ParticleListHelper Class Reference

Class to help managing creation and adding to ParticleLists. More...

#include <ParticleListHelper.h>

Public Member Functions
	ParticleListHelper ()=default
	Default constructor, does nothing.
	ParticleListHelper (const std::string &listname, bool save=true)
	Construct and initialize right away.
void	registerList (const std::string &listname, bool save=true)
	Register a list by name.
void	registerList (const DecayDescriptor &decay, bool save=true)
	Register a list using a decay descriptor.
int	getPDGCode () const
	Return the pdg code of the main list.
bool	isSelfConjugated () const
	Return whether or not this list is self conjugated.
void	create ()
	Create the list objects.
template<class ... Args>
Particle &	add (Args &&... args)
	Add a particle to the list by forwarding all arguments to the constructor of the Particle object: Any valid arguments to construct a Belle2::Particle work here.
Particle &	addParticle (const Particle &particle)
	Non-templated convenience function to add a particle from an existing particle object.
Particle &	addParticle (const ROOT::Math::PxPyPzEVector &momentum, bool conjugated=false)
	Non-templated convenience function to add a particle from simple four momentum and an indicator whether it's particle or anti particle.

Private Attributes
StoreArray< Particle >	m_particles
	Store array for the particles.
StoreObjPtr< ParticleList >	m_list
	Store object for the list.
std::optional< StoreObjPtr< ParticleList > >	m_antiList
	Optional store object for the conjugated list if that exists.
int	m_pdg
	PDG code of the list.

Detailed Description

Class to help managing creation and adding to ParticleLists.

There's a bit of management involved when trying to create a new particle list

• the list needs to be registered in the datastore
• the conjugated list needs to be registered in the datastore unless the particle is self conjugated
• the particles array needs to be registered in the datastore
• in each event the lists need to be initialized
• when adding a particle it needs to be added to the particles array and then with the index it has in the array it is added to the particle list

This class is managing all this in a clean interface

1. Add one instance as member to your class
2. in the initialize() function call registerList() with the full list name (or the DecayDescriptor)
3. in the beginning of the event() function call create()
4. Fill particles with add() or addParticle (the second one is for the benefit of python as currently ROOT has problems with variadic template functions forwarding arguments)

Definition at line 48 of file ParticleListHelper.h.

Constructor & Destructor Documentation

ParticleListHelper()

ParticleListHelper ( const std::string &  listname, bool  save = true  )

inlineexplicit

Construct and initialize right away.

Useful in cases where you create these objects directly in the initialize() function of a module

Definition at line 55 of file ParticleListHelper.h.

                                                                            : ParticleListHelper()
    {
      registerList(listname, save);
    }

Member Function Documentation

add()

Particle & add ( Args &&...  args )

inline

Add a particle to the list by forwarding all arguments to the constructor of the Particle object: Any valid arguments to construct a Belle2::Particle work here.

It will return a reference to the created particle for further modification.

Definition at line 89 of file ParticleListHelper.h.

    {
      auto index = m_particles.getEntries();
      // cppcheck doesn't seem to understand the forwarding of arguments and
      // throws an erroneous warning about reassigning appendNew
      //
      // cppcheck-suppress redundantAssignment
      // cppcheck-suppress redundantInitialization
      auto particle = m_particles.appendNew(std::forward<Args>(args)...);
      m_list->addParticle(index, particle->getPDGCode(), particle->getFlavorType());
      return *particle;
    }

addParticle() [1/2]

Particle & addParticle ( const Particle &  particle )

inline

Non-templated convenience function to add a particle from an existing particle object.

Definition at line 103 of file ParticleListHelper.h.

{ return add(particle); }

addParticle() [2/2]

Particle & addParticle ( const ROOT::Math::PxPyPzEVector &  momentum, bool  conjugated = false  )

inline

Non-templated convenience function to add a particle from simple four momentum and an indicator whether it's particle or anti particle.

Warning

particle/conjugates particle is based on what name was given when creating the list. If you created the list as 'anti-B0' than supplying 'conjugated=true' will create a 'B0'

Definition at line 110 of file ParticleListHelper.h.

    {
      return add(momentum, m_pdg * ((conjugated and not isSelfConjugated()) ? -1 : 1));
    }

getPDGCode()

int getPDGCode ( ) const

inline

Return the pdg code of the main list.

If it's not a self conjugated list there is also a list with the negative pdg value

Definition at line 77 of file ParticleListHelper.h.

{ return m_pdg; }

isSelfConjugated()

bool isSelfConjugated ( ) const

inline

Return whether or not this list is self conjugated.

Definition at line 79 of file ParticleListHelper.h.

{ return not m_antiList.has_value(); }

Member Data Documentation

m_antiList

std::optional<StoreObjPtr<ParticleList> > m_antiList

private

Optional store object for the conjugated list if that exists.

Definition at line 121 of file ParticleListHelper.h.

m_list

StoreObjPtr<ParticleList> m_list

private

Store object for the list.

Definition at line 119 of file ParticleListHelper.h.

m_particles

StoreArray<Particle> m_particles

private

Store array for the particles.

Definition at line 117 of file ParticleListHelper.h.

m_pdg

int m_pdg

private

PDG code of the list.

Definition at line 123 of file ParticleListHelper.h.

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

• analysis/DecayDescriptor/include/ParticleListHelper.h
• analysis/DecayDescriptor/src/ParticleListHelper.cc