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MEqq2gZ2ffPowhegQED.h
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// -*- C++ -*-
#ifndef HERWIG_MEqq2gZ2ffPowhegQED_H
#define HERWIG_MEqq2gZ2ffPowhegQED_H
//
// This is the declaration of the MEqq2gZ2ffPowhegQED class.
//
#include "Herwig++/MatrixElement/HwMEBase.h"
#include "ThePEG/Helicity/Vertex/AbstractFFVVertex.h"
#include "Herwig++/MatrixElement/ProductionMatrixElement.h"
#include "Herwig++/Models/StandardModel/OneLoopFFAWZVertex.h"
namespace Herwig {
using namespace ThePEG;
/**
* The MEqq2gZ2ffPowhegQED class implements
* \f$q\bar q \to \gamma/Z^0 \to \ell^+\ell^-\f$
* including both QED and QCD corrections
*
* @see \ref MEqq2gZ2ffPowhegQEDInterfaces "The interfaces"
* defined for MEqq2gZ2ffPowhegQED.
*/
class MEqq2gZ2ffPowhegQED: public HwMEBase {
public:
/**
* Enum for the type of Dipole
*/
enum DipoleType {
II12,II21,FF34,FF43,
IF13,IF14,IF23,IF24
};
public:
/**
* The default constructor.
*/
MEqq2gZ2ffPowhegQED();
/**
* Virtual members to be overridden by inheriting classes
* which implement hard corrections
*/
//@{
/**
* Has a POWHEG style correction
*/
virtual bool hasPOWHEGCorrection() {return true;}
/**
* Apply the POWHEG style correction
*/
virtual HardTreePtr generateHardest(ShowerTreePtr,
vector<ShowerInteraction::Type> inter);
//@}
public:
/** @name Virtual functions required by the MEBase class. */
//@{
/**
* Return the scale associated with the last set phase space point.
*/
virtual Energy2 scale() const;
/**
* The number of internal degrees of freedom used in the matrix
* element.
*/
virtual int nDim() const;
/**
* Generate internal degrees of freedom given nDim() uniform
* random numbers in the interval \f$ ]0,1[ \f$. To help the phase space
* generator, the dSigHatDR should be a smooth function of these
* numbers, although this is not strictly necessary.
* @param r a pointer to the first of nDim() consecutive random numbers.
* @return true if the generation succeeded, otherwise false.
*/
virtual bool generateKinematics(const double * r);
/**
* Return the order in \f$\alpha_S\f$ in which this matrix
* element is given.
*/
virtual unsigned int orderInAlphaS() const;
/**
* Return the order in \f$\alpha_{EW}\f$ in which this matrix
* element is given.
*/
virtual unsigned int orderInAlphaEW() const;
/**
* Add all possible diagrams with the add() function.
*/
virtual void getDiagrams() const;
/**
* Get diagram selector. With the information previously supplied with the
* setKinematics method, a derived class may optionally
* override this method to weight the given diagrams with their
* (although certainly not physical) relative probabilities.
* @param dv the diagrams to be weighted.
* @return a Selector relating the given diagrams to their weights.
*/
virtual Selector<DiagramIndex> diagrams(const DiagramVector & dv) const;
/**
* Return a Selector with possible colour geometries for the selected
* diagram weighted by their relative probabilities.
* @param diag the diagram chosen.
* @return the possible colour geometries weighted by their
* relative probabilities.
*/
virtual Selector<const ColourLines *>
colourGeometries(tcDiagPtr diag) const;
/**
* Construct the vertex of spin correlations.
*/
virtual void constructVertex(tSubProPtr);
/**
* Return the matrix element squared differential in the variables
* given by the last call to generateKinematics().
*/
virtual CrossSection dSigHatDR() const;
/**
* The matrix element for the kinematical configuration
* previously provided by the last call to setKinematics(), suitably
* scaled by sHat() to give a dimension-less number.
* @return the matrix element scaled with sHat() to give a
* dimensionless number.
*/
virtual double me2() const;
//@}
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:
/**
* Virtual functions for the NLO calculation
*/
//@{
/**
* Calculate of the full next-to-leading order weight
*/
double NLOWeight() const;
/**
* The leading-order matrix element, to be implemented in the
* inheriting classes.
* @param particles The ParticleData objects of the particles
* @param momenta The momenta of the particles
* @param first Whether or not this is the first call and the spin
* and diagram information should be stored
*/
double loME(const cPDVector & particles,
const vector<Lorentz5Momentum> & momenta,
bool first=false) const;
/**
* The real matrix element divided by \f$2 g_S^2\f$, to be implemented in the
* inheriting classes.
