siscone::Csplit_merge_ptcomparison Class Reference

comparison of jets for split--merge ordering More...

#include <split_merge.h>

List of all members.

Public Member Functions
	Csplit_merge_ptcomparison ()
	default ctor
std::string	SM_scale_name () const
	return the name corresponding to the SM scale variable
bool	operator() (const Cjet &jet1, const Cjet &jet2) const
	comparison between 2 jets
void	get_difference (const Cjet &j1, const Cjet &j2, Cmomentum *v, double *pt_tilde) const
	get the difference between 2 jets, calculated such that rounding errors will not affect the result even if the two jets have almost the same content (so that the difference is below the rounding errors)
Public Attributes
std::vector< Cmomentum > *	particles
	pointer to the list of particles
std::vector< double > *	pt
	pointer to the pt of the particles
Esplit_merge_scale	split_merge_scale
	the following parameter controls the variable we're using for the split-merge process i.e.

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Detailed Description

comparison of jets for split--merge ordering

a class that allows us to carry out comparisons of pt of jets, using information from exact particle contents where necessary.

Definition at line 111 of file split_merge.h.

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Member Function Documentation

void siscone::Csplit_merge_ptcomparison::get_difference	(	const Cjet &	j1,
		const Cjet &	j2,
		Cmomentum *	v,
		double *	pt_tilde
	)		const

get the difference between 2 jets, calculated such that rounding errors will not affect the result even if the two jets have almost the same content (so that the difference is below the rounding errors)

Parameters:

j1	first jet
j2	second jet
v	jet1-jet2
pt_tilde	jet1-jet2 pt_tilde

Definition at line 177 of file split_merge.cpp.

References siscone::Cjet::contents, and siscone::Cjet::n.

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Member Data Documentation

Esplit_merge_scale siscone::Csplit_merge_ptcomparison::split_merge_scale

the following parameter controls the variable we're using for the split-merge process i.e.

the variable we use for 1. ordering jet candidates; 2. computing te overlap fraction of two candidates. The default value uses pttile (p-scheme pt). Other alternatives are pt, mt=sqrt(pt^2+m^2)=sqrt(E^2-pz^2) or Et. NOTE: Modifying the default choice can have nasty effects:

• using pt leads to some IR unsafety when we have two jets, e.g. back-to-back, with the same pt. In that case, their ordering in pt is random and can be affected by the addition of a soft particle. Hence, we highly recommand to keep this to the default value i.e. to use pt only for the purpose of investigating the IR issue
• using Et is safe but do not respect boost invariance
• using mt solves the IR unsafety issues with the pt variable for QCD jets but the IR unsafety remains for nack-to-back jets of unstable narrow-width particles (e.g. Higgs). Therefore, keeping the default value is strongly advised.

Definition at line 158 of file split_merge.h.

Referenced by SM_scale_name().

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

• siscone/split_merge.h
• siscone/split_merge.cpp