EvtGenInterface Class Reference

Class to interface EvtGen. More...

#include <EvtGenInterface.h>

Public Member Functions
	EvtGenInterface ()
	Constructor.
	~EvtGenInterface ()
	Destructor.
int	setup (const std::string &decayFileName, const std::string &parentParticle, const std::string &userFileName=std::string(""), bool coherentMixing=true)
	Setup evtgen with the given decay files
int	simulateEvent (MCInitialParticles initial, int inclusiveType, const std::string &inclusiveParticle)
	Generate a single event.
int	simulateDecay (MCParticleGraph &graph, MCParticleGraph::GraphParticle &parent)
	Simulate a particle decay.

Static Public Member Functions
static EvtGen *	createEvtGen (const std::string &decayFileName, bool coherentMixing)
	Create and initialize an EvtGen instance:

Protected Attributes
EvtParticle *	m_parent
	Variable needed for parent particle.
EvtGen *	m_Generator
	Variable needed for EvtGen generator.
EvtId	m_ParentParticle
	Variable needed for parent particle ID.
bool	m_ParentInitialized
	Whether parent particle is initialized.
IOIntercept::OutputToLogMessages	m_logCaptureDebug
	Capture EvtGen log and transform into basf2 logging as B2DEBUG messages.

Static Protected Attributes
static EvtGenFwRandEngine	m_eng
	Variable needed for random generator.

Private Member Functions
int	addParticles2Graph (EvtParticle *particle, MCParticleGraph &graph, ROOT::Math::XYZVector pPrimaryVertex, MCParticleGraph::GraphParticle *parent, double timeOffset=0)
	Convert EvtParticle structure to flat MCParticle list.
void	updateGraphParticle (EvtParticle *eParticle, MCParticleGraph::GraphParticle *gParticle, ROOT::Math::XYZVector pPrimaryVertex, double timeOffset=0)
	Copy parameters from EvtParticle to MCParticle.

Detailed Description

Class to interface EvtGen.

This class is responsible to handle all interaction with evtgen and its classes when generating events. It sets up the models, calls evtgen to generate the events and converts the evtgen particles to a list of MCParticles

Definition at line 36 of file EvtGenInterface.h.

Constructor & Destructor Documentation

EvtGenInterface()

EvtGenInterface ( )

inline

Constructor.

Definition at line 50 of file EvtGenInterface.h.

                     :
      m_parent(0),
      m_Generator(0),
      m_ParentInitialized(false),
      m_logCaptureDebug("EvtGen", LogConfig::c_Debug, LogConfig::c_Warning, 20, 20)
    {}

~EvtGenInterface()

~EvtGenInterface

(

)

Destructor.

Definition at line 36 of file EvtGenInterface.cc.

{
  EvtDecayTable* evtDecayTable = EvtDecayTable::getInstance();
  for (unsigned int i = 0; i < EvtPDL::entries(); ++i) {
    for (int j = 0; j < evtDecayTable->getNMode(i); ++j) {
      delete evtDecayTable->getDecay(i, j);
    }
  }
  if (m_Generator) delete m_Generator;
}

Member Function Documentation

addParticles2Graph()

int addParticles2Graph ( EvtParticle *  particle, MCParticleGraph &  graph, ROOT::Math::XYZVector  pPrimaryVertex, MCParticleGraph::GraphParticle *  parent, double  timeOffset = 0  )

private

Convert EvtParticle structure to flat MCParticle list.

Definition at line 242 of file EvtGenInterface.cc.

{
  //Fill top particle in the tree & starting the queue:
  const int existingParticles = graph.size();
  MCParticleGraph::GraphParticle* p;
  if (parent == NULL)
    p = &graph.addParticle();
  else
    p = parent;
  updateGraphParticle(top, p, pPrimaryVertex);
 
  typedef pair<MCParticleGraph::GraphParticle*, EvtParticle*> halfFamily;
  halfFamily currFamily;
  queue < halfFamily > heritancesQueue;
 
  for (uint idaughter = 0; idaughter < top->getNDaug(); idaughter++) {
    currFamily.first = p;
    currFamily.second = top->getDaug(idaughter);
    heritancesQueue.push(currFamily);
  }
 
  //now we can go through the queue:
  while (!heritancesQueue.empty()) {
    currFamily = heritancesQueue.front(); //get the first entry from the queue
    heritancesQueue.pop(); //remove the entry.
 