* @param particles The ParticleData objects of the particles
* @param momenta The momenta of the particles
*/
double realQCDME(const cPDVector & particles,
const vector<Lorentz5Momentum> & momenta) const;
/**
* The real matrix element divided by \f$2 e^2\f$, to be implemented in the
* inheriting classes.
* @param particles The ParticleData objects of the particles
* @param momenta The momenta of the particles
*/
vector<double> realQEDME(const cPDVector & particles,
const vector<Lorentz5Momentum> & momenta) const;
//@}
/**
* Matrix element for \f$q\bar{q}\to \gamma/Z \to f\bar{f}\f$.
* @param fin Spinors for incoming quark
* @param ain Spinors for incoming antiquark
* @param fout Spinors for outgoing lepton
* @param aout Spinors for outgoing antilepton
* @param me Whether or not to calculate the matrix element for spin correlations
*/
double qqbarME(vector<SpinorWaveFunction> & fin ,
vector<SpinorBarWaveFunction> & ain ,
vector<SpinorBarWaveFunction> & fout,
vector<SpinorWaveFunction> & aout,
bool me) const;
/**
* Subtracted virtual contribution
*/
double subtractedVirtual() const;
/**
* Subtracted real contribution
*/
vector<double>
subtractedRealQCD(pair<double,double> x, double z,
double zJac,
double oldqPDF, double newqPDF, double newgPDF,
DipoleType dipole) const;
/**
* Subtracted real contribution
*/
vector<double>
subtractedRealQED(pair<double,double> x, double z,
double zJac,
double oldqPDF, double newqPDF, double newpPDF,
DipoleType dipole) const;
/**
* Calculate of the collinear counterterms
*/
//@{
/**
* Quark collinear counter term
*/
double collinearQuark(double x, Energy2 mu2, double jac, double z,
double oldPDF, double newPDF) const;
/**
* Gluon or photon collinear counter term
*/
double collinearBoson(Energy2 mu2, double jac, double z,
double oldPDF, double newPDF) const;
/**
* Quark collinear counter term (needed for PDF in the DIS scheme)
*/
double collinearQuarkKDIS(double x, double jac, double z,
double oldPDF, double newPDF) const;
/**
* Gluon or photon collinear counter term (needed for PDF in the DIS scheme)
*/
double collinearBosonKDIS(double jac, double z,
double oldPDF, double newPDF) const;
/**
* Quark collinear counter term (IF piece, for QED)
*/
double collinearQuarkIF(double x, double jac, double z,
double oldPDF, double newPDF) const;
//@}
/**
* Dipole subtracted matrix elements
*/
//@{
/**
* \f$q\bar q\f$
*/
pair<double,double>
subtractedQCDMEqqbar(const vector<Lorentz5Momentum> & pnew,
DipoleType dipole, bool subtract) const;
/**
* \f$g\bar q\f$
*/
pair<double,double>
subtractedQCDMEgqbar(const vector<Lorentz5Momentum> & pnew,
DipoleType dipole, bool subtract) const;
/**
* \f$q\bar q\f$
*/
pair<double,double>
subtractedQEDMEqqbar(const vector<Lorentz5Momentum> & pnew,
DipoleType dipole, bool subtract) const;
/**
* \f$g\bar q\f$
*/
pair<double,double>
subtractedQEDMEpqbar(const vector<Lorentz5Momentum> & pnew,
DipoleType dipole, bool subtract) const;
/**
* The supression function
*/
pair<double,double> supressionFunction(Energy2 pt2) const {
switch( supressionFunction_ ) {
case 0:
return make_pair(1.,0.);
case 1:
if(pt2 < lambda2_ ) return make_pair(1.,0.);
else return make_pair(0.,1.);
case 2:
return make_pair(lambda2_/(pt2+lambda2_),pt2/(pt2+lambda2_));
default:
assert(false);
}
}
/**
* Generate a hard QCD emission
*/
void hardQCDEmission(vector<ShowerProgenitorPtr> & particlesToShower,
int & emission_type, Energy & pTmax);
/**
* Generate a hard QED emission
*/
void hardQEDEmission(vector<ShowerProgenitorPtr> & particlesToShower,
int & emission_type, Energy & pTmax);
/**
* Generate a hard initial-initial QED radiation
*/
void hardQEDIIEmission(vector<ShowerProgenitorPtr> & particlesToShower,
int & emission_type, Energy & pTmax);
/**
* Generate a hard initial-final QED radiation
*/
void hardQEDIFEmission(vector<ShowerProgenitorPtr> & particlesToShower,
int & emission_type, Energy & pTmax);
/**
* Generate a hard final-final QED radiation
*/
void hardQEDFFEmission(vector<ShowerProgenitorPtr> & particlesToShower,
int & emission_type, Energy & pTmax);
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
virtual IBPtr clone() const;
/** Make a clone of this object, possibly modifying the cloned object
* to make it sane.
