Pythia8::WZVetoedShower Class Reference

This UserHook should be used when showering W, Z or other colourless resonances generated with PoWHEG. More...

Inheritance diagram for Pythia8::WZVetoedShower:

Collaboration diagram for Pythia8::WZVetoedShower:

Public Member Functions
	WZVetoedShower ()
	~WZVetoedShower ()
bool	doVetoMPIStep (int nMPI, const Event &)
	doVetoMPIStep is called immediately after the MPI generation In this case it never actually vetoes the MPI, but since it is called before the ISR veto check this is a convenient place to find the PoWHEG scale from the LHEF event More...
bool	doVetoISREmission (int, const Event &evt, int iSys)
	This is called after the generation of each new ISR emission Can use it to test if the last generated emission is above the veto scale. More...
bool	doVetoFSREmission (int, const Event &evt, int iSys, bool)
	This is similar to the ISR veto. More...
bool	canVetoMPIStep ()
	Switch on calling of doVetoMPIStep. More...
int	numberVetoMPIStep ()
	Call doVetoMIStep once. More...
bool	canVetoISREmission ()
	Switch on veto of ISR. More...
bool	canVetoFSREmission ()
	Switch off veto of FSR. More...

Private Attributes
double	m_powhegScale

Detailed Description

This UserHook should be used when showering W, Z or other colourless resonances generated with PoWHEG.

The following setting must be activated in Pythia:

SpaceShower:pTMaxMatch = 2 TimeShower:pTMaxMatch = 2

These set the limit for emission from both initial and final state radiation to the kinematic (beam) energy. The veto hook then vetos any emission that would be above the appropriate scale.

In the cases of colourless resonance production there should be no FSR emission from PoWHEG, therefore the veto determines the pT of every Pythia emission relative to the beam, and vetos if it is above the PoWHEG scale.

This is ok because

1) Although you might think the pT should also be determined relative to any PoWHEG ISR emission, there is no way PoWHEG could have generated an emission off its own ISR. 2) There can be FSR off what was a PoWHEG ISR leg, but again, PoWHEG could never have generated that emission, so you only need to compare to the incoming (beam) legs.

This is in contrast to QCD production, which requires a different veto scheme. As such, this hook...

         ...SHOULD NOT BE USED FOR QCD JET PRODUCTION!!

Definition at line 44 of file WZVetoedShower.cxx.

Constructor & Destructor Documentation

WZVetoedShower()

Pythia8::WZVetoedShower::WZVetoedShower ( )

inline

Definition at line 48 of file WZVetoedShower.cxx.

                    : m_powhegScale(0.){
 
      std::cout<<"*******************************************************************"<<std::endl;
      std::cout<<"*                                                                 *"<<std::endl;
      std::cout<<"* Using vetoed shower for PoWHEG colourless resonance production! *"<<std::endl;
      std::cout<<"*                                                                 *"<<std::endl;
      std::cout<<"*******************************************************************"<<std::endl;
      
    }

~WZVetoedShower()

Pythia8::WZVetoedShower::~WZVetoedShower ( )

inline

Definition at line 58 of file WZVetoedShower.cxx.

{}

Member Function Documentation

canVetoFSREmission()

bool Pythia8::WZVetoedShower::canVetoFSREmission ( )

inline

Switch off veto of FSR.

Definition at line 121 of file WZVetoedShower.cxx.

{return true;}

canVetoISREmission()

bool Pythia8::WZVetoedShower::canVetoISREmission ( )

inline

Switch on veto of ISR.

Definition at line 119 of file WZVetoedShower.cxx.

{return true;}

canVetoMPIStep()

bool Pythia8::WZVetoedShower::canVetoMPIStep ( )

inline

Switch on calling of doVetoMPIStep.

Definition at line 115 of file WZVetoedShower.cxx.

{return true;}

doVetoFSREmission()

bool Pythia8::WZVetoedShower::doVetoFSREmission ( int  , const Event &  evt, int  iSys, bool    )

inline

This is similar to the ISR veto.

Definition at line 101 of file WZVetoedShower.cxx.

                                                                 {
 
      // only veto emissions from the hard system
      if(iSys != 0) return false;
      
      size_t emission = Pythia8_UserHooks::findLastFSREmission(evt);
 
      // Veto if above the POWHEG scale
      if (evt[emission].pT() > m_powhegScale) return true;
 
      return false;
    }

doVetoISREmission()

bool Pythia8::WZVetoedShower::doVetoISREmission ( int  , const Event &  evt, int  iSys  )

inline

This is called after the generation of each new ISR emission Can use it to test if the last generated emission is above the veto scale.

Definition at line 85 of file WZVetoedShower.cxx.

                                                           {
 
      // only veto emissions from the hard system
      if(iSys != 0) return false;
      
      size_t emission = Pythia8_UserHooks::findLastISREmission(evt);
 
      // Veto emission above the veto scale
      if(evt[emission].pT() > m_powhegScale) return true;
 
      return false;
    }

doVetoMPIStep()

bool Pythia8::WZVetoedShower::doVetoMPIStep ( int  nMPI, const Event &    )

inline

doVetoMPIStep is called immediately after the MPI generation In this case it never actually vetoes the MPI, but since it is called before the ISR veto check this is a convenient place to find the PoWHEG scale from the LHEF event

Definition at line 66 of file WZVetoedShower.cxx.

                                               {
 
      // Only do anything on the first call.
      if(nMPI > 1) return false;
      
      m_powhegScale = infoPtr->QRen();
//      m_powhegScale = infoPtr->QFac();
 
//      std::cout<<" ******** veto scale = "<<m_powhegScale<<", "<<infoPtr->QRen() <<" *********"<<std::endl;  
      
      return false;
    }

numberVetoMPIStep()

int Pythia8::WZVetoedShower::numberVetoMPIStep ( )

inline

Call doVetoMIStep once.

Definition at line 117 of file WZVetoedShower.cxx.

{return 1;}

Member Data Documentation

m_powhegScale

double Pythia8::WZVetoedShower::m_powhegScale

private

Definition at line 125 of file WZVetoedShower.cxx.

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

• WZVetoedShower.cxx