class Rivet::Sphericity

Rivet::Sphericity #

Calculate the sphericity event shape. More…

#include <Sphericity.hh>

Inherits from Rivet::AxesDefinition, Rivet::Projection, Rivet::ProjectionApplier

Public Functions ##

Protected Functions ##

Additional inherited members ##

Public Functions inherited from Rivet::AxesDefinition

Public Functions inherited from Rivet::Projection

Protected Functions inherited from Rivet::Projection

Friends inherited from Rivet::Projection

Public Functions inherited from Rivet::ProjectionApplier

Detailed Description ##

class Rivet::Sphericity;

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 operation, so a single analysis can use several sphericity projections with different (r) values without fear of a clash.

Public Functions Documentation ##

function Sphericity ##

inline Sphericity(
    double rparam =2.0
)

Constructor.

function Sphericity ##

Sphericity(
    const FinalState & fsp,
    double rparam =2.0
)

function DEFAULT_RIVET_PROJ_CLONE ##

DEFAULT_RIVET_PROJ_CLONE(
    Sphericity 
)

Clone on the heap.

function clear ##

void clear()

Reset the projection.

function sphericity ##

inline double sphericity() const

Sphericity.

function transSphericity ##

inline double transSphericity() const

Transverse sphericity.

function planarity ##

inline double planarity() const

Planarity.

function aplanarity ##

inline double aplanarity() const

Aplanarity.

function sphericityAxis ##

inline const Vector3 & sphericityAxis() const

Sphericity axis.

function sphericityMajorAxis ##

inline const Vector3 & sphericityMajorAxis() const

Sphericity major axis.

function sphericityMinorAxis ##

inline const Vector3 & sphericityMinorAxis() const

Sphericity minor axis.

function axis1 ##

inline virtual const Vector3 & axis1() const

Reimplements: Rivet::AxesDefinition::axis1

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

function axis2 ##

inline virtual const Vector3 & axis2() const

The 2nd most significant (“major”) axis.

Reimplements: Rivet::AxesDefinition::axis2

function axis3 ##

inline virtual const Vector3 & axis3() const

The least significant (“minor”) axis.

Reimplements: Rivet::AxesDefinition::axis3

function lambda1 ##

inline double lambda1() const

function lambda2 ##

inline double lambda2() const

function lambda3 ##

inline double lambda3() const

function mkEigenVector ##

Vector3 mkEigenVector(
    Matrix3 A,
    const double & lambda
)

function calc ##

void calc(
    const FinalState & fs
)

Manually calculate the sphericity, without engaging the caching system.

function calc ##

void calc(
    const Particles & particles
)

Manually calculate the sphericity, without engaging the caching system.

function calc ##

void calc(
    const Jets & jets
)

Manually calculate the sphericity, without engaging the caching system.

function calc ##

void calc(
    const vector< FourMomentum > & momenta
)

Manually calculate the sphericity, without engaging the caching system.

function calc ##

void calc(
    const vector< Vector3 > & momenta
)

Manually calculate the sphericity, without engaging the caching system.

This one actually does the calculation

function name ##

inline virtual std::string name() const

Get the name of the projection.

Reimplements: Rivet::ProjectionApplier::name

function valid ##

inline bool valid() const

Get the state of the projetion.

function failed ##

inline bool failed() const

Get the state of the projetion.

function before ##

bool before(
    const Projection & p
) const

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.

function beamPairs ##

virtual const std::set< PdgIdPair > beamPairs() const

Todo: Remove the beam constraints system from projections.

Return the allowed beam pairs on which this projection can operate, not including recursion. Derived classes should ensure that all contained projections are registered in the _projections set for the beam constraint chaining to work.

function addPdgIdPair ##

inline Projection & addPdgIdPair(
    PdgId beam1,
    PdgId beam2
)

Todo: This deserves a better name!

Add a colliding beam pair.

function getProjections ##

inline std::set< ConstProjectionPtr > getProjections() const

Get the contained projections, including recursion.

function hasProjection ##

inline bool hasProjection(
    const std::string & name
) const

Does this applier have a projection registered under the name name?

function getProjection ##

template <typename PROJ >
inline const PROJ & getProjection(
    const std::string & name
) const

Todo: Add SFINAE to require that PROJ inherit from Projection

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

function getProjection ##

inline const Projection & getProjection(
    const std::string & name
) const

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

function get ##

template <typename PROJ >
inline const PROJ & get(
    const std::string & name
) const

Todo: Add SFINAE to require that PROJ inherit from Projection

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

function applyProjection ##

template <typename PROJ  =Projection>
inline std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > applyProjection(
    const Event & evt,
    const Projection & proj
) const

Deprecated:

Prefer the simpler apply<> form

Apply the supplied projection on event evt.

function applyProjection ##

template <typename PROJ  =Projection>
inline std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > applyProjection(
    const Event & evt,
    const PROJ & proj
) const

Deprecated:

Prefer the simpler apply<> form

Apply the supplied projection on event evt.

function applyProjection ##

template <typename PROJ  =Projection>
inline std::enable_if_t< std::is_base_of< Projection, PROJ >::value, const PROJ & > applyProjection(
    const Event & evt,
    const std::string & name
) const

Deprecated:

Prefer the simpler apply<> form

Apply the named projection on event evt.

function apply ##

template <typename PROJ  =Projection>
inline 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 (user-facing alias).

function apply ##

template <typename PROJ  =Projection>
inline 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).

function apply ##

template <typename PROJ  =Projection>
inline 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).

function apply ##

template <typename PROJ  =Projection>
inline 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).

function markAsOwned ##

inline void markAsOwned() const

Mark this object as owned by a proj-handler.

function clone ##

virtual unique_ptr< Projection > clone() const =0

Clone on the heap.

Reimplements: Rivet::Beam::clone

Protected Functions Documentation ##

function project ##

virtual void project(
    const Event & e
)

Perform the projection on the Event.

Reimplements: Rivet::AxesDefinition::project

function compare ##

virtual CmpState compare(
    const Projection & p
) const

Compare with other projections.

Reimplements: Rivet::AxesDefinition::compare

function getLog ##

inline Log & getLog() const

Get a Log object based on the getName() property of the calling projection object.

function setName ##

inline void setName(
    const std::string & name
)

Used by derived classes to set their name.

function fail ##

inline void fail()

Set the projection in an unvalid state.

function mkNamedPCmp ##

Cmp< Projection > mkNamedPCmp(
    const Projection & otherparent,
    const std::string & pname
) const

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

function mkPCmp ##

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

Note: Alias for mkNamedPCmp

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

function getProjHandler ##

inline ProjectionHandler & getProjHandler() const

Get a reference to the ProjectionHandler for this thread.

function declareProjection ##

template <typename PROJ >
inline const PROJ & declareProjection(
    const PROJ & proj,
    const std::string & name
)

Register a contained projection.

Todo: Add SFINAE to require that PROJ inherit from Projection

The type of the argument is used to instantiate a new projection internally: this new object is applied to events rather than the argument object. Hence you are advised to only use locally-scoped Projection objects in your Projection and Analysis constructors, and to avoid polymorphism (e.g. handling ConcreteProjection via a pointer or reference to type Projection) since this will screw up the internal type management.

function declare ##

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

Register a contained projection (user-facing version)

Todo: Add SFINAE to require that PROJ inherit from Projection

function declare ##

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

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

Todo: Add SFINAE to require that PROJ inherit from Projection

Updated on 2022-08-07 at 20:17:17 +0100