* @return a pointer to the new object.
*/
virtual IBPtr fullclone() const;
//@}
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();
/**
* Initialize this object. Called in the run phase just before
* a run begins.
*/
virtual void doinitrun();
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a class with persistent data.
*/
static ClassDescription<MEqq2gZ2ffPowhegQED> initMEqq2gZ2ffPowhegQED;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
MEqq2gZ2ffPowhegQED & operator=(const MEqq2gZ2ffPowhegQED &);
private:
/**
* Kinematic variables for the real radiation
*/
//@{
/**
* First variable
*/
mutable double zTilde_;
/**
* Second variable
*/
mutable double vTilde_;
/**
* Azimuthal angle
*/
mutable double phi_;
//@}
/**
* Which corrections to included
*/
unsigned int corrections_;
/**
* Which QED terms to include
*/
unsigned int QEDContributions_;
/**
* Include incoming photons?
*/
bool incomingPhotons_;
/**
* Whether to generate the positive, negative or leading order contribution
*/
unsigned int contrib_;
/**
* Power for sampling \f$x_p\f$
*/
double power_;
/**
* Phase-space sampling for z
*/
double zPow_;
/**
* Phase-space sampling for y
*/
double yPow_;
/**
* Pointer to the gluon ParticleData object
*/
tcPDPtr gluon_;
/**
* Factor for \f$C_F\f$ dependent pieces
*/
mutable double CFfact_;
/**
* Factor for \f$T_R\f$ dependent pieces
*/
mutable double TRfact_;
/**
* Factor for EM pieces
*/
mutable double EMfact_;
/**
* Strong coupling
*/
mutable double alphaS_;
/**
* EM coupling
*/
mutable double alphaEM_;
/**
* Use a fixed value of couplings
*/
bool fixedCouplings_;
/**
* Leading-order matrix element
*/
mutable double loME_;
/**
* Structure for the virtual FS QED corrections
*/
mutable double f2term_;
/**
* EW correction
*/
mutable double EWterm_;
/**
* Choice of the supression function
*/
unsigned int supressionFunction_;
/**
* Scalar for the supression function
*/
Energy2 lambda2_;
/**
* Storage of the weights of the different processes for the hard emission
* generation
*/
mutable vector<double> weights_;
private:
/**
* Momenta of the particles for gluon emmision from first the particle
*/
mutable vector<Lorentz5Momentum> realEmissionQCDGluon1_;
/**
* Momenta of the particles for anti quark emission from the first particle
*/
mutable vector<Lorentz5Momentum> realEmissionQCDQuark1_;
/**
* Momenta of the particle for gluon emission from the second particle
*/
mutable vector<Lorentz5Momentum> realEmissionQCDGluon2_;
/**
* Momenta of the particles for quark emission from the second particle
*/
mutable vector<Lorentz5Momentum> realEmissionQCDQuark2_;
/**
* Momenta of the particles for gluon emmision from first the particle
*/
mutable vector<Lorentz5Momentum> realEmissionQEDPhoton1_;
/**
* Momenta of the particles for anti quark emission from the first particle
*/
mutable vector<Lorentz5Momentum> realEmissionQEDQuark1_;
/**
* Momenta of the particle for gluon emission from the second particle
*/
mutable vector<Lorentz5Momentum> realEmissionQEDPhoton2_;
/**
* Momenta of the particles for quark emission from the second particle
*/
mutable vector<Lorentz5Momentum> realEmissionQEDQuark2_;
/**
* Momenta of the particles for photon emission from the lepton
*/
mutable vector<Lorentz5Momentum> realEmissionQEDFFLepton3_;
/**
* Momenta of the particles for photon emission from the antilepton
*/
mutable vector<Lorentz5Momentum> realEmissionQEDFFLepton4_;
/**
* Momenta of the particles for photon emission from 13 dipole
*/
mutable vector<Lorentz5Momentum> realEmissionQEDIF13_;
/**
* Momenta of the particles for photon emission from 23 dipole
*/
mutable vector<Lorentz5Momentum> realEmissionQEDIF23_;
/**
* Momenta of the particles for photon emission from 14 dipole
*/
mutable vector<Lorentz5Momentum> realEmissionQEDIF14_;
/**
* Momenta of the particles for photon emission from 24 dipole
*/
