C++ Interface for the Fortran Bhabha scattering generator BHWide. More...

#include <BHWide.h>

Public Types
enum	Channel { CH_BOTH = 0 , CH_S_ONLY = 1 , CH_T_ONLY = 2 }
	Call needed channels. More...

enum	RandomGenerator { RG_RANMAR = 1 , RG_RANECU = 2 }
	Call random generator. More...

enum	EWCorrectionLib { EC_BABAMC = 1 , EC_ALIBABA = 2 }
	Call electroweak correction. More...

enum	HardBremsModel { HM_HELICITY_AMP = 1 , HM_CALKUL = 2 }
	Call Brem Model. More...

enum	PhotonVacPolarization { PP_OFF = 0 , PP_BHLUMI = 1 , PP_EIDELMAN = 2 , PP_BURKHARDT = 3 }
	Call photon polarization. More...

Public Member Functions
	BHWide ()
	Constructor.

	~BHWide ()
	Destrucotr.

void	setDefaultSettings ()
	Sets the default settings for the BhWide Fortran generator.

void	enableZContribution (bool zContribution=true)
	Enabled the Z contribution.

void	setChannel (Channel channel)
	Set the type of channel which should be used.

void	enableWeights (bool weighted=true)
	Enable the use of weighted events.

void	setRandomGenerator (RandomGenerator randomGenerator)
	Set the type of the randomN nmber generator.

void	enableWeakCorrections (bool weakCorrections=true)
	Enable the use of weak corrections.

void	setElectroWeakCorrectionsLib (EWCorrectionLib ewCorrectionLib)
	Set the type of the electro weak correction library.

void	setHardBremsModel (HardBremsModel hardBremsModel)
	Set the type of the hard bremsstrahlung model.

void	setPhotonVacPolarization (PhotonVacPolarization photonVacPol)
	Set the model for the photon vacuum polarization.

void	setCMSEnergy (double cmsEnergy)
	Sets the CMS energy.

void	setScatAnglePositron (std::pair< double, double > angleRange)
	Sets the theta scattering angle range for the scattered positron.

void	setScatAngleElectron (std::pair< double, double > angleRange)
	Sets the theta scattering angle range for the scattered electron.

void	setMinEnergyFinalStatePos (double minEnergyFinalStatePos)
	Sets the minimal energy for the scattered positron.

void	setMinEnergyFinalStateElc (double minEnergyFinalStateElc)
	Sets the minimal energy for the scattered electron.

void	setMaxAcollinearity (double maxAcollinearity)
	Sets the max acollinearity angle.

void	setInfCutCMSEnergy (double infCutCMSEnergy)
	Sets the CMS energy on which an infrared cut is performed.

void	setMaxRejectionWeight (double maxRejectionWeight)
	Sets the max weight at which events are rejected.

void	setMassZ (double massZ)
	Sets the mass of the Z Boson.

void	setWidthZ (double widthZ)
	Sets the width of the Z Boson.

void	setSinW2 (double sinW2)
	Sets the value for the sinW2.

void	setMassTop (double massTop)
	Sets the mass for the top quark.

void	setMassHiggs (double massHiggs)
	Sets the mass for the Higgs Boson.

void	init ()
	Initializes the generator.

void	generateEvent (MCParticleGraph &mcGraph, ROOT::Math::XYZVector vertex, ROOT::Math::LorentzRotation boost)
	Generates one single event.

void	term ()
	Terminates the generator.

double	getCrossSection ()
	Returns the total cross section of the generated process.

double	getCrossSectionError ()
	Returns the error on the total cross section of the generated process.

Protected Member Functions
void	applySettings ()
	Apply the settings to the internal Fortran generator.

void	storeParticle (MCParticleGraph &mcGraph, const double *mom, int pdg, ROOT::Math::XYZVector vertex, ROOT::Math::LorentzRotation boost, bool isVirtual=false, bool isInitial=false)
	Store a single generated particle into the MonteCarlo graph.

Protected Attributes
bool	m_zContribution
	Z-contribution ON/OFF.

Channel	m_channel
	Channel choice.

bool	m_weighted
	Switch for constant, variable weight.

