LocalKsSelector.cxx

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#include "GaudiKernel/Bootstrap.h"
#include "GaudiKernel/ISvcLocator.h"
 
#include "EvtRecEvent/EvtRecVeeVertex.h"
#include "LocalKsSelector.h"
#include "VertexDbSvc/IVertexDbSvc.h"
#include "VertexFit/SecondVertexFit.h"
#include "VertexFit/VertexFit.h"
#include "VertexFitRefine/VertexFitRefine.h"
 
DECLARE_COMPONENT( LocalKsSelector )
 
LocalKsSelector::LocalKsSelector( const std::string& type, const std::string& name,
                                  const IInterface* parent )
    : base_class( type, name, parent ) {
  declareProperty( "KsMinMassCut", m_minMass = 0.470 );
  declareProperty( "KsMaxMassCut", m_maxMass = 0.528 );
  declareProperty( "KsMaxChisq", m_maxChisq = 100 );
 
  declareProperty( "DoSecondaryVFit", m_doSecondaryVFit = false );
  declareProperty( "KsMaxVFitChisq", m_maxVFitChisq = 100 );
  declareProperty( "KsMinFlightSig", m_minFlightSig = 2.0 );
  declareProperty( "UseVFRefine", m_useVFrefine = true );
 
  declareProperty( "UseBFieldCorr", m_useBFC = true );
}
 
bool LocalKsSelector::operator()( CDKs& aKs ) {
 
  aKs.setUserTag( 1 );
  EvtRecVeeVertex* ks = const_cast<EvtRecVeeVertex*>( aKs.navKshort() );
 
  if ( ks->vertexId() != 310 ) return false;
 
  if ( !m_useBFC )
  {
    double mass = ks->mass();
    if ( ( mass <= m_minMass ) || ( mass >= m_maxMass ) ) return false;
    if ( ks->chi2() >= m_maxChisq ) return false;
 
    if ( !m_doSecondaryVFit ) return true;
  }
 
  // --------------------------------------------------
  // Do a secondary vertex fit and check the flight significance
  // --------------------------------------------------
 
  EvtRecTrack*    veeTrack1    = ks->pairDaughters().first;
  RecMdcKalTrack* veeKalTrack1 = veeTrack1->mdcKalTrack();
  veeKalTrack1->setPidType( RecMdcKalTrack::pion );
  WTrackParameter veeInitialWTrack1 =
      WTrackParameter( 0.13957018, veeKalTrack1->getZHelix(), veeKalTrack1->getZError() );
 
  EvtRecTrack*    veeTrack2    = ks->pairDaughters().second;
  RecMdcKalTrack* veeKalTrack2 = veeTrack2->mdcKalTrack();
  veeKalTrack2->setPidType( RecMdcKalTrack::pion );
  WTrackParameter veeInitialWTrack2 =
      WTrackParameter( 0.13957018, veeKalTrack2->getZHelix(), veeKalTrack2->getZError() );
 
  // VertexParameter wideVertex;
  HepPoint3D   vWideVertex( 0., 0., 0. );
  HepSymMatrix evWideVertex( 3, 0 );
 
  evWideVertex[0][0] = 1.0e12;
  evWideVertex[1][1] = 1.0e12;
  evWideVertex[2][2] = 1.0e12;
 
  // add the primary vertex
  HepPoint3D   vBeamSpot( 0., 0., 0. );
  HepSymMatrix evBeamSpot( 3, 0 );
 
  IVertexDbSvc* vtxsvc;
  StatusCode    sc = serviceLocator()->service( "VertexDbSvc", vtxsvc );
  if ( vtxsvc->isVertexValid() )
  {
    double* dbv = vtxsvc->PrimaryVertex();
    double* vv  = vtxsvc->SigmaPrimaryVertex();
    for ( unsigned int ivx = 0; ivx < 3; ivx++ )
    {
      vBeamSpot[ivx]       = dbv[ivx];
      evBeamSpot[ivx][ivx] = vv[ivx] * vv[ivx];
    }
  }
  else
  {
    cout << "KSSELECTOR ERROR:  Could not find a vertex from VertexDbSvc" << endl;
    return false;
  }
 
  if ( m_useVFrefine )
  {
 
    VertexParameter wideVertex;
 
    wideVertex.setVx( vWideVertex );
    wideVertex.setEvx( evWideVertex );
 
    // First, perform a vertex fit refine
    VertexFitRefine* vtxfitr = VertexFitRefine::instance();
    vtxfitr->init();
 
    vtxfitr->AddTrack( 0, veeKalTrack1, RecMdcKalTrack::pion );
    vtxfitr->AddTrack( 1, veeKalTrack2, RecMdcKalTrack::pion );
    vtxfitr->AddVertex( 0, wideVertex, 0, 1 );
 
    bool fitok = vtxfitr->Fit();
 
