FastJet
3.4.0

Class that helps perform jet background subtraction. More...
#include <fastjet/tools/Subtractor.hh>
Public Member Functions  
Subtractor (const BackgroundEstimatorBase *bge)  
define a subtractor based on a BackgroundEstimator  
Subtractor (double rho)  
define a subtractor that uses a fixed value of rho, the background pt density per unit area (which must be positive)  
Subtractor (double rho, double rho_m)  
define a subtractor that uses a fixed value of rho and rho_m; both must be >= 0;  
Subtractor ()  
default constructor  
virtual  ~Subtractor () 
default dtor  
configuring the behaviour  
void  set_defaults () 
reset all parameters to default values More...  
void  set_background_estimator (const BackgroundEstimatorBase *bge) 
void  set_use_rho_m (bool use_rho_m_in=true) 
when 'use_rho_m' is true, include in the subtraction the correction from rho_m, the purely longitudinal, particlemassinduced component of the background density per unit area More...  
bool  use_rho_m () const 
returns whether or not the rho_m component is used  
void  set_safe_mass (bool safe_mass_in=true) 
when 'safe_mass' is true, ensure that the mass of the subtracted 4vector remain positive More...  
bool  safe_mass () const 
returns whether or not safety tests on the mass are included  
void  set_known_selectors (const Selector &sel_known_vertex, const Selector &sel_leading_vertex) 
This is mostly intended for chergehadronsubtracted type of events where we wich to use vertex information to improve the subtraction. More...  
Public Member Functions inherited from fastjet::Transformer  
Transformer ()  
default ctor  
virtual  ~Transformer () 
default dtor  
Public Member Functions inherited from fastjet::FunctionOfPseudoJet< PseudoJet >  
FunctionOfPseudoJet ()  
default ctor  
virtual  ~FunctionOfPseudoJet () 
default dtor (virtual to allow safe polymorphism)  
PseudoJet  operator() (const PseudoJet &pj) const 
apply the function using the "traditional" () operator. More...  
std::vector< PseudoJet >  operator() (const std::vector< PseudoJet > &pjs) const 
apply the function on a vector of PseudoJet, returning a vector of the results. More...  
description and action  
const BackgroundEstimatorBase *  _bge 
the tool used to estimate the background if has to be mutable in case its underlying selector takes a reference jet  
double  _rho 
the fixed value of rho and/or rho_m to use if the user has selected that option  
double  _rho_m 
bool  _use_rho_m 
include the rho_m correction  
bool  _safe_mass 
ensures that the subtracted mass is +ve  
Selector  _sel_known_vertex 
selects the particles with a known vertex origin  
Selector  _sel_leading_vertex 
amongst the particles with a known vertex origin, select those coming from the leading vertex  
static const double  _invalid_rho = numeric_limits<double>::infinity() 
a value of rho that is used as a default to label that the stored rho is not valid for subtraction. More...  
static LimitedWarning  _unused_rho_m_warning 
virtual PseudoJet  result (const PseudoJet &jet) const 
returns a jet that's subtracted More...  
virtual std::string  description () const 
class description  
PseudoJet  _amount_to_subtract (const PseudoJet &jet) const 
compute the 4vector that should be subtracted from the given jet  
Additional Inherited Members  
Public Types inherited from fastjet::Transformer  
typedef PseudoJetStructureBase  StructureType 
A typedef that is needed to ensure that the PseudoJet::structure_of() template function works.  
Class that helps perform jet background subtraction.
This class derives from Transformer and makes use of a pointer to a BackgroundEstimatorBase object in order to determine the background in the vicinity of a given jet and then subtract area*background from the jet. It can also be initialised with a specific fixed value for the background pt density.
The original jet must have area support (4vector)
The underlying structure of the returned, subtracted jet (i.e. constituents, pieces, etc.) is identical to that of the original jet.
Definition at line 62 of file Subtractor.hh.
void fastjet::Subtractor::set_defaults  (  ) 
reset all parameters to default values
Note: by default, the rho_m term is not included and the safety test for the mass is not done. This is mostly for backwards compatibility with FastJet 3.0 and is highly likely to change in a future release of FastJet
Definition at line 61 of file Subtractor.cc.

inline 
when 'use_rho_m' is true, include in the subtraction the correction from rho_m, the purely longitudinal, particlemassinduced component of the background density per unit area
Note: this will be switched off by default (for backwards compatibility with FastJet 3.0) but is highly likely to change in a future release of FastJet
Definition at line 107 of file Subtractor.hh.

inline 
when 'safe_mass' is true, ensure that the mass of the subtracted 4vector remain positive
when true, if the subtracted mass is negative, we return a 4vector with 0 mass, pt and phi from the subtracted 4vector and the rapidity of the original, unsubtracted jet.
Note: this will be switched off by default (for backwards compatibility with FastJet 3.0) but is highly likely to change in a future release of FastJet
Definition at line 127 of file Subtractor.hh.

inline 
This is mostly intended for chergehadronsubtracted type of events where we wich to use vertex information to improve the subtraction.
Given the following parameters:
sel_known_vertex  selects the particles with a known vertex origin 
sel_leading_vertex  amongst the particles with a known vertex origin, select those coming from the leading vertex Momentum identified as coming from the leading vertex will be kept, momentum identified as coming from a nonleading vertex will be eliminated and a regular areamedian subtraction will be applied on the 4vector sum of the particles with unknown vertex origin. 
When this is set, we shall ensure that the pt of the subtracted 4vector is at least the pt of the particles that are known to come from the leading vertex (if it fails, subtraction returns the component that is known to come from the leading vertex — or, the original unsubtracted jet if it contains no particles from the leading vertex). Furthermore, when safe_mass() is on, we also impose a similar constraint on the mass of the subtracted 4vector (if the test fails, the longitudinal part of the subtracted 4vector is taken from the component that is known to come from the leading vertex).
Definition at line 158 of file Subtractor.hh.
returns a jet that's subtracted
jet  the jet that is to be subtracted 
Implements fastjet::Transformer.
Definition at line 72 of file Subtractor.cc.

staticprotected 
a value of rho that is used as a default to label that the stored rho is not valid for subtraction.
Definition at line 208 of file Subtractor.hh.