RandomGenerator	m_randomGenerator
	Type of random number generator.

bool	m_weakCorrections
	Switching ON/OFF weak corrections.

EWCorrectionLib	m_ewCorrectionLib
	Option for ElectroWeak Corrections Library.

HardBremsModel	m_hardBremsModel
	type of MODEL subprogram and QED matrix element for hard bremsstrahlung.

PhotonVacPolarization	m_photonVacPol
	Photon vacuum polarization switch.

double	m_cmsEnergy
	CMS Energy = 2*Ebeam [GeV].

std::pair< double, double >	m_ScatteringAngleRangePositron
	Min and Max value for the scattering angle [deg] of the positron.

std::pair< double, double >	m_ScatteringAngleRangeElectron
	Min and Max value for the scattering angle [deg] of the electron.

double	m_minEnergyFinalStatePos
	Minimum energy [GeV] for final state positron.

double	m_minEnergyFinalStateElc
	Minimum energy [GeV] for final state electron.

double	m_maxAcollinearity
	Maximum acollinearity [deg] of final state e+e-.

double	m_infCutCMSEnergy
	Dimensionless infrared cut on CMS energy of soft photons, ( E_phot > CMSENE*EPSCMS/2 ).

double	m_maxRejectionWeight
	Maximum Weight for rejection (if <= 0, it is reset inside the program).

double	m_massZ
	Z mass [GeV].

double	m_widthZ
	Z width [GeV] (may be recalculated by EW library).

double	m_sinW2
	sin^2(theta_W) (may be recalculated by EW library).

double	m_massTop
	top quark mass [GeV].

double	m_massHiggs
	Higgs mass [GeV].

double	m_crossSection
	The cross section of the generated bhabha scattering events.

double	m_crossSectionError
	The error on the cross section of the generated bhabha scattering events.

Private Attributes
int	m_npar [100]
	Integer parameters for BHWide.

double	m_xpar [100]
	Double parameters for BHWide.

Detailed Description

C++ Interface for the Fortran Bhabha scattering generator BHWide.

IMPOTRANT NOTE: In the case of generating UNWEIGHTED events, the user should check in the OUTPUT if the number of OVERWEIGHTED events and/or the fraction of the corresponding cross section is ACCEPTABLE for his/her desired PRECISION. If not, the value of WTMAX has to be adjusted (increased) accordingly (making a histogram of the weight might be helpful).

Definition at line 32 of file BHWide.h.

Member Enumeration Documentation

◆ Channel

enum Channel

Call needed channels.

Enumerator
CH_BOTH	both s and t-channels + interferences.
CH_S_ONLY	only s-channel (for tests!), with model == HM_CALKUL.
CH_T_ONLY	only t-channel (for tests!), with model == HM_CALKUL.

Definition at line 36 of file BHWide.h.

                 {
      CH_BOTH = 0,    
      CH_S_ONLY = 1,  
      CH_T_ONLY = 2   
    };

◆ EWCorrectionLib

enum EWCorrectionLib

Call electroweak correction.

Enumerator

EC_BABAMC

ElectroWeak Corr.

from BABAMC (obsolete).

EC_ALIBABA

ElectroWeak Corr.

from ALIBABA, RECOMMENDED.

Definition at line 49 of file BHWide.h.

                         {
      EC_BABAMC = 1, 
      EC_ALIBABA = 2 
    };

◆ HardBremsModel

enum HardBremsModel

Call Brem Model.

Enumerator

HM_HELICITY_AMP

obtained by the BHWide authors (helicity amplitudes).

HM_CALKUL

from CALKUL, Nucl.

Phys. B206 (1982) 61.

Definition at line 55 of file BHWide.h.

                        {
      HM_HELICITY_AMP = 1, 
      HM_CALKUL = 2        
    };

◆ PhotonVacPolarization

enum PhotonVacPolarization

Call photon polarization.

Enumerator
PP_OFF	Photon vacuum polarization is off.
PP_BHLUMI	Burkhardt et.al. 1989, as in BHLUMI 2.0x.
PP_EIDELMAN	S. Eidelman, F. Jegerlehner, Z.Phys.C(1995)
PP_BURKHARDT	Burkhardt and Pietrzyk 1995 (Moriond).

