diff --git a/Shower/SplittingFunctions/SplittingFunction.h b/Shower/SplittingFunctions/SplittingFunction.h --- a/Shower/SplittingFunctions/SplittingFunction.h +++ b/Shower/SplittingFunctions/SplittingFunction.h @@ -1,372 +1,377 @@ // -*- C++ -*- // // SplittingFunction.h is a part of Herwig - A multi-purpose Monte Carlo event generator // Copyright (C) 2002-2011 The Herwig Collaboration // // Herwig is licenced under version 2 of the GPL, see COPYING for details. // Please respect the MCnet academic guidelines, see GUIDELINES for details. // #ifndef HERWIG_SplittingFunction_H #define HERWIG_SplittingFunction_H // // This is the declaration of the SplittingFunction class. // #include "ThePEG/Interface/Interfaced.h" #include "Herwig/Shower/ShowerConfig.h" #include "ThePEG/EventRecord/RhoDMatrix.h" #include "Herwig/Decay/DecayMatrixElement.h" #include "Herwig/Shower/Base/ShowerKinematics.fh" #include "ThePEG/EventRecord/ColourLine.h" #include "ThePEG/PDT/ParticleData.h" #include "SplittingFunction.fh" namespace Herwig { using namespace ThePEG; /** \ingroup Shower * Enum to define the possible types of colour structure which can occur in * the branching. */ enum ColourStructure {Undefined=0, TripletTripletOctet = 1,OctetOctetOctet =2, OctetTripletTriplet = 3,TripletOctetTriplet=4, SextetSextetOctet = 5, ChargedChargedNeutral=-1,ChargedNeutralCharged=-2, NeutralChargedCharged=-3,EW=-4}; /** \ingroup Shower * * This is an abstract class which defines the common interface * for all \f$1\to2\f$ splitting functions, for both initial-state * and final-state radiation. * * The SplittingFunction class contains a number of purely virtual members * which must be implemented in the inheriting classes. The class also stores * the interaction type of the spltting function. * * The inheriting classes need to specific the splitting function * \f$P(z,2p_j\cdot p_k)\f$, in terms of the energy fraction \f$z\f$ and * the evolution scale. In order to allow the splitting functions to be used * with different choices of evolution functions the scale is given by * \f[2p_j\cdot p_k=(p_j+p_k)^2-m_{jk}^2=Q^2-(p_j+p_k)^2=z(1-z)\tilde{q}^2= * \frac{p_T^2}{z(1-z)}-m_{jk}^2+\frac{m_j^2}{z}+\frac{m_k^2}{1-z},\f] * where \f$Q^2\f$ is the virtuality of the branching particle, * $p_T$ is the relative transverse momentum of the branching products and * \f$\tilde{q}^2\f$ is the angular variable described in hep-ph/0310083. * * In addition an overestimate of the * splitting function, \f$P_{\rm over}(z)\f$ which only depends upon \f$z\f$, * the integral, inverse of the integral for this overestimate and * ratio of the true splitting function to the overestimate must be provided * as they are necessary for the veto alogrithm used to implement the evolution. * * @see \ref SplittingFunctionInterfaces "The interfaces" * defined for SplittingFunction. */ class SplittingFunction: public Interfaced { public: /** * The default constructor. * @param b All splitting functions must have an interaction order */ SplittingFunction(unsigned int b) : Interfaced(), _interactionType(ShowerInteraction::UNDEFINED), _interactionOrder(b), _colourStructure(Undefined), _colourFactor(-1.), angularOrdered_(true) {} public: /** * Methods to return the interaction type and order for the splitting function */ //@{ /** * Return the type of the interaction */ ShowerInteraction::Type interactionType() const {return _interactionType;} /** * Return the order of the splitting function in the interaction */ unsigned int interactionOrder() const {return _interactionOrder;} /** * Return the colour structure */ ColourStructure colourStructure() const {return _colourStructure;} /** * Return the colour factor */ double colourFactor(const IdList &ids) const { if(_colourStructure>0) return _colourFactor; else if(_colourStructure<0) { if(_colourStructure==ChargedChargedNeutral || _colourStructure==ChargedNeutralCharged) { return sqr(double(ids[0]->iCharge())/3.); } - else { + else if(_colourStructure==NeutralChargedCharged) { return sqr(double(ids[1]->iCharge())/3.); } + else if(_colourStructure==EW) { + return 1.; + } + else + assert(false); } else assert(false); } //@} /** * Purely virtual method which should determine whether this splitting * function can be used for a given set of particles. * @param ids The PDG codes for the particles in the splitting. */ virtual bool accept(const IdList & ids) const = 0; /** * Method to check the colours are correct */ virtual bool checkColours(const IdList & ids) const; /** * Methods to return the splitting function. */ //@{ /** * Purely virtual method which should return the exact value of the splitting function, * \f$P\f$ evaluated in terms of the energy fraction, \f$z\f$, and the evolution scale \f$\tilde{q}^2\f$. * @param z The energy fraction. * @param t The scale \f$t=2p_j\cdot p_k\f$. * @param ids The PDG codes for the particles in the splitting. * @param mass Whether or not to include the mass dependent terms * @param rho The spin density matrix */ virtual double P(const double z, const Energy2 t, const IdList & ids, const bool mass, const RhoDMatrix & rho) const = 0; /** * Purely virtual method which should return * an overestimate of the splitting function, * \f$P_{\rm over}\f$ such that the result \f$P_{\rm over}\geq P\f$. This function * should be simple enough that it does not depend on the evolution scale. * @param z The energy fraction. * @param ids The PDG codes for the particles in the splitting. */ virtual double overestimateP(const double z, const IdList & ids) const = 0; /** * Purely virtual method which should return * the ratio of the splitting function to the overestimate, i.e. * \f$P(z,\tilde{q}^2)/P_{\rm over}(z)\f$. * @param