    MCParticleGraph::GraphParticle* currMother = currFamily.first;
    EvtParticle* currDaughter = currFamily.second;
 
    //putting the daughter in the graph:
    MCParticleGraph::GraphParticle* graphDaughter = &graph.addParticle();
    updateGraphParticle(currDaughter, graphDaughter, pPrimaryVertex, timeOffset);
 
    //add relation between mother and daughter to graph:
    currMother->decaysInto((*graphDaughter));
 
    int nGrandChildren = currDaughter->getNDaug();
 
    if (nGrandChildren == 0)
      graphDaughter->addStatus(MCParticle::c_StableInGenerator);
    else {
      for (int igrandchild = 0; igrandchild < nGrandChildren; igrandchild++) {
        currFamily.first = graphDaughter;
        currFamily.second = currDaughter->getDaug(igrandchild);
        heritancesQueue.push(currFamily);
      }
    }
  }
 
  return graph.size() - existingParticles;
}

createEvtGen()

EvtGen * createEvtGen ( const std::string &  decayFileName, bool  coherentMixing  )

static

Create and initialize an EvtGen instance:

• Make sure Random engine is setup correctly
• Create evt.pdl on the fly from current contents of particle database
• Add photos/all models
• Use Coherent mixing unless set otherwise

Definition at line 47 of file EvtGenInterface.cc.

{
  // Tauola prints normal things to stderr.. oh well.
  IOIntercept::OutputToLogMessages initLogCapture("EvtGen", LogConfig::c_Info, LogConfig::c_Info);
  initLogCapture.setIndent("  ");
  initLogCapture.start();
  EvtRandom::setRandomEngine(&EvtGenInterface::m_eng);
 
  // Official BelleII models
  std::list<EvtDecayBase*> extraModels = EvtGenModelRegister::getModels();
 
  // Fill model list with pythia, photos etc.
  // The parameter 'false' means that Pythia codes must not be converted,
  // since the conversion is applied to all the decfiles since release-06.
  EvtExternalGenList genList{false};
  EvtAbsRadCorr* radCorrEngine = genList.getPhotosModel();
  list<EvtDecayBase*> modelList = genList.getListOfModels();
  extraModels.insert(extraModels.end(), modelList.begin(), modelList.end());
 
  FileSystem::TemporaryFile tmp;
  EvtGenDatabasePDG::Instance()->WriteEvtGenTable(tmp);
 
  auto mixingMode = EvtCPUtil::Incoherent;
  if (coherentMixing)
    mixingMode =  EvtCPUtil::Coherent;
  else {
    B2WARNING("Evtgen has been set to decay the B mesons incoherently. This is useful as a workaround only to generate Y(5S, 6S) -> BBar for QCD studies.");
    B2WARNING("If you are generating Y(4S) events, you _really_ must use the coherent decay mode.");
  }
 
  EvtGen* evtGen = new EvtGen(DECFileName.c_str(), tmp.getName().c_str(), &EvtGenInterface::m_eng,
                              radCorrEngine, &extraModels,  mixingMode);
 
  initLogCapture.finish();
  return evtGen;
}

setup()

int setup	(	const std::string &	decayFileName,
		const std::string &	parentParticle,
		const std::string &	userFileName = std::string(""),
		bool	coherentMixing = true
	)

Setup evtgen with the given decay files

Definition at line 84 of file EvtGenInterface.cc.

{
  B2DEBUG(20, "Begin initialisation of EvtGen Interface.");
 
  // Tauola prints normal things to stderr.. oh well.
  IOIntercept::OutputToLogMessages initLogCapture("EvtGen", LogConfig::c_Info, LogConfig::c_Info);
  initLogCapture.setIndent("  ");
  initLogCapture.start();
  if (!m_Generator) {
    m_Generator = createEvtGen(DECFileName, coherentMixing);
  }
  if (!userFileName.empty()) {
    m_Generator->readUDecay(userFileName.c_str());
  }
 
  // Setup Parent Particle in rest frame
  if (parentParticle != "") {
    m_ParentInitialized = true;
    m_ParentParticle = EvtPDL::getId(parentParticle);
  }
  initLogCapture.finish();
 
  B2DEBUG(20, "End initialisation of EvtGen Interface.");
 
  return 0;
}

simulateDecay()

int simulateDecay	(	MCParticleGraph &	graph,
		MCParticleGraph::GraphParticle &	parent
	)

Simulate a particle decay.

Definition at line 216 of file EvtGenInterface.cc.

{
  int pdg;
  EvtId id;
  ROOT::Math::PxPyPzEVector momentum = parent.get4Vector();
  ROOT::Math::XYZVector vertex = parent.getVertex();
  EvtVector4R pinit(momentum.E(), momentum.X(), momentum.Y(), momentum.Z());
  m_logCaptureDebug.start();
  // we want to decay the particle so the decay time in the tree needs to be lower
  // than whatever the daughters will get
  parent.setDecayTime(-std::numeric_limits<float>::infinity());
  pdg = parent.getPDG();
  id = EvtPDL::evtIdFromStdHep(pdg);
  m_parent = EvtParticleFactory::particleFactory(id, pinit);
  if (pdg == 10022) // Virtual photon
    m_parent->setVectorSpinDensity();
  else
    m_parent->setDiagonalSpinDensity();
  m_Generator->generateDecay(m_parent);
  m_logCaptureDebug.finish();
  int iPart = addParticles2Graph(m_parent, graph, vertex, &parent, parent.getProductionTime());
  m_parent->deleteTree();
  return iPart;
}

simulateEvent()

int simulateEvent	(	MCInitialParticles	initial,
		int	inclusiveType,
		const std::string &	inclusiveParticle
	)

Generate a single event.

Definition at line 132 of file EvtGenInterface.cc.

{
  EvtId inclusiveParticleID, inclusiveAntiParticleID;
 
  if (!m_ParentInitialized)
    B2FATAL("Parent particle is not initialized.");
  //Init evtgen
 
  ROOT::Math::PxPyPzEVector pParentParticle = initial.getHER() + initial.getLER();
  ROOT::Math::PxPyPzEVector herCMS = initial.getBoostedHER();
  ROOT::Math::XYZVector pPrimaryVertex = initial.getVertex();
 
  EvtVector4R pinit(pParentParticle.E(), pParentParticle.X(), pParentParticle.Y(), pParentParticle.Z());
 
  if (inclusiveType != 0) {
    inclusiveParticleID = EvtPDL::getId(inclusiveParticle);
    if (inclusiveParticleID.getId() < 0)
      B2FATAL("Incorrect inclusive particle " << inclusiveParticle);
    inclusiveAntiParticleID = EvtPDL::chargeConj(inclusiveParticleID);
    if (inclusiveAntiParticleID.getId() < 0) {
      B2FATAL("Cannot find the charge-conjugate particle for "
              << inclusiveParticle);
    }
  }
 
  bool we_got_inclusive_particle = false;
  do {
    m_logCaptureDebug.start();
    m_parent = EvtParticleFactory::particleFactory(m_ParentParticle, pinit);
 
 
    // spin-density matrix for Vector particle produced in e+e-
    EvtSpinDensity rho;
    //Set helicity +1 and -1 to 1.
    rho.setDiag(m_parent->getSpinStates());
    rho.set(1, 1, EvtComplex(0.0, 0.0));
 
