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Rivet 4.0.0
Rivet::Sphericity Class Referenceabstract

Calculate the sphericity event shape. More...

#include <Sphericity.hh>

Inheritance diagram for Rivet::Sphericity:
Rivet::AxesDefinition Rivet::Projection Rivet::ProjectionApplier

Public Member Functions

void clear ()
 Reset the projection.
 
Vector3 mkEigenVector (Matrix3 A, const double &lambda)
 
virtual unique_ptr< Projectionclone () const =0
 Clone on the heap.
 
virtual std::string name () const
 Get the name of the projection.
 
bool valid () const
 Get the state of the projetion.
 
bool failed () const
 Get the state of the projetion.
 
void markAsOwned () const
 Mark this object as owned by a proj-handler.
 
Constructors etc.
 Sphericity (double rparam=2.0)
 Constructor.
 
 Sphericity (const FinalState &fsp, double rparam=2.0)
 
 RIVET_DEFAULT_PROJ_CLONE (Sphericity)
 Clone on the heap.
 
Access the event shapes by name
double sphericity () const
 
double transSphericity () const
 Transverse sphericity.
 
double planarity () const
 Planarity.
 
double aplanarity () const
 Aplanarity.
 
Access the sphericity basis vectors
const Vector3sphericityAxis () const
 
const Vector3sphericityMajorAxis () const
 Sphericity major axis.
 
const Vector3sphericityMinorAxis () const
 Sphericity minor axis.
 
AxesDefinition axis accessors
const Vector3axis1 () const
 
const Vector3axis2 () const
 The 2nd most significant ("major") axis.
 
const Vector3axis3 () const
 The least significant ("minor") axis.
 
Access the momentum tensor eigenvalues
double lambda1 () const
 
double lambda2 () const
 
double lambda3 () const
 
Direct methods

Ways to do the calculation directly, without engaging the caching system

void calc (const FinalState &fs)
 Manually calculate the sphericity, without engaging the caching system.
 
void calc (const Particles &particles)
 Manually calculate the sphericity, without engaging the caching system.
 
void calc (const Jets &jets)
 Manually calculate the sphericity, without engaging the caching system.
 
void calc (const vector< FourMomentum > &momenta)
 Manually calculate the sphericity, without engaging the caching system.
 
void calc (const vector< Vector3 > &momenta)
 Manually calculate the sphericity, without engaging the caching system.
 
Projection operation and comparison
bool before (const Projection &p) const
 
Projection "getting" functions
std::set< ConstProjectionPtr > getProjections () const
 Get the contained projections, including recursion.
 
std::set< ConstProjectionPtr > getImmediateChildProjections () const
 Get the contained projections, excluding recursion.
 
bool hasProjection (const std::string &name) const
 Does this applier have a projection registered under the name name?
 
template<typename PROJ >
const PROJ & getProjection (const std::string &name) const
 
const ProjectiongetProjection (const std::string &name) const
 
template<typename PROJ >
const PROJ & get (const std::string &name) const
 
template<typename PROJ >
const PROJ & getProjectionFromDeclQueue (const std::string name) const
 
Projection applying functions
template<typename PROJ = Projection>
std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > apply (const Event &evt, const Projection &proj) const
 Apply the supplied projection on event evt.
 
template<typename PROJ = Projection>
std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > apply (const Event &evt, const PROJ &proj) const
 Apply the supplied projection on event evt (user-facing alias).
 
template<typename PROJ = Projection>
std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > apply (const Event &evt, const std::string &name) const
 Apply the supplied projection on event evt (user-facing alias).
 
template<typename PROJ = Projection>
std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > apply (const std::string &name, const Event &evt) const
 Apply the supplied projection on event evt (convenience arg-reordering alias).
 

Protected Member Functions

void project (const Event &e)
 Perform the projection on the Event.
 
CmpState compare (const Projection &p) const
 Compare with other projections.
 
LoggetLog () const
 Get a Log object based on the getName() property of the calling projection object.
 
void setName (const std::string &name)
 Used by derived classes to set their name.
 
void fail ()
 Set the projection in an unvalid state.
 
Cmp< ProjectionmkNamedPCmp (const Projection &otherparent, const std::string &pname) const
 
Cmp< ProjectionmkPCmp (const Projection &otherparent, const std::string &pname) const
 
ProjectionHandlergetProjHandler () const
 Get a reference to the ProjectionHandler for this thread.
 
void setProjectionHandler (ProjectionHandler &projectionHandler) const
 
Projection registration functions
template<typename PROJ >
const PROJ & declare (const PROJ &proj, const std::string &name) const
 Register a contained projection (user-facing version)
 
template<typename PROJ >
const PROJ & declare (const std::string &name, const PROJ &proj) const
 Register a contained projection (user-facing, arg-reordered version)
 

Detailed Description

Calculate the sphericity event shape.