Definition at line 61 of file BHWide.h.

                               {
      PP_OFF = 0,       
      PP_BHLUMI = 1,    
      PP_EIDELMAN = 2,  
      PP_BURKHARDT = 3  
    };

◆ RandomGenerator

enum RandomGenerator

Call random generator.

Enumerator
RG_RANMAR	Ranmar generator.
RG_RANECU	Ranecu generator.

Definition at line 43 of file BHWide.h.

                         {
      RG_RANMAR = 1, 
      RG_RANECU = 2  
    };

Constructor & Destructor Documentation

◆ BHWide()

BHWide ( )

Constructor.

Sets the default settings.

Definition at line 60 of file BHWide.cc.

{
  for (int i = 0; i < 100; ++i) {
    m_npar[i] = 0;
    m_xpar[i] = 0.0;
  }
 
  m_crossSection = 0.;
  m_crossSectionError = 0.;
 
  setDefaultSettings();
}

◆ ~BHWide()

~BHWide ( )

Destrucotr.

Definition at line 74 of file BHWide.cc.

{
 
}

Member Function Documentation

◆ applySettings()

void applySettings ( )

protected

Apply the settings to the internal Fortran generator.

Definition at line 152 of file BHWide.cc.

{
  //--------------------
  // Integer parameters
  //--------------------
  int keyZof;
  if (m_zContribution) keyZof = 0;
  else keyZof = 1;
  m_npar[0] = (1000 * keyZof) + (100 * m_channel) + (10 * m_weighted) + m_randomGenerator;
  m_npar[1] = (1000 * m_weakCorrections) + (100 * m_ewCorrectionLib) + (10 * m_hardBremsModel) + m_photonVacPol;
 
  //--------------------
  // Double parameters
  //--------------------
  m_xpar[0]  = m_cmsEnergy;
  m_xpar[1]  = m_ScatteringAngleRangePositron.first;
  m_xpar[2]  = m_ScatteringAngleRangePositron.second;
  m_xpar[3]  = m_ScatteringAngleRangeElectron.first;
  m_xpar[4]  = m_ScatteringAngleRangeElectron.second;
  m_xpar[5]  = m_minEnergyFinalStatePos;
  m_xpar[6]  = m_minEnergyFinalStateElc;
  m_xpar[7]  = m_maxAcollinearity;
  m_xpar[8]  = m_infCutCMSEnergy;
  m_xpar[9]  = m_maxRejectionWeight;
  m_xpar[10] = m_massZ;
  m_xpar[11] = m_widthZ;
  m_xpar[12] = m_sinW2;
  m_xpar[13] = m_massTop;
  m_xpar[14] = m_massHiggs;
 
  int mode = -1;
  bhwide_(&mode, m_xpar, m_npar);
}

◆ enableWeakCorrections()

void enableWeakCorrections ( bool weakCorrections = true )

inline

Enable the use of weak corrections.

Parameters

weakCorrections Set to true to use weak corrections.

Definition at line 102 of file BHWide.h.

102{ m_weakCorrections = weakCorrections; }

◆ enableWeights()

void enableWeights ( bool weighted = true )

inline

Enable the use of weighted events.

Parameters

weighted Set to false to generate events for an unweighted MonteCarlo detector simulation.

Definition at line 92 of file BHWide.h.

92{ m_weighted = weighted; }

◆ enableZContribution()

void enableZContribution ( bool zContribution = true )

inline

Enabled the Z contribution.

Parameters

zContribution Set to true to enabled the Z contribution.

Definition at line 82 of file BHWide.h.

82{ m_zContribution = zContribution; }

◆ generateEvent()

void generateEvent	(	MCParticleGraph &	mcGraph,
		ROOT::Math::XYZVector	vertex,
		ROOT::Math::LorentzRotation	boost
	)

Generates one single event.

Parameters

mcGraph	Reference to the MonteCarlo graph into which the generated particles will be stored.
vertex	generated vertex.
boost	generated boost.

Definition at line 116 of file BHWide.cc.

{
  //Generate event
  int mode = 0;
  bhwide_(&mode, m_xpar, m_npar);
 
  //Store the initial particles as virtual particles into the MCParticleGraph
  storeParticle(mcGraph, momset_.q1, 11, vertex, boost, true);
  storeParticle(mcGraph, momset_.p1, -11, vertex, boost, true);
 
  //Store the final state positron and electron into the MCParticleGraph
  storeParticle(mcGraph, momset_.q2, 11, vertex, boost);
  storeParticle(mcGraph, momset_.p2, -11, vertex, boost);
 
  //Store the real photons into the MCParticleGraph
  for (int iPhot = 0; iPhot <  momset_.nphot; ++iPhot) {
    double photMom[4] = {momset_.phit[0][iPhot], momset_.phit[1][iPhot], momset_.phit[2][iPhot], momset_.phit[3][iPhot]};
    storeParticle(mcGraph, photMom, 22, vertex, boost);
  }
}

◆ getCrossSection()

double getCrossSection ( )

inline

Returns the total cross section of the generated process.

Returns: The total cross section.

Definition at line 205 of file BHWide.h.

205{ return m_crossSection; }

◆ getCrossSectionError()

double getCrossSectionError ( )

inline

Returns the error on the total cross section of the generated process.

Returns: The error on the total cross section.

Definition at line 210 of file BHWide.h.

210{ return m_crossSectionError; }

◆ init()

void init ( )

Initializes the generator.

Sets the default values for the internal Fortran generator.

Definition at line 108 of file BHWide.cc.

{
  int number = 50000;
  glimit_(&number);
  applySettings();
}

◆ setChannel()

void setChannel ( Channel channel )

inline

Set the type of channel which should be used.

Parameters

channel The type of channel: s, t or both.

Definition at line 87 of file BHWide.h.

87{ m_channel = channel; }

◆ setCMSEnergy()

void setCMSEnergy ( double cmsEnergy )

inline

Sets the CMS energy.

Parameters

cmsEnergy The CMS energy in [GeV].

Definition at line 122 of file BHWide.h.

122{ m_cmsEnergy = cmsEnergy; }

◆ setDefaultSettings()

void setDefaultSettings ( )

Sets the default settings for the BhWide Fortran generator.

Definition at line 80 of file BHWide.cc.

{
 
  m_zContribution = true;
  m_channel = CH_BOTH;
  m_weighted = false;
  m_randomGenerator = RG_RANMAR;
  m_weakCorrections = true;
  m_ewCorrectionLib = EC_ALIBABA;
  m_hardBremsModel = HM_CALKUL;
  m_photonVacPol = PP_BURKHARDT;
 
  m_cmsEnergy = 10.58 * Unit::GeV;
  m_ScatteringAngleRangePositron = make_pair(17.0, 150.0); //in [deg]
  m_ScatteringAngleRangeElectron = make_pair(17.0, 150.0); //in [deg]
  m_minEnergyFinalStatePos = 0.2 * Unit::GeV;
  m_minEnergyFinalStateElc = 0.2 * Unit::GeV;
  m_maxAcollinearity = 10.0;
  m_infCutCMSEnergy = 1e-5;
  m_maxRejectionWeight = 3.0;
  m_massZ = 91.1882 * Unit::GeV;
  m_widthZ = 2.4952;
  m_sinW2 = 0.22225;
  m_massTop = 174.3 * Unit::GeV;
  m_massHiggs = 115.0 * Unit::GeV;
}

◆ setElectroWeakCorrectionsLib()

void setElectroWeakCorrectionsLib ( EWCorrectionLib ewCorrectionLib )

inline

Set the type of the electro weak correction library.

Parameters

ewCorrectionLib The electro weak correction library which is used: BABAMC or ALIBABA.

Definition at line 107 of file BHWide.h.

107{ m_ewCorrectionLib = ewCorrectionLib; }

◆ setHardBremsModel()

void setHardBremsModel ( HardBremsModel hardBremsModel )

inline

Set the type of the hard bremsstrahlung model.

Parameters

hardBremsModel The model which is used for the hard bremsstrahlung: helicity amplitudes or CALKUL.

Definition at line 112 of file BHWide.h.

112{ m_hardBremsModel = hardBremsModel; }

◆ setInfCutCMSEnergy()

void setInfCutCMSEnergy ( double infCutCMSEnergy )

inline

Sets the CMS energy on which an infrared cut is performed.

Parameters

infCutCMSEnergy The CMS energy in [Gev] at which an infrared cut is performed.

Definition at line 152 of file BHWide.h.

152{ m_infCutCMSEnergy = infCutCMSEnergy; }

◆ setMassHiggs()

void setMassHiggs ( double massHiggs )

inline

Sets the mass for the Higgs Boson.

Parameters

massHiggs The mass for the Higgs Boson in [GeV].

Definition at line 182 of file BHWide.h.

182{ m_massHiggs = massHiggs; }

◆ setMassTop()

void setMassTop ( double massTop )

inline

Sets the mass for the top quark.

Parameters

massTop The mass for the top quark in [GeV].

Definition at line 177 of file BHWide.h.

177{ m_massTop = massTop; }

◆ setMassZ()

void setMassZ ( double massZ )

inline

Sets the mass of the Z Boson.

Parameters

massZ The mass of the Z Boson in [Gev].

Definition at line 162 of file BHWide.h.

162{ m_massZ = massZ; }

◆ setMaxAcollinearity()

void setMaxAcollinearity ( double maxAcollinearity )

inline

Sets the max acollinearity angle.

Parameters

maxAcollinearity The max acollinearity angle in [deg].

Definition at line 147 of file BHWide.h.

147{ m_maxAcollinearity = maxAcollinearity; }

◆ setMaxRejectionWeight()

void setMaxRejectionWeight ( double maxRejectionWeight )

inline

Sets the max weight at which events are rejected.

Parameters

maxRejectionWeight The weight at which events are rejected.

Definition at line 157 of file BHWide.h.

157{ m_maxRejectionWeight = maxRejectionWeight; }

◆ setMinEnergyFinalStateElc()

void setMinEnergyFinalStateElc ( double minEnergyFinalStateElc )

inline

Sets the minimal energy for the scattered electron.

Parameters

minEnergyFinalStateElc The minimal energy for the scattered electron in [GeV].

Definition at line 142 of file BHWide.h.

142{ m_minEnergyFinalStateElc = minEnergyFinalStateElc; }

◆ setMinEnergyFinalStatePos()

void setMinEnergyFinalStatePos ( double minEnergyFinalStatePos )

inline

Sets the minimal energy for the scattered positron.

Parameters

minEnergyFinalStatePos The minimal energy for the scattered positron in [GeV].

Definition at line 137 of file BHWide.h.

137{ m_minEnergyFinalStatePos = minEnergyFinalStatePos; }

void storeParticle	(	MCParticleGraph &	mcGraph,
		const double *	mom,
		int	pdg,
		ROOT::Math::XYZVector	vertex,
		ROOT::Math::LorentzRotation	boost,
		bool	isVirtual = `false`,
		bool	isInitial = `false`
	)

protected

Store a single generated particle into the MonteCarlo graph.

Parameters

mcGraph	Reference to the MonteCarlo graph into which the particle should be stored.
mom	The 3-momentum of the particle in [GeV].
pdg	The PDG code of the particle.
vertex	Production vertex.
boost	Lorentz boost vector.
isVirtual	If the particle is a virtual particle, such as the incoming particles, set this to true.
isInitial	If the particle is a initial particle for ISR, set this to true.

Definition at line 187 of file BHWide.cc.

{
  //  //Create particle
  //MCParticleGraph::GraphParticle& part = mcGraph.addParticle();
  //if (!isVirtual) {
  //  part.setStatus(MCParticle::c_PrimaryParticle);
  //} else {
  //  part.setStatus(MCParticle::c_IsVirtual);
  //}
  //Create particle
  // RG 6/25/14 Add new flag for ISR "c_Initial"
  MCParticleGraph::GraphParticle& part = mcGraph.addParticle();
  if (isVirtual) {
    part.setStatus(MCParticle::c_IsVirtual);
  } else if (isInitial) {
    part.setStatus(MCParticle::c_Initial);
  }
 
  // every particle from a generator is primary
  part.addStatus(MCParticle::c_PrimaryParticle);
 
  // all particles produced by BHWIDE are stable
  part.addStatus(MCParticle::c_StableInGenerator);
 
  // all photons from BHWIDE are ISR or FSR
  if (pdg == 22 && !isVirtual) {
    part.addStatus(MCParticle::c_IsISRPhoton);
    part.addStatus(MCParticle::c_IsFSRPhoton);
  }
 
  part.setPDG(pdg);
  part.setFirstDaughter(0);
  part.setLastDaughter(0);
  part.setMomentum(ROOT::Math::XYZVector(mom[0], mom[1], mom[2]));
  part.setMass(TDatabasePDG::Instance()->GetParticle(pdg)->Mass());
  part.setEnergy(mom[3]);
 
  //boost
  ROOT::Math::PxPyPzEVector p4 = part.get4Vector();
  p4.SetPz(-1.0 * p4.Pz()); //BHWIDE uses other direction convention
  p4 = boost * p4;
  part.set4Vector(p4);
 
  //set vertex
  if (!isInitial) {
    ROOT::Math::XYZVector v3 = part.getProductionVertex();
    v3 = v3 + vertex;
    part.setProductionVertex(v3);
    part.setValidVertex(true);
  }
}

◆ term()

void term ( )

Terminates the generator.

Closes the internal Fortran generator and retrieves the total cross section.

Definition at line 138 of file BHWide.cc.

{
  int mode = 2;
  bhwide_(&mode, m_xpar, m_npar);
 
  //Get the cross section
  m_crossSection      = m_xpar[9];
  m_crossSectionError = m_xpar[10];
}

double m_widthZ

protected

Z width [GeV] (may be recalculated by EW library).

Definition at line 235 of file BHWide.h.

◆ m_xpar

double m_xpar[100]

private

Double parameters for BHWide.

Definition at line 262 of file BHWide.h.

◆ m_zContribution

bool m_zContribution

protected

Z-contribution ON/OFF.

Definition at line 215 of file BHWide.h.

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

generators/bhwide/include/BHWide.h
generators/bhwide/src/BHWide.cc

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Detailed Description

Member Enumeration Documentation

◆ Channel

◆ EWCorrectionLib

◆ HardBremsModel

◆ PhotonVacPolarization

◆ RandomGenerator

Constructor & Destructor Documentation

◆ BHWide()

◆ ~BHWide()

Member Function Documentation

◆ applySettings()

◆ enableWeakCorrections()

◆ enableWeights()

◆ enableZContribution()

◆ generateEvent()

◆ getCrossSection()

◆ getCrossSectionError()

◆ init()

◆ setChannel()

◆ setCMSEnergy()

◆ setDefaultSettings()

◆ setElectroWeakCorrectionsLib()

◆ setHardBremsModel()

◆ setInfCutCMSEnergy()

◆ setMassHiggs()

◆ setMassTop()

◆ setMassZ()

◆ setMaxAcollinearity()

◆ setMaxRejectionWeight()

◆ setMinEnergyFinalStateElc()

◆ setMinEnergyFinalStatePos()

◆ setPhotonVacPolarization()

◆ setRandomGenerator()

◆ setScatAngleElectron()

◆ setScatAnglePositron()

◆ setSinW2()

◆ setWidthZ()

◆ storeParticle()

◆ term()

Member Data Documentation

◆ m_channel

◆ m_cmsEnergy

◆ m_crossSection

◆ m_crossSectionError

◆ m_ewCorrectionLib

◆ m_hardBremsModel

◆ m_infCutCMSEnergy

◆ m_massHiggs

◆ m_massTop

◆ m_massZ

◆ m_maxAcollinearity

◆ m_maxRejectionWeight

◆ m_minEnergyFinalStateElc

◆ m_minEnergyFinalStatePos

◆ m_npar

◆ m_photonVacPol

◆ m_randomGenerator

◆ m_ScatteringAngleRangeElectron

◆ m_ScatteringAngleRangePositron

◆ m_sinW2

◆ m_weakCorrections

◆ m_weighted

◆ m_widthZ

◆ m_xpar

◆ m_zContribution