z The energy fraction. * @param t The scale \f$t=2p_j\cdot p_k\f$. * @param ids The PDG codes for the particles in the splitting. * @param mass Whether or not to include the mass dependent terms * @param rho The spin density matrix */ virtual double ratioP(const double z, const Energy2 t, const IdList & ids, const bool mass, const RhoDMatrix & rho) const = 0; /** * Purely virtual method which should return the indefinite integral of the * overestimated splitting function, \f$P_{\rm over}\f$. * @param z The energy fraction. * @param ids The PDG codes for the particles in the splitting. * @param PDFfactor Which additional factor to include for the PDF * 0 is no additional factor, * 1 is \f$1/z\f$, 2 is \f$1/(1-z)\f$ and 3 is \f$1/z/(1-z)\f$ * */ virtual double integOverP(const double z, const IdList & ids, unsigned int PDFfactor=0) const = 0; /** * Purely virtual method which should return the inverse of the * indefinite integral of the * overestimated splitting function, \f$P_{\rm over}\f$ which is used to * generate the value of \f$z\f$. * @param r Value of the splitting function to be inverted * @param ids The PDG codes for the particles in the splitting. * @param PDFfactor Which additional factor to include for the PDF * 0 is no additional factor, * 1 is \f$1/z\f$, 2 is \f$1/(1-z)\f$ and 3 is \f$1/z/(1-z)\f$ */ virtual double invIntegOverP(const double r, const IdList & ids, unsigned int PDFfactor=0) const = 0; //@} /** * Purely virtual method which should make the proper colour connection * between the emitting parent and the branching products. * @param parent The parent for the branching * @param first The first branching product * @param second The second branching product * @param partnerType The type of evolution partner * @param back Whether this is foward or backward evolution. */ virtual void colourConnection(tShowerParticlePtr parent, tShowerParticlePtr first, tShowerParticlePtr second, ShowerPartnerType::Type partnerType, const bool back) const; /** * Method to calculate the azimuthal angle for forward evolution * @param z The energy fraction * @param t The scale \f$t=2p_j\cdot p_k\f$. * @param ids The PDG codes for the particles in the splitting. * @param The azimuthal angle, \f$\phi\f$. * @return The weight */ virtual vector<pair<int,Complex> > generatePhiForward(const double z, const Energy2 t, const IdList & ids, const RhoDMatrix &) = 0; /** * Method to calculate the azimuthal angle for backward evolution * @param z The energy fraction * @param t The scale \f$t=2p_j\cdot p_k\f$. * @param ids The PDG codes for the particles in the splitting. * @return The weight */ virtual vector<pair<int,Complex> > generatePhiBackward(const double z, const Energy2 t, const IdList & ids, const RhoDMatrix &) = 0; /** * Calculate the matrix element for the splitting * @param z The energy fraction * @param t The scale \f$t=2p_j\cdot p_k\f$. * @param ids The PDG codes for the particles in the splitting. * @param phi The azimuthal angle, \f$\phi\f$. * @param timeLike Whether timelike or spacelike, affects inclusive of mass terms */ virtual DecayMEPtr matrixElement(const double z, const Energy2 t, const IdList & ids, const double phi, bool timeLike) = 0; /** * Whether or not the interaction is angular ordered */ bool angularOrdered() const {return angularOrdered_;} /** * Functions to state scales after branching happens */ //@{ /** * Sort out scales for final-state emission */ void evaluateFinalStateScales(ShowerPartnerType::Type type, Energy scale, double z, tShowerParticlePtr parent, tShowerParticlePtr first, tShowerParticlePtr second); /** * Sort out scales for initial-state emission */ void evaluateInitialStateScales(ShowerPartnerType::Type type, Energy scale, double z, tShowerParticlePtr parent, tShowerParticlePtr first, tShowerParticlePtr second); /** * Sort out scales for decay emission */ void evaluateDecayScales(ShowerPartnerType::Type type, Energy scale, double z, tShowerParticlePtr parent, tShowerParticlePtr first, tShowerParticlePtr second); //@} public: /** @name Functions used by the persistent I/O system. */ //@{ /** * Function used to write out object persistently. * @param os the persistent output stream written to. */ void persistentOutput(PersistentOStream & os) const; /** * Function used to read in object persistently. * @param is the persistent input stream read from. * @param version the version number of the object when written. */ void persistentInput(PersistentIStream & is, int version); //@} /** * The standard Init function used to initialize the interfaces. * Called exactly once for each class by the class description system * before the main function starts or * when this class is dynamically loaded. */ static void Init(); protected: /** @name Standard Interfaced functions. */ //@{ /** * Initialize this object after the setup phase before saving an * EventGenerator to disk. * @throws InitException if object could not be initialized properly. */ virtual void doinit(); //@} protected: /** * Set the colour factor */ void colourFactor(double in) {_colourFactor=in;} private: /** * The assignment operator is private and must never be called. * In fact, it should not even be implemented. */ SplittingFunction & operator=(const SplittingFunction &); private: /** * The interaction type for the splitting function. */ ShowerInteraction::Type _interactionType; /** * The order of the splitting function in the coupling */ unsigned int _interactionOrder; /** * The colour structure */ ColourStructure _colourStructure; /** * The colour factor */ double _colourFactor; /** * Whether or not this interaction is angular-ordered */ bool angularOrdered_; }; } #endif /* HERWIG_SplittingFunction_H */