The sphericity tensor (or quadratic momentum tensor) is defined as

\[ S^{\alpha \beta} = \frac{\sum_i p_i^\alpha p_i^\beta}{\sum_i |\mathbf{p}_i|^2} \]

, where the Greek indices are spatial components and the Latin indices are used for sums over particles. From this, the sphericity, aplanarity and planarity can be calculated by combinations of eigenvalues.

Defining the three eigenvalues \( \lambda_1 \ge \lambda_2 \ge \lambda_3 \), with \( \lambda_1 + \lambda_2 + \lambda_3 = 1 \), the sphericity is

\[ S = \frac{3}{2} (\lambda_2 + \lambda_3) \]

The aplanarity is \( A = \frac{3}{2}\lambda_3 \) and the planarity is \( P = \frac{2}{3}(S-2A) = \lambda_2 - \lambda_3 \). The eigenvectors define a set of spatial axes comparable with the thrust axes, but more sensitive to high momentum particles due to the quadratic sensitivity of the tensor to the particle momenta.

Since the sphericity is quadratic in the particle momenta, it is not an infrared safe observable in perturbative QCD. This can be fixed by adding a regularizing power of \(r\) to the definition:

\[ S^{\alpha \beta} = \frac{\sum_i |\mathbf{p}_i|^{r-2} p_i^\alpha p_i^\beta} {\sum_i |\mathbf{p}_i|^r} \]

\(r\) is available as a constructor argument on this class and will be taken into account by the Cmp<Projection> operation, so a single analysis can use several sphericity projections with different \(r\) values without fear of a clash.

Member Function Documentation

◆ apply()

template<typename PROJ = Projection>
std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > Rivet::ProjectionApplier::apply ( const Event evt,
const Projection proj 
) const
inlineinherited

Apply the supplied projection on event evt.

Apply the supplied projection on event evt (user-facing alias).

Referenced by Rivet::ALICE::V0Trigger< MODE >::project().

◆ axis1()

const Vector3 & Rivet::Sphericity::axis1 ( ) const
inlinevirtual

Axis accessors, in decreasing order of significance. The main axis.

Implements Rivet::AxesDefinition.

◆ axis2()

const Vector3 & Rivet::Sphericity::axis2 ( ) const
inlinevirtual

The 2nd most significant ("major") axis.

Implements Rivet::AxesDefinition.

References sphericityMajorAxis().

◆ axis3()

const Vector3 & Rivet::Sphericity::axis3 ( ) const
inlinevirtual

The least significant ("minor") axis.

Implements Rivet::AxesDefinition.

References sphericityMinorAxis().

◆ before()

bool Rivet::Projection::before ( const Projection p) const
inherited

Determine whether this object should be ordered before the object p given as argument. If p is of a different class than this, the before() function of the corresponding type_info objects is used. Otherwise, if the objects are of the same class, the virtual compare(const Projection &) will be returned.

◆ calc()

void Rivet::Sphericity::calc ( const vector< Vector3 > &  momenta)

Manually calculate the sphericity, without engaging the caching system.

This one actually does the calculation

◆ clone()

virtual unique_ptr< Projection > Rivet::AxesDefinition::clone ( ) const
pure virtualinherited

Clone on the heap.

Implements Rivet::Projection.

◆ compare()

CmpState Rivet::Sphericity::compare ( const Projection p) const
protectedvirtual

Compare with other projections.

Implements Rivet::Projection.

◆ declare() [1/2]

template<typename PROJ >
const PROJ & Rivet::ProjectionApplier::declare ( const PROJ &  proj,
const std::string &  name 
) const
inlineprotectedinherited

Register a contained projection (user-facing version)

Todo:
Add SFINAE to require that PROJ inherit from Projection

Referenced by Rivet::CentralEtHCM::CentralEtHCM(), Rivet::CentralityEstimator::CentralityEstimator(), Rivet::ChargedLeptons::ChargedLeptons(), Rivet::ALICE::CLMultiplicity< INNER >::CLMultiplicity(), Rivet::DISDiffHadron::DISDiffHadron(), Rivet::DISFinalState::DISFinalState(), Rivet::DISKinematics::DISKinematics(), Rivet::DISLepton::DISLepton(), Rivet::EventMixingBase::EventMixingBase(), Rivet::GammaGammaKinematics::GammaGammaKinematics(), Rivet::GammaGammaLeptons::GammaGammaLeptons(), Rivet::GammaGammaLeptons::GammaGammaLeptons(), Rivet::GeneratedCentrality::GeneratedCentrality(), Rivet::HadronicFinalState::HadronicFinalState(), Rivet::HeavyHadrons::HeavyHadrons(), Rivet::Hemispheres::Hemispheres(), Rivet::InvisibleFinalState::InvisibleFinalState(), Rivet::LeadingParticlesFinalState::LeadingParticlesFinalState(), Rivet::LossyFinalState< FILTER >::LossyFinalState(), Rivet::LossyFinalState< FILTER >::LossyFinalState(), Rivet::MC_pPbMinBiasTrigger::MC_pPbMinBiasTrigger(), Rivet::MC_SumETFwdPbCentrality::MC_SumETFwdPbCentrality(), Rivet::ATLAS::MinBiasTrigger::MinBiasTrigger(), Rivet::MissingMomentum::MissingMomentum(), Rivet::NeutralFinalState::NeutralFinalState(), Rivet::NeutralFinalState::NeutralFinalState(), Rivet::NonHadronicFinalState::NonHadronicFinalState(), Rivet::ParisiTensor::ParisiTensor(), Rivet::PercentileProjection::PercentileProjection(), Rivet::PrimaryHadrons::PrimaryHadrons(), Rivet::PrimaryHadrons::PrimaryHadrons(), Rivet::SmearedMET::SmearedMET(), Rivet::SmearedMET::SmearedMET(), Rivet::Spherocity::Spherocity(), Rivet::ATLAS::SumET_PB_Centrality::SumET_PB_Centrality(), Rivet::ATLAS::SumET_PBPB_Centrality::SumET_PBPB_Centrality(), Rivet::TauFinder::TauFinder(), Rivet::TriggerCDFRun0Run1::TriggerCDFRun0Run1(), Rivet::TriggerCDFRun2::TriggerCDFRun2(), Rivet::UndressBeamLeptons::UndressBeamLeptons(), Rivet::ALICE::V0AndTrigger::V0AndTrigger(), Rivet::ALICE::V0Trigger< MODE >::V0Trigger(), Rivet::VetoedFinalState::VetoedFinalState(), Rivet::VisibleFinalState::VisibleFinalState(), Rivet::VisibleFinalState::VisibleFinalState(), Rivet::CentralityProjection::add(), Rivet::CentralityBinner< T, MDist >::setProjection(), and Rivet::VetoedFinalState::vetoFinalState().

◆ declare() [2/2]

template<typename PROJ >
const PROJ & Rivet::ProjectionApplier::declare ( const std::string &  name,
const PROJ &  proj 
) const
inlineprotectedinherited

Register a contained projection (user-facing, arg-reordered version)

Todo:
Add SFINAE to require that PROJ inherit from Projection

◆ get()

template<typename PROJ >
const PROJ & Rivet::ProjectionApplier::get ( const std::string &  name) const
inlineinherited

Get the named projection, specifying return type via a template argument (user-facing alias).

Todo:
Add SFINAE to require that PROJ inherit from Projection

◆ getProjection() [1/2]

template<typename PROJ >
const PROJ & Rivet::ProjectionApplier::getProjection ( const std::string &  name) const
inlineinherited

Get the named projection, specifying return type via a template argument.

Todo:
Add SFINAE to require that PROJ inherit from Projection

References Rivet::ProjectionHandler::getProjection(), and Rivet::ProjectionApplier::getProjHandler().

Referenced by Rivet::CentralityProjection::compare(), Rivet::pcmp(), Rivet::pcmp(), Rivet::pcmp(), and Rivet::pcmp().

◆ getProjection() [2/2]

const Projection & Rivet::ProjectionApplier::getProjection ( const std::string &  name) const
inlineinherited

Get the named projection (non-templated, so returns as a reference to a Projection base class).

References Rivet::ProjectionHandler::getProjection(), and Rivet::ProjectionApplier::getProjHandler().

◆ getProjectionFromDeclQueue()

template<typename PROJ >
const PROJ & Rivet::ProjectionApplier::getProjectionFromDeclQueue ( const std::string  name) const
inlineinherited

Get a named projection from this projection appliers declqueue TODO for TP: Recursion?

References MSG_ERROR.

◆ mkNamedPCmp()

◆ mkPCmp()

Cmp< Projection > Rivet::Projection::mkPCmp ( const Projection otherparent,
const std::string &  pname 
) const
protectedinherited

Shortcut to make a named Cmp<Projection> comparison with the *this object automatically passed as one of the parent projections.

Note
Alias for mkNamedPCmp

Referenced by Rivet::ALICE::PrimaryParticles::compare(), Rivet::SmearedJets::compare(), Rivet::SmearedMET::compare(), Rivet::SmearedParticles::compare(), and Rivet::Correlators::compare().

◆ name()

virtual std::string Rivet::Projection::name ( ) const
inlinevirtualinherited

◆ project()

void Rivet::Sphericity::project ( const Event e)
protectedvirtual

Perform the projection on the Event.

Implements Rivet::Projection.

◆ setProjectionHandler()

void Rivet::ProjectionApplier::setProjectionHandler ( ProjectionHandler projectionHandler) const
protectedinherited
Todo:
AB: Add Doxygen comment, follow surrounding coding style

The documentation for this class was generated from the following file:
  • /Users/chrisg/software/rivet/include/Rivet/Projections/Sphericity.hh