#include <PythiaDecays.h>

Public Member Functions
const DaughterParticleList &	particleDaughters (ParticlePropagator &particle, CLHEP::HepRandomEngine *)

	PythiaDecays ()

	~PythiaDecays ()

Private Attributes
std::unique_ptr< Pythia8::Pythia >	decayer

std::unique_ptr< gen::P8RndmEngine >	p8RndmEngine

DaughterParticleList	theList

Detailed Description

Definition at line 28 of file PythiaDecays.h.

Constructor & Destructor Documentation

PythiaDecays::PythiaDecays ( )

Definition at line 9 of file PythiaDecays.cc.

References decayer, p8RndmEngine, and sysUtil::pid.

 {
     // inspired by method Pythia8Hadronizer::residualDecay() in GeneratorInterface/Pythia8Interface/src/Py8GunBase.cc
     decayer.reset(new Pythia8::Pythia);
     p8RndmEngine.reset(new gen::P8RndmEngine);
     decayer->setRndmEnginePtr(p8RndmEngine.get());
     decayer->settings.flag("ProcessLevel:all",false);
     decayer->settings.flag("PartonLevel:FSRinResonances",false);
     decayer->settings.flag("ProcessLevel:resonanceDecays",false);
     decayer->init();
 
     // forbid all decays
     // (decays are allowed selectively in the particleDaughters function)
     Pythia8::ParticleData & pdt = decayer->particleData;
     int pid = 1;
     while(pdt.nextId(pid) > pid){
       pid = pdt.nextId(pid);
       pdt.mayDecay(pid,false);
     }
 }

PythiaDecays::~PythiaDecays ( )

Definition at line 31 of file PythiaDecays.cc.

31 {

32 }

Member Function Documentation

const DaughterParticleList & PythiaDecays::particleDaughters	(	ParticlePropagator &	particle,
		CLHEP::HepRandomEngine *	engine
	)

Definition at line 35 of file PythiaDecays.cc.

References decayer, makeParticle(), RawParticle::mass(), RawParticle::momentum(), p8RndmEngine, BaseParticlePropagator::particle(), ParticlePropagator::particleDataTable(), sysUtil::pid, RawParticle::pid(), RawParticle::T(), theList, RawParticle::X(), RawParticle::Y(), and RawParticle::Z().

Referenced by TrajectoryManager::updateWithDaughters().

 {
   edm::RandomEngineSentry<gen::P8RndmEngine> sentry(p8RndmEngine.get(), engine);
 
   theList.clear();
 
   // inspired by method Pythia8Hadronizer::residualDecay() in GeneratorInterface/Pythia8Interface/src/Py8GunBase.cc
   int pid = particle.particle().pid();
   decayer->event.reset();
   Pythia8::Particle py8part( pid , 93, 0, 0, 0, 0, 0, 0,
              particle.particle().momentum().x(), // note: momentum().x() and Px() are the same
              particle.particle().momentum().y(),
              particle.particle().momentum().z(),
              particle.particle().momentum().t(),
              particle.particle().mass() );
   py8part.vProd( particle.particle().X(), particle.particle().Y(), 
          particle.particle().Z(), particle.particle().T() );
   decayer->event.append( py8part );
 
   int nentries_before = decayer->event.size();
   decayer->particleData.mayDecay(pid,true);   // switch on the decay of this and only this particle (avoid double decays)
   decayer->next();                           // do the decay
   decayer->particleData.mayDecay(pid,false);  // switch it off again
   int nentries_after = decayer->event.size();
   if ( nentries_after <= nentries_before ) return theList;
 
   theList.reserve(nentries_after - nentries_before);
 
 
   for ( int ipart=nentries_before; ipart<nentries_after; ipart++ )
     {
       Pythia8::Particle& py8daughter = decayer->event[ipart];
       theList.emplace_back(
                            makeParticle(particle.particleDataTable(),
                                         py8daughter.id(),
                                         XYZTLorentzVector( py8daughter.px(), 
                                                            py8daughter.py(), 
                                                            py8daughter.pz(),
                                                            py8daughter.e() ),
                                         XYZTLorentzVector( py8daughter.xProd(),
                                                            py8daughter.yProd(),
                                                            py8daughter.zProd(),
                                                            py8daughter.tProd() ) ) ).setMass( py8daughter.m() );
     }
 
   return theList;
 }