mutable vector<Lorentz5Momentum> realEmissionQEDIF24_;
/**
* Properties of the incoming particles
*/
//@{
/**
* Pointers to the BeamParticleData objects
*/
vector<tcBeamPtr> _beams;
/**
* Pointers to the ParticleDataObjects for the partons
*/
vector<tcPDPtr> _partons;
//@}
/**
* Whether the quark is in the + or - z direction
*/
bool _quarkplus;
/**
* QCD emmision type
*/
int QCDRadiationType_;
/**
* Constants for the sampling. The distribution is assumed to have the
* form \f$\frac{c}{{\rm GeV}}\times\left(\frac{{\rm GeV}}{p_T}\right)^n\f$
*/
//@{
/**
* The prefactor, \f$c\f$ for the \f$q\bar{q}\f$ channel for QCD emission
*/
double preqqbarqQCD_;
/**
* The prefactor, \f$c\f$ for the \f$q\bar{q}\f$ channel for QCD emission
*/
double preqqbarqbarQCD_;
/**
* The prefactor, \f$c\f$ for the \f$qg\f$ channel
*/
double preqgQCD_;
/**
* The prefactor, \f$c\f$ for the \f$g\bar{q}\f$ channel
*/
double pregqbarQCD_;
/**
* The prefactor, \f$c\f$ for the \f$q\bar{q}\f$ channel for QED emission
*/
double preqqbarqQED_;
/**
* The prefactor, \f$c\f$ for the \f$q\bar{q}\f$ channel for QED emission
*/
double preqqbarqbarQED_;
/**
* The prefactor, \f$c\f$ for the \f$q\gamma\f$ channel
*/
double preqgQED_;
/**
* The prefactor, \f$c\f$ for the \f$\gamma\bar{q}\f$ channel
*/
double pregqbarQED_;
/**
* The prefactor for final-state QED radiation
*/
double preFFQED_;
/**
* The prefactor for initial- and final-state QED interference
*/
double preIFQED_;
/**
* The prefactors as a vector for easy use
*/
vector<double> prefactorQCD_;
/**
* The prefactors as a vector for easy use
*/
vector<double> prefactorQED_;
//@}
/**
* Minimum transverse momentum of the QCD radiation
*/
Energy minpTQCD_;
/**
* Minimum transverse momentum of the QED radiation (initial-initial)
*/
Energy minpTQEDII_;
/**
* Minimum transverse momentum of the QED radiation (initial-final)
*/
Energy minpTQEDIF_;
/**
* Minimum transverse momentum of the QED radiation (final-final)
*/
Energy minpTQEDFF_;
/**
* Pointer to the object calculating the strong coupling
*/
ShowerAlphaPtr alphaQCD_;
/**
* Pointer to the object calculating the strong coupling
*/
ShowerAlphaPtr alphaQED_;
/**
* Pointers to the intermediate resonances
*/
//@{
/**
* Pointer to the Z ParticleData object
*/
tcPDPtr Z0_;
/**
* Pointer to the photon PartcileData object
*/
tcPDPtr gamma_;
//@}
/**
* Matrix element for spin correlations
*/
ProductionMatrixElement me_;
/**
* Process
*/
int process_;
/**
* Maximum flavour of the incoming quarks
*/
int maxFlavour_;
/**
* Pointers to the vertices for the helicity calculations
*/
//@{
/**
* Pointer to the gluon fermions vertex
*/
AbstractFFVVertexPtr FFGVertex_;
/**
* Pointer to the vertex include one-loop EW corrections
*/
OneLoopFFAWZVertexPtr oneLoopVertex_;
//@}
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of MEqq2gZ2ffPowhegQED. */
template <>
struct BaseClassTrait<Herwig::MEqq2gZ2ffPowhegQED,1> {
/** Typedef of the first base class of MEqq2gZ2ffPowhegQED. */
typedef Herwig::HwMEBase NthBase;
};
/** This template specialization informs ThePEG about the name of
* the MEqq2gZ2ffPowhegQED class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::MEqq2gZ2ffPowhegQED>
: public ClassTraitsBase<Herwig::MEqq2gZ2ffPowhegQED> {
/** Return a platform-independent class name */
static string className() { return "Herwig::MEqq2gZ2ffPowhegQED"; }
/**
* The name of a file containing the dynamic library where the class
* MEqq2gZ2ffPowhegQED is implemented. It may also include several, space-separated,
* libraries if the class MEqq2gZ2ffPowhegQED depends on other classes (base classes
* excepted). In this case the listed libraries will be dynamically
* linked in the order they are specified.
*/
static string library() { return "HwMEHadron.so HwPowhegMEHadron.so"; }
};
/** @endcond */
}
#endif /* HERWIG_MEqq2gZ2ffPowhegQED_H */

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