    // set spin-density matrix, polarisation axis in CMS defined by alpha,beta Euler angles
    double alpha = herCMS.Phi(), beta = herCMS.Theta(), gamma = 0;
    m_parent->setSpinDensityForwardHelicityBasis(rho, alpha, beta, gamma);
 
 
    m_Generator->generateDecay(m_parent);
    m_logCaptureDebug.finish();
 
    if (inclusiveType != 0) {
      EvtParticle* p = m_parent;
      // following loop will go through generated event and check it for
      // presense of inclusive particle
      do {
        //for (int ii = 0; ii < iPart ; ii++) {
        //std::cout << p->getPDGId() << std::endl;
        if (p->getId() == inclusiveParticleID ||
            (inclusiveType == 2 && p->getId() == inclusiveAntiParticleID)) {
          we_got_inclusive_particle = true;
          break;
        }
        p = p->nextIter(m_parent);
      } while (p != 0);
 
      if (!we_got_inclusive_particle) {
        m_parent->deleteTree();
      }
    } else {
      // we don't do inclusive skimming so any generated event will do
      we_got_inclusive_particle = true;
    }
  } while (!we_got_inclusive_particle);
 
  //  B2INFO("after generate Decay.");
  MCParticleGraph graph;
 
  addInitialParticle(graph, 11, initial.getHER());
  addInitialParticle(graph, -11, initial.getLER());
 
  int iPart = addParticles2Graph(m_parent, graph, pPrimaryVertex, NULL);
  graph.generateList("", MCParticleGraph::c_setDecayInfo | MCParticleGraph::c_checkCyclic);
 
  m_parent->deleteTree();
 
  return iPart; //returns the number of generated particles from evtgen
}

updateGraphParticle()

void updateGraphParticle ( EvtParticle *  eParticle, MCParticleGraph::GraphParticle *  gParticle, ROOT::Math::XYZVector  pPrimaryVertex, double  timeOffset = 0  )

private

Copy parameters from EvtParticle to MCParticle.

Definition at line 296 of file EvtGenInterface.cc.

{
  //updating the GraphParticle information from the EvtParticle information
 
  gParticle->setStatus(MCParticle::c_PrimaryParticle);
  gParticle->setMass(eParticle->mass());
  gParticle->setPDG(EvtPDL::getStdHep(eParticle->getId()));
 
  EvtVector4R EvtP4 = eParticle->getP4Lab();
  ROOT::Math::PxPyPzEVector p4(EvtP4.get(1), EvtP4.get(2), EvtP4.get(3), EvtP4.get(0));
  gParticle->set4Vector(p4);
 
  EvtVector4R Evtpos = eParticle->get4Pos();
 
  ROOT::Math::XYZVector pVertex(Evtpos.get(1)*Unit::mm, Evtpos.get(2)*Unit::mm, Evtpos.get(3)*Unit::mm);
  pVertex = pVertex + pPrimaryVertex;
 
  gParticle->setProductionVertex(pVertex.x(), pVertex.y(), pVertex.z());
  gParticle->setProductionTime((Evtpos.get(0)*Unit::mm / Const::speedOfLight) + timeOffset);
  gParticle->setValidVertex(true);
 
  //add PHOTOS flag
  if (eParticle->getAttribute("FSR")) {
    gParticle->addStatus(MCParticle::c_IsPHOTOSPhoton);
  }
 
}

Member Data Documentation

m_eng

EvtGenFwRandEngine m_eng

staticprotected

Variable needed for random generator.

Definition at line 84 of file EvtGenInterface.h.

m_Generator

EvtGen* m_Generator

protected

Variable needed for EvtGen generator.

Definition at line 85 of file EvtGenInterface.h.

m_logCaptureDebug

IOIntercept::OutputToLogMessages m_logCaptureDebug

protected

Capture EvtGen log and transform into basf2 logging as B2DEBUG messages.

Definition at line 88 of file EvtGenInterface.h.

m_parent

EvtParticle* m_parent

protected

Variable needed for parent particle.

Definition at line 83 of file EvtGenInterface.h.

m_ParentInitialized

bool m_ParentInitialized

protected

Whether parent particle is initialized.

Definition at line 87 of file EvtGenInterface.h.

m_ParentParticle

EvtId m_ParentParticle

protected

Variable needed for parent particle ID.

Definition at line 86 of file EvtGenInterface.h.

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

• generators/evtgen/include/EvtGenInterface.h
• generators/evtgen/src/EvtGenInterface.cc