TagVertexModule.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#include <analysis/modules/TagVertex/TagVertexModule.h>
 
//to help printing out stuff
#include<sstream>
 
// framework aux
#include <framework/gearbox/Unit.h>
#include <framework/gearbox/Const.h>
#include <framework/logging/Logger.h>
 
// dataobjects
#include <analysis/dataobjects/RestOfEvent.h>
#include <analysis/dataobjects/FlavorTaggerInfo.h>
 
// utilities
#include <analysis/utility/PCmsLabTransform.h>
#include <analysis/variables/TrackVariables.h>
#include <analysis/utility/ParticleCopy.h>
#include <analysis/utility/CLHEPToROOT.h>
#include <analysis/utility/ROOTToCLHEP.h>
#include <analysis/utility/DistanceTools.h>
#include <analysis/utility/RotationTools.h>
 
// rave
#include <analysis/VertexFitting/RaveInterface/RaveSetup.h>
#include <analysis/VertexFitting/RaveInterface/RaveVertexFitter.h>
 
#include <CLHEP/Geometry/Point3D.h>
#include <CLHEP/Matrix/SymMatrix.h>
#include <CLHEP/Vector/LorentzVector.h>
 
// mdst dataobject
#include <mdst/dataobjects/HitPatternVXD.h>
 
// Magnetic field
#include <framework/geometry/BFieldManager.h>
 
#include <TVector.h>
#include <TRotation.h>
#include <Math/Vector4D.h>
 
using namespace std;
using namespace Belle2;

static const double realNaN = std::numeric_limits<double>::quiet_NaN();

static const ROOT::Math::XYZVector vecNaN(realNaN, realNaN, realNaN);

static const double arrayNaN[] = {
  realNaN, realNaN, realNaN,
  realNaN, realNaN, realNaN,
  realNaN, realNaN, realNaN,
};

static const TMatrixDSym matNaN(3, arrayNaN);
 
// import tools from RotationTools.h
using RotationTools::rotateTensor;
using RotationTools::rotateTensorInv;
using RotationTools::toSymMatrix;
using RotationTools::toVec;
using RotationTools::getUnitOrthogonal;
 
//-----------------------------------------------------------------
//                 Register the Module
//-----------------------------------------------------------------
REG_MODULE(TagVertex);
 
//-----------------------------------------------------------------
//                 Implementation
//-----------------------------------------------------------------
 
TagVertexModule::TagVertexModule() : Module(),
  m_Bfield(0), m_fitTruthStatus(0), m_rollbackStatus(0), m_fitPval(0), m_mcTagLifeTime(-1), m_mcPDG(0), m_mcLifeTimeReco(-1),
  m_deltaT(0), m_deltaTErr(0), m_mcDeltaTau(0), m_mcDeltaT(0),
  m_FitType(0), m_tagVl(0),
  m_truthTagVl(0), m_tagVlErr(0), m_tagVol(0), m_truthTagVol(0), m_tagVolErr(0), m_tagVNDF(0), m_tagVChi2(0), m_tagVChi2IP(0),
  m_kFitReqReducedChi2(5),
  m_verbose(true)
{
  // Set module properties
  setDescription("Tag side Vertex Fitter for modular analysis");
  setPropertyFlags(c_ParallelProcessingCertified);
 
  // Parameter definitions
  addParam("listName", m_listName, "name of particle list", string(""));
  addParam("confidenceLevel", m_confidenceLevel,
           "required confidence level of fit to keep particles in the list. Note that even with confidenceLevel == 0.0, errors during the fit might discard Particles in the list. confidenceLevel = -1 if an error occurs during the fit",
           0.001);
  addParam("MCAssociation", m_useMCassociation,
           "'': no MC association. breco: use standard Breco MC association. internal: use internal MC association", string("breco"));
  addParam("constraintType", m_constraintType,
           "Choose the type of the constraint: noConstraint, IP (tag tracks constrained to be within the beam spot), tube (long tube along the BTag line of flight, only for fully reconstruced B rec), boost (long tube along the Upsilon(4S) boost direction), (breco)",
           string("tube"));
  addParam("trackFindingType", m_trackFindingType,
           "Choose how to reconstruct the tracks on the tag side: standard, standard_PXD",
           string("standard_PXD"));
  addParam("maskName", m_roeMaskName,
           "Choose ROE mask to get particles from ", string(RestOfEvent::c_defaultMaskName));
  addParam("askMCInformation", m_mcInfo,
           "TRUE when requesting MC Information from the tracks performing the vertex fit", false);
  addParam("reqPXDHits", m_reqPXDHits,
           "Minimum number of PXD hits for a track to be used in the vertex fit", 0);
  addParam("fitAlgorithm", m_fitAlgo,
           "Fitter used for the tag vertex fit: Rave or KFit", string("KFit"));
  addParam("kFitReqReducedChi2", m_kFitReqReducedChi2,
           "The required chi2/ndf to accept the kFit result, if it is higher, iteration procedure is applied", 5.0);
  addParam("useTruthInFit", m_useTruthInFit,
           "Use the true track parameters in the vertex fit", false);
  addParam("useRollBack", m_useRollBack,
           "Use rolled back non-primary tracks", false);
}
 
void TagVertexModule::initialize()
{
  // magnetic field
  m_Bfield = BFieldManager::getFieldInTesla(m_BeamSpotCenter).Z();
  // RAVE setup
  analysis::RaveSetup::initialize(1, m_Bfield);
  B2INFO("TagVertexModule : magnetic field = " << m_Bfield);
  // truth fit status will be set to 2 only if the MC info cannot be recovered
  if (m_useTruthInFit) m_fitTruthStatus = 1;
  // roll back status will be set to 2 only if the MC info cannot be recovered
  if (m_useRollBack) m_rollbackStatus = 1;
 
  //input
  StoreArray<Particle>().isRequired();
  m_plist.isRequired(m_listName);
  // output
  m_verArray.registerInDataStore();
  StoreArray<Particle>().registerRelationTo(m_verArray);
  //check if the fitting algorithm name is set correctly
  if (m_fitAlgo != "Rave" && m_fitAlgo != "KFit")
    B2FATAL("TagVertexModule: invalid fitting algorithm (must be set to either Rave or KFit).");
  if (m_useRollBack && m_useTruthInFit)
    B2FATAL("TagVertexModule: invalid fitting option (useRollBack and useTruthInFit cannot be simultaneously set to true).");
  //temporary while the one track fit is broken
  if (m_trackFindingType == "singleTrack" || m_trackFindingType == "singleTrack_PXD")
    B2FATAL("TagVertexModule : the singleTrack option is temporarily broken.");
}
 
// cppcheck-suppress uselessOverride
void TagVertexModule::beginRun()
{
  //TODO: set magnetic field for each run
  //m_Bfield = BFieldMap::Instance().getBField(m_BeamSpotCenter).Z();
}
 
void TagVertexModule::event()
{
  if (!m_plist) {
    B2ERROR("TagVertexModule: ParticleList " << m_listName << " not found");
    return;
  }
 
  // output
  analysis::RaveSetup::initialize(1, m_Bfield);
 
  std::vector<unsigned int> toRemove;
 
  for (unsigned i = 0; i < m_plist->getListSize(); ++i) {
    resetReturnParams();
 
    const Particle* particle =  m_plist->getParticle(i);
    if (m_useMCassociation == "breco" || m_useMCassociation == "internal") BtagMCVertex(particle);
    bool ok = doVertexFit(particle);
    if (ok) deltaT(particle);
 
    if ((m_fitPval < m_confidenceLevel && m_confidenceLevel != 0)
        || (m_fitPval <= m_confidenceLevel && m_confidenceLevel == 0)) {
      toRemove.push_back(particle->getArrayIndex());
    } else {
      // save information in the Vertex StoreArray
      TagVertex* ver = m_verArray.appendNew();
      // create relation: Particle <-> Vertex
      particle->addRelationTo(ver);
      // fill Vertex with content
      if (ok) {
        ver->setTagVertex(m_tagV);
        ver->setTagVertexErrMatrix(m_tagVErrMatrix);
        ver->setTagVertexPval(m_fitPval);
        ver->setDeltaT(m_deltaT);
        ver->setDeltaTErr(m_deltaTErr);
        ver->setMCTagVertex(m_mcTagV);
        ver->setMCTagBFlavor(m_mcPDG);
        ver->setMCDeltaTau(m_mcDeltaTau);
        ver->setMCDeltaT(m_mcDeltaT);
        ver->setFitType(m_FitType);
        ver->setNTracks(m_tagParticles.size());
        ver->setTagVl(m_tagVl);
        ver->setTruthTagVl(m_truthTagVl);
        ver->setTagVlErr(m_tagVlErr);
        ver->setTagVol(m_tagVol);
        ver->setTruthTagVol(m_truthTagVol);
        ver->setTagVolErr(m_tagVolErr);
        ver->setTagVNDF(m_tagVNDF);
        ver->setTagVChi2(m_tagVChi2);
        ver->setTagVChi2IP(m_tagVChi2IP);
        ver->setVertexFitParticles(m_raveParticles);
        ver->setVertexFitMCParticles(m_raveMCParticles);
        ver->setRaveWeights(m_raveWeights);
        ver->setConstraintType(m_constraintType);
        ver->setConstraintCenter(m_constraintCenter);
        ver->setConstraintCov(m_constraintCov);
        ver->setFitTruthStatus(m_fitTruthStatus);
        ver->setRollBackStatus(m_rollbackStatus);
      } else {
        ver->setTagVertex(m_tagV);
        ver->setTagVertexPval(-1.);
        ver->setDeltaT(m_deltaT);
        ver->setDeltaTErr(m_deltaTErr);
        ver->setMCTagVertex(m_mcTagV);
        ver->setMCTagBFlavor(0.);
        ver->setMCDeltaTau(m_mcDeltaTau);
        ver->setMCDeltaT(m_mcDeltaT);
        ver->setFitType(m_FitType);
        ver->setNTracks(m_tagParticles.size());
        ver->setTagVl(m_tagVl);
        ver->setTruthTagVl(m_truthTagVl);
        ver->setTagVlErr(m_tagVlErr);
        ver->setTagVol(m_tagVol);
        ver->setTruthTagVol(m_truthTagVol);
        ver->setTagVolErr(m_tagVolErr);
        ver->setTagVNDF(-1111.);
        ver->setTagVChi2(-1111.);
        ver->setTagVChi2IP(-1111.);
        ver->setVertexFitParticles(m_raveParticles);
        ver->setVertexFitMCParticles(m_raveMCParticles);
        ver->setRaveWeights(m_raveWeights);
        ver->setConstraintType(m_constraintType);
        ver->setConstraintCenter(m_constraintCenter);
        ver->setConstraintCov(m_constraintCov);
        ver->setFitTruthStatus(m_fitTruthStatus);
        ver->setRollBackStatus(m_rollbackStatus);
      }
    }
  }
  m_plist->removeParticles(toRemove);
 
  //free memory allocated by rave. initialize() would be enough, except that we must clean things up before program end...
  //
  analysis::RaveSetup::getInstance()->reset();
}
 
bool TagVertexModule::doVertexFit(const Particle* Breco)
{
  //reset the fit truth status in case it was set to 2 in a previous fit
 
  if (m_useTruthInFit) m_fitTruthStatus = 1;
 
  //reset the roll back status in case it was set to 2 in a previous fit
 
  if (m_useRollBack) m_rollbackStatus = 1;
 
  //set constraint type, reset pVal and B field
 
  m_fitPval = 1;
 
  if (!(Breco->getRelatedTo<RestOfEvent>())) {
    m_FitType = -1;
    return false;
  }
 
  if (m_Bfield == 0) {
    B2ERROR("TagVertex: No magnetic field");
    return false;
  }
 
  // recover beam spot info
 
  m_BeamSpotCenter = m_beamSpotDB->getIPPosition();
  m_BeamSpotCov.ResizeTo(3, 3);
  m_BeamSpotCov = m_beamSpotDB->getCovVertex();
 
  //make the beam spot bigger for the standard constraint
 
  double beta = PCmsLabTransform().getBoostVector().R();
  double bg = beta / sqrt(1 - beta * beta);
 
  //TODO: What's the origin of these numbers?
  double tauB = 1.519; //B0 lifetime in ps
  double c = Const::speedOfLight / 1000.; // cm ps-1
  double lB0  = tauB * bg * c;
 
  //tube length here set to 20 * 2 * c tau beta gamma ~= 0.5 cm, should be enough to not bias the decay
  //time but should still help getting rid of some pions from kshorts
  m_constraintCov.ResizeTo(3, 3);
  if (m_constraintType == "IP")         tie(m_constraintCenter, m_constraintCov) = findConstraintBoost(2 * lB0);
  else if (m_constraintType == "tube")  tie(m_constraintCenter, m_constraintCov) = findConstraintBTube(Breco, 200 * lB0);
  else if (m_constraintType == "boost") tie(m_constraintCenter, m_constraintCov) = findConstraintBoost(200 * lB0);
  else if (m_constraintType == "breco") tie(m_constraintCenter, m_constraintCov) = findConstraint(Breco, 200 * lB0);
  else if (m_constraintType == "noConstraint") m_constraintCenter = ROOT::Math::XYZVector(); //zero vector
  else  {
    B2ERROR("TagVertex: Invalid constraintType selected");
    return false;
  }
 
  if (m_constraintCenter == vecNaN) {
    B2ERROR("TagVertex: No correct fit constraint");
    return false;
  }
 
  /* Depending on the user's choice, one of the possible algorithms is chosen for the fit. In case the algorithm does not converge, in order to assure
     high efficiency, the next algorithm less restrictive is used. I.e, if standard_PXD does not work, the program tries with standard.
  */
 
  m_FitType = 0;
  double minPVal = (m_fitAlgo != "KFit") ? 0.001 : 0.;
  bool ok = false;
 
  if (m_trackFindingType == "standard_PXD") {
    m_tagParticles = getTagTracks_standardAlgorithm(Breco, 1);
    if (m_tagParticles.size() > 0) {
      ok = makeGeneralFit();
      m_FitType = 3;
    }
  }
 
  if (ok == false || m_fitPval < minPVal || m_trackFindingType == "standard") {
    m_tagParticles = getTagTracks_standardAlgorithm(Breco, m_reqPXDHits);
    ok = m_tagParticles.size() > 0;
    if (ok) {
      ok = makeGeneralFit();
      m_FitType = 4;
    }
  }
 
  if ((ok == false || (m_fitPval <= 0. && m_fitAlgo == "Rave")) && m_constraintType != "noConstraint") {
    tie(m_constraintCenter, m_constraintCov) = findConstraintBoost(200 * lB0);
    ok = (m_constraintCenter != vecNaN);
    if (ok) {
      m_tagParticles = getTagTracks_standardAlgorithm(Breco, m_reqPXDHits);
      ok = (m_tagParticles.size() > 0);
    }
    if (ok) {
      ok = makeGeneralFit();
      m_FitType = 5;
    }
  }
 
  return ok;
}
 
pair<ROOT::Math::XYZVector, TMatrixDSym> TagVertexModule::findConstraint(const Particle* Breco, double cut) const
{
  if (Breco->getPValue() < 0.) return make_pair(vecNaN, matNaN);
 
  TMatrixDSym beamSpotCov(3);
  beamSpotCov = m_beamSpotDB->getCovVertex();
 
  analysis::RaveSetup::getInstance()->setBeamSpot(m_BeamSpotCenter, beamSpotCov);
 
  double pmag = Breco->getMomentumMagnitude();
  double xmag = (Breco->getVertex() - m_BeamSpotCenter).R();
 
 
  TMatrixDSym TerrMatrix = Breco->getMomentumVertexErrorMatrix();
  TMatrixDSym PerrMatrix(7);
 
  for (int i = 0; i < 3; ++i) {
    for (int j = 0; j < 3; ++j) {
      if (i == j) {
        PerrMatrix(i, j) = (beamSpotCov(i, j) + TerrMatrix(i, j)) * pmag / xmag;
      } else {
        PerrMatrix(i, j) = TerrMatrix(i, j);
      }
      PerrMatrix(i + 4, j + 4) = TerrMatrix(i + 4, j + 4);
    }
  }
 
  PerrMatrix(3, 3) = 0.;
 
  //Copy Breco, but use errors as are in PerrMatrix
  Particle* Breco2 = ParticleCopy::copyParticle(Breco);
  Breco2->setMomentumVertexErrorMatrix(PerrMatrix);
 
 
  const Particle* BRecoRes = doVertexFitForBTube(Breco2, "kalman");
  if (BRecoRes->getPValue() < 0) return make_pair(vecNaN, matNaN); //problems
 
  // Overall error matrix
  TMatrixDSym errFinal = TMatrixDSym(Breco->getVertexErrorMatrix() + BRecoRes->getVertexErrorMatrix());
 
  // TODO : to be developed the extraction of the momentum from the rave fitted track
 
  // Get expected pBtag 4-momentum using transverse-momentum conservation
  ROOT::Math::XYZVector BvertDiff = pmag * (Breco->getVertex() - BRecoRes->getVertex()).Unit();
  ROOT::Math::PxPyPzMVector pBrecEstimate(BvertDiff.X(), BvertDiff.Y(), BvertDiff.Z(), Breco->getPDGMass());
  ROOT::Math::PxPyPzMVector pBtagEstimate = PCmsLabTransform::labToCms(pBrecEstimate);
  pBtagEstimate.SetPxPyPzE(-pBtagEstimate.px(), -pBtagEstimate.py(), -pBtagEstimate.pz(), pBtagEstimate.E());
  pBtagEstimate = PCmsLabTransform::cmsToLab(pBtagEstimate);
 
  // rotate err-matrix such that pBrecEstimate goes to eZ
  TMatrixD TubeZ = rotateTensorInv(pBrecEstimate.Vect(), errFinal);
 
  TubeZ(2, 2) = cut * cut;
  TubeZ(2, 0) = 0; TubeZ(0, 2) = 0;
  TubeZ(2, 1) = 0; TubeZ(1, 2) = 0;
 
 
  // rotate err-matrix such that eZ goes to pBtagEstimate
  TMatrixD Tube = rotateTensor(pBtagEstimate.Vect(), TubeZ);
 
  // Standard algorithm needs no shift
  return make_pair(m_BeamSpotCenter, toSymMatrix(Tube));
}
 
pair<ROOT::Math::XYZVector, TMatrixDSym> TagVertexModule::findConstraintBTube(const Particle* Breco, double cut)
{
  //Use Breco as the creator of the B tube.
  if ((Breco->getVertexErrorMatrix()(2, 2)) == 0.0) {
    B2WARNING("In TagVertexModule::findConstraintBTube: cannot get a proper vertex for BReco. BTube constraint replaced by Boost.");
    return findConstraintBoost(cut);
  }
 
 
  //vertex fit will give the intersection between the beam spot and the trajectory of the B
  //(base of the BTube, or primary vtx cov matrix)
  const Particle* tubecreatorBCopy = doVertexFitForBTube(Breco, "avf");
  if (tubecreatorBCopy->getPValue() < 0) return make_pair(vecNaN, matNaN); //if problems
 
 
  //get direction of B tag = opposite direction of B rec in CMF
  ROOT::Math::PxPyPzEVector pBrec = tubecreatorBCopy->get4Vector();
 
  //if we want the true info, replace the 4vector by the true one
  if (m_useTruthInFit) {
    const MCParticle* mcBr = Breco->getRelated<MCParticle>();
    if (mcBr)
      pBrec = mcBr->get4Vector();
    else
      m_fitTruthStatus = 2;
  }
  ROOT::Math::PxPyPzEVector pBtag = PCmsLabTransform::labToCms(pBrec);
  pBtag.SetPxPyPzE(-pBtag.px(), -pBtag.py(), -pBtag.pz(), pBtag.E());
  pBtag = PCmsLabTransform::cmsToLab(pBtag);
 
  //To create the B tube, strategy is: take the primary vtx cov matrix, and add to it a cov
  //matrix corresponding to an very big error in the direction of the B tag
  TMatrixDSym pv = tubecreatorBCopy->getVertexErrorMatrix();
 
  //print some stuff if wanted
  if (m_verbose) {
    B2DEBUG(10, "Brec decay vertex before fit: " << printVector(Breco->getVertex()));
    B2DEBUG(10, "Brec decay vertex after fit: " << printVector(tubecreatorBCopy->getVertex()));
    B2DEBUG(10, "Brec direction before fit: " << printVector(float(1. / Breco->getP()) * Breco->getMomentum()));
    B2DEBUG(10, "Brec direction after fit: " << printVector(float(1. / tubecreatorBCopy->getP()) * tubecreatorBCopy->getMomentum()));
    B2DEBUG(10, "IP position: " << printVector(m_BeamSpotCenter));
    B2DEBUG(10, "IP covariance: " << printMatrix(m_BeamSpotCov));
    B2DEBUG(10, "Brec primary vertex: " << printVector(tubecreatorBCopy->getVertex()));
    B2DEBUG(10, "Brec PV covariance: " << printMatrix(pv));
    B2DEBUG(10, "BTag direction: " << printVector((1. / pBtag.P())*pBtag.Vect()));
  }
 
  //make a long error matrix along BTag direction
  TMatrixD longerror(3, 3); longerror(2, 2) = cut * cut;
 
 
  // make rotation matrix from z axis to BTag line of flight
  TMatrixD longerrorRotated = rotateTensor(pBtag.Vect(), longerror);
 
  //pvNew will correspond to the covariance matrix of the B tube
  TMatrixD pvNew = TMatrixD(pv) + longerrorRotated;
 
  //set the constraint
  ROOT::Math::XYZVector constraintCenter = tubecreatorBCopy->getVertex();
 
  //if we want the true info, set the centre of the constraint to the primary vertex
  if (m_useTruthInFit) {
    const MCParticle* mcBr = Breco->getRelated<MCParticle>();
    if (mcBr) {
      constraintCenter = mcBr->getProductionVertex();
    }
  }
 
  if (m_verbose) {
    B2DEBUG(10, "IPTube covariance: " << printMatrix(pvNew));
  }
 
  //The following is done to do the BTube constraint with a virtual track
  //(ie KFit way)
 
  m_tagMomentum = pBtag;
 
  m_pvCov.ResizeTo(pv);
  m_pvCov = pv;
 
  return make_pair(constraintCenter, toSymMatrix(pvNew));
}
 
pair<ROOT::Math::XYZVector, TMatrixDSym> TagVertexModule::findConstraintBoost(double cut) const
{
  double d = 20e-4; //average transverse distance flown by B0
 
  //make a long error matrix along boost direction
  TMatrixD longerror(3, 3); longerror(2, 2) = cut * cut;
  longerror(0, 0) = longerror(1, 1) = d * d;
 
  ROOT::Math::XYZVector boostDir = PCmsLabTransform().getBoostVector().Unit();
 
  TMatrixD longerrorRotated = rotateTensor(boostDir, longerror);
 
  //Extend error of BeamSpotCov matrix in the boost direction
  TMatrixDSym beamSpotCov = m_beamSpotDB->getCovVertex();
  TMatrixD Tube = TMatrixD(beamSpotCov) + longerrorRotated;
 
  // Standard algorithm needs no shift
  ROOT::Math::XYZVector constraintCenter = m_BeamSpotCenter;
 
  return make_pair(constraintCenter, toSymMatrix(Tube));
}

static double getProperLifeTime(const MCParticle* mc)
{
  double beta = mc->getMomentum().R() / mc->getEnergy();
  return 1e3 * mc->getLifetime() * sqrt(1 - pow(beta, 2));
}
 
void TagVertexModule::BtagMCVertex(const Particle* Breco)
{
  //fill vector with mcB (intended order: Reco, Tag)
  vector<const MCParticle*> mcBs;
  for (const MCParticle& mc : m_mcParticles) {
    if (abs(mc.getPDG()) == abs(Breco->getPDGCode()))
      mcBs.push_back(&mc);
  }
  //too few Bs
  if (mcBs.size() < 2) return;
 
  if (mcBs.size() > 2) {
    B2WARNING("TagVertexModule:: Too many Bs found in MC");
  }
 
  auto isReco = [&](const MCParticle * mc) {
    return (m_useMCassociation == "breco") ? (mc == Breco->getRelated<MCParticle>())
           : compBrecoBgen(Breco, mc);  //internal association
  };
 
  //nothing matched?
  if (!isReco(mcBs[0]) && !isReco(mcBs[1])) {
    return;
  }
 
  //first is Tag, second Reco -> swap the order
  if (!isReco(mcBs[0]) && isReco(mcBs[1]))
    swap(mcBs[0], mcBs[1]);
 
  //both matched -> use closest vertex dist as Reco
  if (isReco(mcBs[0]) && isReco(mcBs[1])) {
    double dist0 = (mcBs[0]->getDecayVertex() - Breco->getVertex()).Mag2();
    double dist1 = (mcBs[1]->getDecayVertex() - Breco->getVertex()).Mag2();
    if (dist0 > dist1)
      swap(mcBs[0], mcBs[1]);
  }
 
  m_mcVertReco = mcBs[0]->getDecayVertex();
  m_mcLifeTimeReco  = getProperLifeTime(mcBs[0]);
  m_mcTagV = mcBs[1]->getDecayVertex();
  m_mcTagLifeTime = getProperLifeTime(mcBs[1]);
  m_mcPDG = mcBs[1]->getPDG();
}
 
// static
bool TagVertexModule::compBrecoBgen(const Particle* Breco, const MCParticle* Bgen)
{
 
  bool isDecMode = true;
 
  const std::vector<Particle*> recDau = Breco->getDaughters();
  const std::vector<MCParticle*> genDau = Bgen->getDaughters();
 
  if (recDau.size() > 0 && genDau.size() > 0) {
    for (auto dauRec : recDau) {
      bool isDau = false;
      for (auto dauGen : genDau) {
        if (dauGen->getPDG() == dauRec->getPDGCode())
          isDau = compBrecoBgen(dauRec, dauGen) ;
      }
      if (!isDau) isDecMode = false;
    }
  } else {
    if (recDau.size() == 0) { //&& genDau.size()==0){
      if (Bgen->getPDG() != Breco->getPDGCode()) isDecMode = false;;
    } else {isDecMode = false;}
  }
 
  return isDecMode;
}
 
// STANDARD FIT ALGORITHM
/* This algorithm basically takes all the tracks coming from the Rest Of Events and send them to perform a multi-track fit
 The option to request PXD hits for the tracks can be chosen by the user.
 */
std::vector<const Particle*> TagVertexModule::getTagTracks_standardAlgorithm(const Particle* Breco, int reqPXDHits) const
{
  std::vector<const Particle*> fitParticles;
  const RestOfEvent* roe = Breco->getRelatedTo<RestOfEvent>();
  if (!roe) return fitParticles;
  //load all particles from the ROE
  std::vector<const Particle*> ROEParticles = roe->getChargedParticles(m_roeMaskName, 0, false);
  if (ROEParticles.size() == 0) return fitParticles;
 
  for (auto& ROEParticle : ROEParticles) {
    HitPatternVXD roeTrackPattern = ROEParticle->getTrackFitResult()->getHitPatternVXD();
 
    if (roeTrackPattern.getNPXDHits() >= reqPXDHits) {
      fitParticles.push_back(ROEParticle);
    }
  }
  return fitParticles;
}
 
 
vector<ParticleAndWeight> TagVertexModule::getParticlesAndWeights(const vector<const Particle*>& tagParticles) const
{
  vector<ParticleAndWeight> particleAndWeights;
 
  for (const Particle* particle : tagParticles) {
    ROOT::Math::PxPyPzEVector mom = particle->get4Vector();
    if (!isfinite(mom.mag2())) continue;
 
    ParticleAndWeight particleAndWeight;
    particleAndWeight.mcParticle = 0;
    particleAndWeight.weight = -1111.;
    particleAndWeight.particle = particle;
 
    if (m_useMCassociation == "breco" || m_useMCassociation == "internal")
      particleAndWeight.mcParticle = particle->getRelatedTo<MCParticle>();
 
    particleAndWeights.push_back(particleAndWeight);
  }
 
  return particleAndWeights;
}
 
bool TagVertexModule::makeGeneralFit()
{
  if (m_fitAlgo == "Rave") return makeGeneralFitRave();
  else if (m_fitAlgo == "KFit") return makeGeneralFitKFit();
  return false;
}
 
void TagVertexModule::fillParticles(vector<ParticleAndWeight>& particleAndWeights)
{
  unsigned n = particleAndWeights.size();
  sort(particleAndWeights.begin(), particleAndWeights.end(),
  [](const ParticleAndWeight & a, const ParticleAndWeight & b) { return a.weight > b.weight; });
 
  m_raveParticles.resize(n);
  m_raveWeights.resize(n);
  m_raveMCParticles.resize(n);
 
  for (unsigned i = 0; i < n; ++i) {
    m_raveParticles.at(i) = particleAndWeights.at(i).particle;
    m_raveMCParticles.at(i) = particleAndWeights.at(i).mcParticle;
    m_raveWeights.at(i) = particleAndWeights.at(i).weight;
  }
}
 
void TagVertexModule::fillTagVinfo(const ROOT::Math::XYZVector& tagVpos, const TMatrixDSym& tagVposErr)
{
  m_tagV = tagVpos;
 
  if (m_constraintType != "noConstraint") {
    TMatrixDSym tubeInv = m_constraintCov;
    tubeInv.Invert();
    TVectorD dV = toVec(m_tagV - m_BeamSpotCenter);
    m_tagVChi2IP = tubeInv.Similarity(dV);
  }
 
  m_tagVErrMatrix.ResizeTo(tagVposErr);
  m_tagVErrMatrix = tagVposErr;
}
 
bool TagVertexModule::makeGeneralFitRave()
{
  // apply constraint
  analysis::RaveSetup::getInstance()->unsetBeamSpot();
  if (m_constraintType != "noConstraint")
    analysis::RaveSetup::getInstance()->setBeamSpot(m_constraintCenter, m_constraintCov);
  analysis::RaveVertexFitter rFit;
 
  //feed rave with tracks without Kshorts
  vector<ParticleAndWeight> particleAndWeights = getParticlesAndWeights(m_tagParticles);
 
  for (const auto& pw : particleAndWeights) {
    try {
      if (m_useTruthInFit) {
        if (pw.mcParticle) {
          TrackFitResult tfr(getTrackWithTrueCoordinates(pw));
          rFit.addTrack(&tfr);
        } else
          m_fitTruthStatus = 2;
      } else if (m_useRollBack) {
        if (pw.mcParticle) {
          TrackFitResult tfr(getTrackWithRollBackCoordinates(pw));
          rFit.addTrack(&tfr);
        } else
          m_rollbackStatus = 2;
      } else {
        rFit.addTrack(pw.particle->getTrackFitResult());
      }
    } catch (const rave::CheckedFloatException&) {
      B2ERROR("Exception caught in TagVertexModule::makeGeneralFitRave(): Invalid inputs (nan/inf)?");
    }
  }
 
  //perform fit
 
  int isGoodFit(-1);
 
  try {
    isGoodFit = rFit.fit("avf");
    // if problems
    if (isGoodFit < 1) return false;
  } catch (const rave::CheckedFloatException&) {
    B2ERROR("Exception caught in TagVertexModule::makeGeneralFitRave(): Invalid inputs (nan/inf)?");
    return false;
  }
 
  //save the track info for later use
 
  for (unsigned int i(0); i < particleAndWeights.size() && isGoodFit >= 1; ++i)
    particleAndWeights.at(i).weight = rFit.getWeight(i);
 
  //Tracks are sorted from highest rave weight to lowest
 
  fillParticles(particleAndWeights);
 
  //if the fit is good, save the infos related to the vertex
  fillTagVinfo(ROOT::Math::XYZVector(rFit.getPos(0)), rFit.getCov(0));
 
  //fill quality variables
  m_tagVNDF = rFit.getNdf(0);
  m_tagVChi2 = rFit.getChi2(0);
  m_fitPval = rFit.getPValue();
 
  return true;
}
 
 
analysis::VertexFitKFit TagVertexModule::doSingleKfit(vector<ParticleAndWeight>& particleAndWeights)
{
  //initialize KFit
  analysis::VertexFitKFit kFit;
  kFit.setMagneticField(m_Bfield);
 
  // apply constraint
  if (m_constraintType != "noConstraint") {
    if (m_constraintType == "tube") {
      CLHEP::HepSymMatrix err(7, 0);
      //copy m_pvCov to the end of err matrix
      err.sub(5, ROOTToCLHEP::getHepSymMatrix(m_pvCov));
      kFit.setIpTubeProfile(
        ROOTToCLHEP::getHepLorentzVector(m_tagMomentum),
        ROOTToCLHEP::getPoint3D(m_constraintCenter),
        err,
        0.);
    } else {
      kFit.setIpProfile(ROOTToCLHEP::getPoint3D(m_constraintCenter),
                        ROOTToCLHEP::getHepSymMatrix(m_constraintCov));
    }
  }
 
 
  for (auto& pawi : particleAndWeights) {
    int addedOK = 1;
    if (m_useTruthInFit) {
      if (pawi.mcParticle) {
        addedOK = kFit.addTrack(
                    ROOTToCLHEP::getHepLorentzVector(pawi.mcParticle->get4Vector()),
                    ROOTToCLHEP::getPoint3D(getTruePoca(pawi)),
                    ROOTToCLHEP::getHepSymMatrix(pawi.particle->getMomentumVertexErrorMatrix()),
                    pawi.particle->getCharge());
      } else {
        m_fitTruthStatus = 2;
      }
    } else if (m_useRollBack) {
      if (pawi.mcParticle) {
        addedOK = kFit.addTrack(
                    ROOTToCLHEP::getHepLorentzVector(pawi.mcParticle->get4Vector()),
                    ROOTToCLHEP::getPoint3D(getRollBackPoca(pawi)),
                    ROOTToCLHEP::getHepSymMatrix(pawi.particle->getMomentumVertexErrorMatrix()),
                    pawi.particle->getCharge());
      } else {
        m_rollbackStatus = 2;
      }
    } else {
      addedOK = kFit.addParticle(pawi.particle);
    }
 
    if (addedOK == 0) {
      pawi.weight = 1.;
    } else {
      B2WARNING("TagVertexModule::makeGeneralFitKFit: failed to add a track");
      pawi.weight = 0.;
    }
  }
 
 
  int nTracksAdded = kFit.getTrackCount();
 
  //perform fit if there are enough tracks
  if ((nTracksAdded < 2 && m_constraintType == "noConstraint") || nTracksAdded < 1)
    return  analysis::VertexFitKFit();
 
  int isGoodFit = kFit.doFit();
  if (isGoodFit != 0) return analysis::VertexFitKFit();
 
  return kFit;
}
 
 
static int getLargestChi2ID(const analysis::VertexFitKFit& kFit)
{
  int largest_chi2_trackid = -1;
  double largest_track_chi2 = -1;
  for (int i = 0; i < kFit.getTrackCount(); ++i) {
    double track_chi2 = kFit.getTrackCHIsq(i);
    if (track_chi2 > largest_track_chi2) {
      largest_track_chi2 = track_chi2;
      largest_chi2_trackid = i;
    }
  }
  return largest_chi2_trackid;
}
 
 
 
//uses m_tagMomentum, m_constraintCenter, m_constraintCov, m_tagParticles
bool TagVertexModule::makeGeneralFitKFit()
{
  //feed KFit with tracks without Kshorts
  vector<ParticleAndWeight> particleAndWeights = getParticlesAndWeights(m_tagParticles);
 
  analysis::VertexFitKFit kFit;
 
 
  // iterative procedure which removes tracks with high chi2
  for (int iteration_counter = 0; iteration_counter < 100; ++iteration_counter) {
    analysis::VertexFitKFit kFitTemp =  doSingleKfit(particleAndWeights);
    if (!kFitTemp.isFitted() || isnan(kFitTemp.getCHIsq()))
      return false;
 
    double reduced_chi2 =  kFitTemp.getCHIsq() / kFitTemp.getNDF();
    int nTracks = kFitTemp.getTrackCount();
 
    if (nTracks != int(particleAndWeights.size()))
      B2ERROR("TagVertexModule: Different number of tracks in kFit and particles");
 
    if (reduced_chi2 <= m_kFitReqReducedChi2 ||  nTracks <= 1  || (nTracks <= 2 && m_constraintType == "noConstraint")) {
      kFit = kFitTemp;
      break;
    } else { // remove particle with highest chi2/ndf and continue
      int badTrackID =  getLargestChi2ID(kFitTemp);
      if (0 <= badTrackID && badTrackID < int(particleAndWeights.size()))
        particleAndWeights.erase(particleAndWeights.begin() + badTrackID);
      else
        B2ERROR("TagVertexModule: Obtained badTrackID is not within limits");
    }
 
  }
 
  //save the track info for later use
  //Tracks are sorted by weight, i.e. pushing the tracks with 0 weight (from KS) to the end of the list
  fillParticles(particleAndWeights);
 
  //Save the infos related to the vertex
  fillTagVinfo(CLHEPToROOT::getXYZVector(kFit.getVertex()),
               CLHEPToROOT::getTMatrixDSym(kFit.getVertexError()));
 
  m_tagVNDF = kFit.getNDF();
  m_tagVChi2 = kFit.getCHIsq();
  m_fitPval = TMath::Prob(m_tagVChi2, m_tagVNDF);
 
  return true;
}
 
void TagVertexModule::deltaT(const Particle* Breco)
{
 
  ROOT::Math::XYZVector boost = PCmsLabTransform().getBoostVector();
  ROOT::Math::XYZVector boostDir = boost.Unit();
  double bg = boost.R() / sqrt(1 - boost.Mag2());
  double c = Const::speedOfLight / 1000.; // cm ps-1
 
  //Reconstructed DeltaL & DeltaT in the boost direction
  ROOT::Math::XYZVector dVert = Breco->getVertex() - m_tagV; //reconstructed vtxReco - vtxTag
  double dl = dVert.Dot(boostDir);
  m_deltaT  = dl / (bg * c);
 
  //Truth DeltaL & approx DeltaT in the boost direction
  ROOT::Math::XYZVector MCdVert = m_mcVertReco - m_mcTagV;   //truth vtxReco - vtxTag
  double MCdl = MCdVert.Dot(boostDir);
  m_mcDeltaT = MCdl / (bg * c);
 
  // MCdeltaTau=tauRec-tauTag
  m_mcDeltaTau = m_mcLifeTimeReco - m_mcTagLifeTime;
  if (m_mcLifeTimeReco  == -1 || m_mcTagLifeTime == -1)
    m_mcDeltaTau =  realNaN;
 
  TVectorD bVec = toVec(boostDir);
 
  //TagVertex error in boost dir
  m_tagVlErr = sqrt(m_tagVErrMatrix.Similarity(bVec));
 
  //bReco error in boost dir
  double bRecoErrL = sqrt(Breco->getVertexErrorMatrix().Similarity(bVec));
 
  //Delta t error
  m_deltaTErr =  hypot(m_tagVlErr, bRecoErrL) / (bg * c);
 
  m_tagVl = m_tagV.Dot(boostDir);
  m_truthTagVl = m_mcTagV.Dot(boostDir);
 
  // calculate tagV component and error in the direction orthogonal to the boost
  ROOT::Math::XYZVector oboost = getUnitOrthogonal(boostDir);
  TVectorD oVec = toVec(oboost);
 
  //TagVertex error in boost-orthogonal dir
  m_tagVolErr = sqrt(m_tagVErrMatrix.Similarity(oVec));
 
  m_tagVol = m_tagV.Dot(oboost);
  m_truthTagVol = m_mcTagV.Dot(oboost);
}
 
Particle* TagVertexModule::doVertexFitForBTube(const Particle* motherIn, const std::string& fitType) const
{
  //make a copy of motherIn to not modify the original object
  Particle* mother = ParticleCopy::copyParticle(motherIn);
 
  //Here rave is used to find the upsilon(4S) vtx as the intersection
  //between the mother B trajectory and the beam spot
  analysis::RaveSetup::getInstance()->setBeamSpot(m_BeamSpotCenter, m_BeamSpotCov);
 
  analysis::RaveVertexFitter rsg;
  rsg.addTrack(mother);
  int nvert = rsg.fit(fitType);
  if (nvert != 1) {
    mother->setPValue(-1); //error
    return mother;
  } else {
    rsg.updateDaughters();
    return mother;
  }
}
 
 
 
TrackFitResult TagVertexModule::getTrackWithTrueCoordinates(ParticleAndWeight const& paw) const
{
  if (!paw.mcParticle) {
    B2ERROR("In TagVertexModule::getTrackWithTrueCoordinate: no MC particle set");
    return TrackFitResult();
  }
 
  const TrackFitResult* tfr(paw.particle->getTrackFitResult());
 
  return TrackFitResult(getTruePoca(paw),
                        paw.mcParticle->getMomentum(),
                        tfr->getCovariance6(),
                        tfr->getChargeSign(),
                        tfr->getParticleType(),
                        tfr->getPValue(),
                        m_Bfield, 0, 0, tfr->getNDF());
}
 
// static
ROOT::Math::XYZVector TagVertexModule::getTruePoca(ParticleAndWeight const& paw)
{
  if (!paw.mcParticle) {
    B2ERROR("In TagVertexModule::getTruePoca: no MC particle set");
    return ROOT::Math::XYZVector(0., 0., 0.);
  }
 
  return DistanceTools::poca(paw.mcParticle->getProductionVertex(),
                             paw.mcParticle->getMomentum(),
                             paw.particle->getTrackFitResult()->getPosition());
}
 
TrackFitResult TagVertexModule::getTrackWithRollBackCoordinates(ParticleAndWeight const& paw)
{
  const TrackFitResult* tfr(paw.particle->getTrackFitResult());
 
  return TrackFitResult(getRollBackPoca(paw),
                        tfr->getMomentum(),
                        tfr->getCovariance6(),
                        tfr->getChargeSign(),
                        tfr->getParticleType(),
                        tfr->getPValue(),
                        m_Bfield, 0, 0, tfr->getNDF());
}
 
ROOT::Math::XYZVector TagVertexModule::getRollBackPoca(ParticleAndWeight const& paw)
{
  if (!paw.mcParticle) {
    B2ERROR("In TagVertexModule::getTruePoca: no MC particle set");
    return ROOT::Math::XYZVector(0., 0., 0.);
  }
 
  return paw.particle->getTrackFitResult()->getPosition() - paw.mcParticle->getProductionVertex() + m_mcTagV;
}
 
void TagVertexModule::resetReturnParams()
{
  m_raveParticles.resize(0);
  m_raveMCParticles.resize(0);
  m_tagParticles.resize(0);
  m_raveWeights.resize(0);
 
  m_fitPval = realNaN;
  m_tagV = vecNaN;
  m_tagVErrMatrix.ResizeTo(matNaN);
  m_tagVErrMatrix = matNaN;
  m_mcTagV = vecNaN;
  m_mcVertReco = vecNaN;
  m_deltaT = realNaN;
  m_deltaTErr = realNaN;
  m_mcDeltaTau = realNaN;
  m_constraintCov.ResizeTo(matNaN);
  m_constraintCov = matNaN;
  m_constraintCenter = vecNaN;
  m_tagVl = realNaN;
  m_truthTagVl = realNaN;
  m_tagVlErr = realNaN;
  m_tagVol = realNaN;
  m_truthTagVol = realNaN;
  m_tagVolErr = realNaN;
  m_tagVNDF = realNaN;
  m_tagVChi2 = realNaN;
  m_tagVChi2IP = realNaN;
  m_pvCov.ResizeTo(matNaN);
  m_pvCov = matNaN;
  m_tagMomentum = ROOT::Math::PxPyPzEVector(realNaN, realNaN, realNaN, realNaN);
}
 
//The following functions are just here to help printing stuff
 
// static
std::string TagVertexModule::printVector(const ROOT::Math::XYZVector& vec)
{
  std::ostringstream oss;
  int w = 14;
  oss << "(" << std::setw(w) << vec.X() << ", " << std::setw(w) << vec.Y() << ", " << std::setw(w) << vec.Z() << ")" << std::endl;
  return oss.str();
}
 
// static
std::string TagVertexModule::printMatrix(const TMatrixD& mat)
{
  std::ostringstream oss;
  int w = 14;
  for (int i = 0; i < mat.GetNrows(); ++i) {
    for (int j = 0; j < mat.GetNcols(); ++j) {
      oss << std::setw(w) << mat(i, j) << " ";
    }
    oss << endl;
  }
  return oss.str();
}
 
// static
std::string TagVertexModule::printMatrix(const TMatrixDSym& mat)
{
  std::ostringstream oss;
  int w = 14;
  for (int i = 0; i < mat.GetNrows(); ++i) {
    for (int j = 0; j < mat.GetNcols(); ++j) {
      oss << std::setw(w) << mat(i, j) << " ";
    }
    oss << endl;
  }
  return oss.str();
}