Implementation of the MidPoint algorithm from CDF (plugin for fastjet-v2.1 upwards) More...

#include <fastjet/CDFMidPointPlugin.hh>

Inheritance diagram for fastjet::CDFMidPointPlugin:

Collaboration diagram for fastjet::CDFMidPointPlugin:

Public Types
enum	SplitMergeScale { SM_pt, SM_Et, SM_mt, SM_pttilde }
	the choice of scale to be used in the split-merge step

Public Member Functions
	CDFMidPointPlugin (double seed_threshold_in, double cone_radius_in, double cone_area_fraction_in, int max_pair_size_in, int max_iterations_in, double overlap_threshold_in, SplitMergeScale sm_scale_in=SM_pt)
	A CDFMidPointPlugin constructor that looks like the one provided by CDF. More...

	CDFMidPointPlugin (double cone_radius_in, double overlap_threshold_in, double seed_threshold_in=1.0, double cone_area_fraction_in=1.0)
	a compact constructor More...

double	seed_threshold () const

double	cone_radius () const

double	cone_area_fraction () const

int	max_pair_size () const

int	max_iterations () const

double	overlap_threshold () const

virtual std::string	description () const
	return a textual description of the jet-definition implemented in this plugin

virtual void	run_clustering (ClusterSequence &) const
	given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence: More...

virtual double	R () const
	the plugin mechanism's standard way of accessing the jet radius

Public Member Functions inherited from fastjet::JetDefinition::Plugin
virtual bool	supports_ghosted_passive_areas () const
	return true if there is specific support for the measurement of passive areas, in the sense that areas determined from all particles below the ghost separation scale will be a passive area. More...

virtual void	set_ghost_separation_scale (double scale) const
	set the ghost separation scale for passive area determinations in future runs (strictly speaking that makes the routine a non const, so related internal info must be stored as a mutable)

virtual double	ghost_separation_scale () const

virtual bool	exclusive_sequence_meaningful () const
	if this returns false then a warning will be given whenever the user requests "exclusive" jets from the cluster sequence

virtual bool	is_spherical () const
	returns true if the plugin implements an algorithm intended for use on a spherical geometry (e.g. More...

virtual	~Plugin ()
	a destructor to be replaced if necessary in derived classes...

Detailed Description

Implementation of the MidPoint algorithm from CDF (plugin for fastjet-v2.1 upwards)

A plugin for fastjet-v2.1 that provides an interface to the CDF midpoint algorithm

CDFMidPointPlugin is a plugin for fastjet (v2.1 upwards) that provides an interface to the CDF version of Run-II iterative cone algorithm with midpoint seeds (also known as the Iterative Legacy Cone Algorithm, ILCA).

The CDF code has been taken from Joey Huston's webpage http://www.pa.msu.edu/~huston/Les_Houches_2005/Les_Houches_SM.html

Note that the CDF midpoint code contains options that go beyond those described in the Tevatron run-II document (hep-ex/0005012), notably search-cones, as described in hep-ph/0111434, and midpoints bewteen multiplets of stable cones.

Additionally, the version of the CDF midpoint code distributed here has been modified by the FastJet authors, so as to allow one to choose the scale used in the split-merge step.

Definition at line 68 of file CDFMidPointPlugin.hh.

Constructor & Destructor Documentation

fastjet::CDFMidPointPlugin::CDFMidPointPlugin	(	double	seed_threshold_in,
		double	cone_radius_in,
		double	cone_area_fraction_in,
		int	max_pair_size_in,
		int	max_iterations_in,
		double	overlap_threshold_in,
		SplitMergeScale	sm_scale_in = `SM_pt`
	)

inline

A CDFMidPointPlugin constructor that looks like the one provided by CDF.

Its arguments should have the following meaning:

seed_threshold: minimum pt for a particle to be considered a seed of the iteration.
cone_radius: standard meaning
cone_area_fraction: stable-cones are searched for with a radius Rsearch = R * sqrt(cone_area_fraction), and then expanded to size R afterwards; note (hep-ph/0610012) that this introduces IR unsafety at NLO for X+2-jet observables (where X any hard object).
max_pair_size: "midpoints" can be added between pairs of stable cones, triplets of stable cones, etc.; max_pair_size indicates the maximum number of stable cones that are assembled when adding midpoints.
max_iterations: the maximum number of iterations to carry out when looking for a stable cone.
overlap_threshold: if (overlapping_Et)/(Et_of_softer_protojet) < overlap_threshold, overlapping jets are split, otherwise they are merged.
sm_scale: a choice for the scale to be used in the split-merge step (both for ordering the momenta and quantifying the overlap); the three options are

. SM_pt: pt (default – source of small IR safety issue in purely hadronic events)

. SM_Et: Et (not boost invariant, reduces to mt at zero rapidity and to pt and infinite rapidity)

. SM_mt: transverse mass = sqrt(m^2+pt^2)

Definition at line 113 of file CDFMidPointPlugin.hh.

fastjet::CDFMidPointPlugin::CDFMidPointPlugin	(	double	cone_radius_in,
		double	overlap_threshold_in,
		double	seed_threshold_in = `1.0`,
		double	cone_area_fraction_in = `1.0`
	)

inline

a compact constructor

NB: as of version 2.4, the default value for the overlap_threshold threshold has been removed, to avoid misleading people into using the value of 0.5 without thinking, which is known to have adverse effects in high-noise environments. A recommended value is 0.75.

Definition at line 136 of file CDFMidPointPlugin.hh.

Member Function Documentation

void fastjet::CDFMidPointPlugin::run_clustering ( ClusterSequence & ) const

virtual

given a ClusterSequence that has been filled up with initial particles, the following function should fill up the rest of the ClusterSequence, using the following member functions of ClusterSequence:

plugin_do_ij_recombination(...)
plugin_do_iB_recombination(...)

Implements fastjet::JetDefinition::Plugin.

Definition at line 89 of file CDFMidPointPlugin.cc.

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

plugins/CDFCones/fastjet/CDFMidPointPlugin.hh
plugins/CDFCones/CDFMidPointPlugin.cc

Public Types

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation