctionOfPseudoJet< double > *	_rescaling_class

Static Protected Attributes inherited from fastjet::BackgroundEstimatorBase
static LimitedWarning	_warnings_empty_area

Detailed Description

Background Estimator based on the median pt/area of a set of grid cells.

Description of the method: This background estimator works by projecting the event onto a grid in rapidity and azimuth. In each grid cell, the scalar pt sum of the particles in the cell is computed. The background density is then estimated by the median of (scalar pt sum/cell area) for all cells.

Parameters: The class takes 2 arguments: the absolute rapidity extent of the cells and the size of the grid cells. Note that the size of the cell will be adjusted in azimuth to satisfy the 2pi periodicity and in rapidity to match the requested rapidity extent.

Rescaling: It is possible to use a rescaling profile. In this case, the profile needs to be set before setting the particles and it will be applied to each particle (i.e. not to each cell). Note also that in this case one needs to call rho(jet) instead of rho() [Without rescaling, they are identical]

Definition at line 77 of file GridMedianBackgroundEstimator.hh.

Constructor & Destructor Documentation

◆ GridMedianBackgroundEstimator() [1/2]

fastjet::GridMedianBackgroundEstimator::GridMedianBackgroundEstimator	(	double	ymax,
		double	requested_grid_spacing
	)

inline

Parameters

ymax	maximal absolute rapidity extent of the grid
requested_grid_spacing	size of the grid cell. The "real" cell size could differ due e.g. to the 2pi periodicity in azimuthal angle (size, not area)

Definition at line 92 of file GridMedianBackgroundEstimator.hh.

◆ GridMedianBackgroundEstimator() [2/2]

fastjet::GridMedianBackgroundEstimator::GridMedianBackgroundEstimator	(	double	rapmin_in,
		double	rapmax_in,
		double	drap_in,
		double	dphi_in,
		Selector	tile_selector = `Selector()`
	)

inline

Constructor with the explicit parameters for the underlying RectangularGrid.

Parameters

rapmin	the minimum rapidity extent of the grid
rapmax	the maximum rapidity extent of the grid
drap	the grid spacing in rapidity
dphi	the grid spacing in azimuth
tile_selector	optional (geometric) selector to specify which tiles are good; a tile is good if a massless 4-vector at the center of the tile passes the selection

Definition at line 117 of file GridMedianBackgroundEstimator.hh.

Member Function Documentation

◆ set_particles()

void fastjet::GridMedianBackgroundEstimator::set_particles ( const std::vector< PseudoJet > & particles )

virtual

tell the background estimator that it has a new event, composed of the specified particles.

Implements fastjet::BackgroundEstimatorBase.

Definition at line 43 of file GridMedianBackgroundEstimator.cc.

◆ sigma() [1/2]

double fastjet::GridMedianBackgroundEstimator::sigma ( ) const

virtual

returns sigma, the background fluctuations per unit area; must be multipled by sqrt(area) to get fluctuations for a region of a given area.

Reimplemented from fastjet::BackgroundEstimatorBase.

Definition at line 146 of file GridMedianBackgroundEstimator.cc.

◆ rho()

double fastjet::GridMedianBackgroundEstimator::rho ( const PseudoJet & jet )

virtual

returns rho, the background density per unit area, locally at the position of a given jet.

Note that this is not const, because a user may then wish to query other aspects of the background that could depend on the position of the jet last used for a rho(jet) determination.

Implements fastjet::BackgroundEstimatorBase.

Definition at line 157 of file GridMedianBackgroundEstimator.cc.

◆ sigma() [2/2]

double fastjet::GridMedianBackgroundEstimator::sigma ( const PseudoJet & jet )

virtual

returns sigma, the background fluctuations per unit area, locally at the position of a given jet.

As for rho(jet), it is non-const.

Reimplemented from fastjet::BackgroundEstimatorBase.

Definition at line 167 of file GridMedianBackgroundEstimator.cc.

◆ sigma_m()

double fastjet::GridMedianBackgroundEstimator::sigma_m ( ) const

virtual

returns sigma_m, a measure of the fluctuations in the purely longitudinal, particle-mass-induced component of the background density per unit area; must be multipled by sqrt(area) to get fluctuations for a region of a given area.

Reimplemented from fastjet::BackgroundEstimatorBase.

Definition at line 188 of file GridMedianBackgroundEstimator.cc.

◆ has_rho_m()

bool fastjet::GridMedianBackgroundEstimator::has_rho_m ( ) const

inlinevirtual

Returns true if this background estimator has support for determination of rho_m.

Note that support for sigma_m is automatic if one has sigma and rho_m support.

Reimplemented from fastjet::BackgroundEstimatorBase.

Definition at line 198 of file GridMedianBackgroundEstimator.hh.

◆ mean_area()

double fastjet::GridMedianBackgroundEstimator::mean_area ( ) const

inline

returns the area of the grid cells (all identical, but referred to as "mean" area for uniformity with JetMedianBGE).

Definition at line 203 of file GridMedianBackgroundEstimator.hh.

◆ set_rescaling_class()

void fastjet::GridMedianBackgroundEstimator::set_rescaling_class ( const FunctionOfPseudoJet< double > * rescaling_class )

virtual

Set a pointer to a class that calculates the rescaling factor as a function of the jet (position).

Note that the rescaling factor is used both in the determination of the "global" rho (the pt/A of each jet is divided by this factor) and when asking for a local rho (the result is multiplied by this factor).

The BackgroundRescalingYPolynomial class can be used to get a rescaling that depends just on rapidity.

Note that this has to be called BEFORE any attempt to do an actual computation

The same profile will be used for both pt and mt (this is probabaly a good approximation since the particle density changes is what dominates the rapidity profile)

Reimplemented from fastjet::BackgroundEstimatorBase.

Definition at line 252 of file GridMedianBackgroundEstimator.cc.

The documentation for this class was generated from the following files: