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 ThePEG  2.2.1
ThePEG::Amplitude Class Referenceabstract

The Amplitude class is the abstract base class for all the classes representing complex amplitudes associated with either a hard 2 N subprocess or a decay 1 N process. More...

#include <Amplitude.h>

Inheritance diagram for ThePEG::Amplitude:

## Public Member Functions

Amplitudeoperator= (const Amplitude &)=delete
Private and non-existent assignment operator.

Public Member Functions inherited from ThePEG::HandlerBaseT< UseRandom >
double rnd () const
Return a simple flat random number in the range ]0,1[.

double rnd (double xu) const
Return a simple flat random number in the range ]0,xu[.

double rnd (double xl, double xu) const
Return a simple flat random number in the range ]xl,xu[.

bool rndbool () const
Return true with 50% probability.

bool rndbool (double p) const
Return a true with probability p.

bool rndbool (double p1, double p2) const
Return a true with probability p1/(p1+p2).

int rndsign (double p1, double p2, double p3) const
Return -1, 0, or 1 with relative probabilities p1, p2, p3.

int rnd2 (double p0, double p1) const
Return an integer with probability p /(p0+p1).

int rnd3 (double p0, double p1, double p2) const
Return an integer with probability p /(p0+p1+p2).

int rnd4 (double p0, double p1, double p2, double p3) const
Return an integer/ with probability p (p0+p1+p2+p3).

long irnd (long xu=2) const
Return a simple flat random integrer number in the range [0,xu[.

long irnd (long xl, long xu) const
Return a simple flat random integrer number in the range [xl,xu[.

const StandardModelBaseSM () const
Return a reference to the object containing the standard model parameters for this run.

tSMPtr standardModel () const
Return a pointer to the object containing the standard model parameters for this run.

virtual ~HandlerBaseT ()
Destructor.

Public Member Functions inherited from ThePEG::Interfaced
virtual ~Interfaced ()
Empty virtual destructor.

virtual bool defaultInit ()
Functions which are to be used during the actual event generation, after the setup is complete. More...

PPtr getParticle (PID) const
Create a new Particle instance given a id number.

PDPtr getParticleData (PID) const
Return a pointer to the ParticleData object corresponding to the given id number.

bool used () const
Returns true if this object has actally been used.

void useMe () const
Should be called to indicate that this object has actually been used.

tEGPtr generator () const
Return a pointer to the EventGenerator controlling the run. More...

void persistentOutput (PersistentOStream &os) const
Function used to write out object persistently. More...

void persistentInput (PersistentIStream &is, int version)
Function used to read in object persistently. More...

Public Member Functions inherited from ThePEG::InterfacedBase
virtual ~InterfacedBase ()
The virtual (empty) destructor;.

string fullName () const
Returns the full name of this object including its path, e.g. More...

string name () const
Returns the name of this object, without the path.

string path () const
Returns the path to this object including the trailing '/'. More...

string comment () const
Returns a comment assigned to this object.

void setup (istream &is)
Read setup info from a standard istream is. More...

virtual IBPtr fullclone () const
Return a full clone of this object possibly doing things to the clone to make it sane.

virtual void debugme () const
Print out debugging information for this object on std::cerr. More...

void update ()
Calls the doupdate() function with recursion prevention.

void init ()
Calls the doinit() function with recursion prevention.

virtual bool preInitialize () const
Return true if this object needs to be initialized before all other objects (except those for which this function also returns true). More...

void initrun ()
Calls the doinitrun() function with recursion prevention.

void finish ()
Calls the dofinish() function with recursion prevention.

void touch ()
This function should be called every time something in this object has changed in a way that a sanity check with update() is needed.

void reset ()
Set the state of this object to uninitialized.

void clear ()
Calls reset() and unTouch().

InitState state () const
Return the state of initialization of this object.

bool locked () const
Return true if the BaseRepository is not allowed to change the state of this object.

bool touched () const
Return true if the state of this object has been changed since the last call to update().

void persistentOutput (PersistentOStream &os) const
Function used to write out object persistently. More...

void persistentInput (PersistentIStream &is, int version)
Function used to read in object persistently. More...

Public Member Functions inherited from ThePEG::Base
virtual ~Base ()
The virtual destructor.

void debug () const
Print out debugging information for this object on std::cerr. More...

Public Member Functions inherited from ThePEG::Pointer::ReferenceCounted
CounterType referenceCount () const
Return the reference count.

Public Member Functions inherited from ThePEG::Named
Named (const string &newName=string())
Constructor with name.

Named (const Named &)=default
Explicit default copy-constructor (too avoid compiler warnings)

const string & name () const
Return name.

bool operator== (const Named &other) const
Test for equality.

bool operator< (const Named &other) const
Lexicographical comparison.

## Static Public Member Functions

static void Init ()
Standard Init function used to initialize the interfaces.

Static Public Member Functions inherited from ThePEG::HandlerBase
static void Init ()
Standard Init function used to initialize the interface.

Static Public Member Functions inherited from ThePEG::Interfaced
static void Init ()
Standard Init function.

Static Public Member Functions inherited from ThePEG::InterfacedBase
static void Init ()
Standard Init function.

Static Public Member Functions inherited from ThePEG::Base
static void Init ()
The standard Init function used to initialize the interfaces. More...

## Static Public Attributes

static AbstractNoPIOClassDescription< AmplitudeinitAmplitude
Describe an abstract base class with persistent data.

## Private Member Functions

Main virtual functions to be overridden by sub-classes.
virtual Complex value (const tcPDVector &particles, const vector< Lorentz5Momentum > &momenta, const vector< int > &helicities)=0
Return the amplitude. More...

virtual Complex overestimateValue (const tcPDVector &particles, const vector< Lorentz5Momentum > &momenta, const vector< int > &helicities)
Return an overestimated amplitude. More...

Alternative interface to main virtual functions.
Complex value (const PVector &particles, const vector< int > &helicities)
Return the amplitude. More...

Complex overestimateValue (const PVector &particles, const vector< int > &helicities)
Return an overestimated amplitude. More...

Public Types inherited from ThePEG::InterfacedBase
enum  InitState { initializing = -1, uninitialized = 0, initialized = 1, runready = 2 }
Enumeration reflecting the state of an InterfacedBase object. More...

Public Types inherited from ThePEG::Pointer::ReferenceCounted
typedef unsigned int CounterType
The integer type used for counting.

Public Attributes inherited from ThePEG::Pointer::ReferenceCounted
const unsigned long uniqueId
The unique ID. More...

Protected Member Functions inherited from ThePEG::Interfaced
void reporeg (IBPtr object, string name) const
Register the given object in the Repository with the given name in a subdirectory with the same name as this object. More...

template<typename PtrT >
bool setDefaultReference (PtrT &ptr, string classname, string objectname)
If the pointer, ptr, to an object is not set, create an object of class classname and register it with the Repository with the given objectname in a sib-directory with the same name as this object.

Interfaced ()
Protected default constructor.

Interfaced (const string &newName)
Protected constructor taking a name as argument.

Interfaced (const Interfaced &i)
Protected copy-constructor.

void setGenerator (tEGPtr generator)
Protected function to reset the generator pointer, required for automatic decayer generation in Herwig++ BSM models.

Protected Member Functions inherited from ThePEG::InterfacedBase
virtual IBPtr clone () const =0
Return a simple clone of this object. More...

InterfacedBase ()
Protected default constructor.

InterfacedBase (string newName)
Protected constructor with the name given as argument.

InterfacedBase (const InterfacedBase &i)
Protected copy-constructor.

Read setup info from a standard istream is. More...

virtual void doupdate ()
Check sanity of the object during the setup phase. More...

virtual void doinit ()
Initialize this object after the setup phase before saving an EventGenerator to disk. More...

virtual void doinitrun ()
Initialize this object. More...

virtual void dofinish ()
Finalize this object. More...

virtual IVector getReferences ()
Return a vector of all pointers to Interfaced objects used in this object. More...

virtual void rebind (const TranslationMap &)
Rebind pointer to other Interfaced objects. More...

Protected Member Functions inherited from ThePEG::Pointer::ReferenceCounted
ReferenceCounted ()
Default constructor.

ReferenceCounted (const ReferenceCounted &)
Copy-constructor.

ReferenceCountedoperator= (const ReferenceCounted &)
Assignment.

Protected Member Functions inherited from ThePEG::Named
const Namedoperator= (const Named &other)
Assignment.

const string & name (const string &newName)
Set new name.

Static Protected Member Functions inherited from ThePEG::Interfaced
static void registerRepository (IBPtr)
Register an Interfaced object with the Repository.

static void registerRepository (IBPtr, string newName)
Register an Interfaced object with the Repository, giving it a name.

## Detailed Description

The Amplitude class is the abstract base class for all the classes representing complex amplitudes associated with either a hard 2 N subprocess or a decay 1 N process.

The returned value should be dimensionless suitable scaled by the total invariant mass squared (shat), which is always computable from the specified momenta of the particles in the vertex. Notice that the amplitude for splitting 1 N processes is instead represented in other classes (derived from the SplitFun class).

The interfaces defined for Amplitude.

Definition at line 34 of file Amplitude.h.

## ◆ overestimateValue() [1/2]

 virtual Complex ThePEG::Amplitude::overestimateValue ( const tcPDVector & particles, const vector< Lorentz5Momentum > & momenta, const vector< int > & helicities )
privatevirtual

Return an overestimated amplitude.

Same as value(const tcPDVector &, const vector<Lorentz5Momentum> &, const vector<int> &), but it provides an overestimate of the complex amplitude, that is: abs( overestimaValue() ) >= abs(value())  The default definition just returns value(), but it can be overriden by derived classes.

## ◆ overestimateValue() [2/2]

 Complex ThePEG::Amplitude::overestimateValue ( const PVector & particles, const vector< int > & helicities )
private

Return an overestimated amplitude.

Calls overestimateValue(const tcPDVector &, const vector<Lorentz5Momentum> &, const vector<int> &)

## ◆ value() [1/2]

 virtual Complex ThePEG::Amplitude::value ( const tcPDVector & particles, const vector< Lorentz5Momentum > & momenta, const vector< int > & helicities )
privatepure virtual

Return the amplitude.

Given the ParticleData objects in particles, their momenta and helicities of all the particles in the vertex, return the complex amplitude. The convention is the order of the vectors is that first there is the incoming particle(s) and then the outgoing ones. For the helicities, the convention is to number them starting from 0 (no negative values, because they are used as vector indeces), for example, for a massive particle of spin S, 0 <= helicity <= 2*S. The returned value should be dimensionless suitable scaled by the total invariant mass squared ( ), which is always computable from the specified momenta of the particles in the vertex.

## ◆ value() [2/2]

 Complex ThePEG::Amplitude::value ( const PVector & particles, const vector< int > & helicities )
private

Return the amplitude.

Calls value(const tcPDVector &, const vector<Lorentz5Momentum> &, const vector<int> &) and should not be overridden.

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