    HepLorentzVector ppi1 = vtxfitr->pfit( 0 );
    HepLorentzVector ppi2 = vtxfitr->pfit( 1 );
    HepLorentzVector pks  = ppi1 + ppi2;
 
    double mass     = pks.m();
    double chisqvtx = vtxfitr->chisq( 0 );
 
    if ( m_useBFC )
    {
      if ( ( mass <= m_minMass ) || ( mass >= m_maxMass ) ) return false;
      // if ( ks->chi2() >= m_maxChisq ) return false;
      if ( chisqvtx >= m_maxChisq ) return false;
 
      if ( !m_doSecondaryVFit ) return true;
    }
 
    // Now perform the secondary vertex fit
    SecondVertexFit* svtxfit = SecondVertexFit::instance();
    svtxfit->init();
 
    // add the primary vertex
    VertexParameter beamSpot;
 
    beamSpot.setVx( vBeamSpot );
    beamSpot.setEvx( evBeamSpot );
 
    VertexParameter primaryVertex( beamSpot );
    svtxfit->setPrimaryVertex( primaryVertex );
 
    // add the secondary vertex
    svtxfit->setVpar( vtxfitr->vpar( 0 ) );
 
    // add the Ks or lambda
    svtxfit->AddTrack( 0, vtxfitr->wVirtualTrack( 0 ) );
 
    // do the second vertex fit
    // if the fit fails, the default values will not be changed
    if ( !svtxfit->Fit() ) return false;
 
    // save the new ks parameters
    double vfitlength = svtxfit->decayLength();
    double vfiterror  = svtxfit->decayLengthError();
    double vfitchi2   = svtxfit->chisq();
    double flightsig  = 0;
    if ( vfiterror != 0 ) flightsig = vfitlength / vfiterror;
 
    // if the ks does not meet the criteria, the information from
    // the secondary vertex fit will not be filled (default = -999)
    if ( vfitchi2 > m_maxVFitChisq ) return false;
    if ( flightsig < m_minFlightSig ) return false;
 
    return true;
  }
  else
  {
    VertexParameter wideVertex;
 
    wideVertex.setVx( vWideVertex );
    wideVertex.setEvx( evWideVertex );
 
    // First, perform a vertex fit
    VertexFit* vtxfit = VertexFit::instance();
    vtxfit->init();
 
    // add the daughters
    vtxfit->AddTrack( 0, veeInitialWTrack1 );
    vtxfit->AddTrack( 1, veeInitialWTrack2 );
    vtxfit->AddVertex( 0, wideVertex, 0, 1 );
 
    // do the fit
    vtxfit->Fit( 0 );
    vtxfit->Swim( 0 );
    vtxfit->BuildVirtualParticle( 0 );
 
    WTrackParameter wks    = vtxfit->wVirtualTrack( 0 );
    WTrackParameter wkspi1 = vtxfit->wtrk( 0 );
    WTrackParameter wkspi2 = vtxfit->wtrk( 1 );
 
    HepLorentzVector pks = wks.p();
 
    double mass     = pks.m();
    double chisqvtx = vtxfit->chisq( 0 );
 
    if ( m_useBFC )
    {
      if ( ( mass <= m_minMass ) || ( mass >= m_maxMass ) ) return false;
      // if ( ks->chi2() >= m_maxChisq ) return false;
      if ( chisqvtx >= m_maxChisq ) return false;
 
      if ( !m_doSecondaryVFit ) return true;
    }
 
    // Now perform the secondary vertex fit
    SecondVertexFit* svtxfit = SecondVertexFit::instance();
    svtxfit->init();
 
    // add the primary vertex
    VertexParameter beamSpot;
 
    beamSpot.setVx( vBeamSpot );
    beamSpot.setEvx( evBeamSpot );
 
    VertexParameter primaryVertex( beamSpot );
    svtxfit->setPrimaryVertex( primaryVertex );
 
    // add the secondary vertex
    svtxfit->setVpar( vtxfit->vpar( 0 ) );
 
    // add the Ks or lambda
    svtxfit->AddTrack( 0, vtxfit->wVirtualTrack( 0 ) );
 
    // do the second vertex fit
    // if the fit fails, the default values will not be changed
    if ( !svtxfit->Fit() ) return false;
 
    // save the new ks parameters
    double vfitlength = svtxfit->decayLength();
    double vfiterror  = svtxfit->decayLengthError();
    double vfitchi2   = svtxfit->chisq();
    double flightsig  = 0;
    if ( vfiterror != 0 ) flightsig = vfitlength / vfiterror;
 
    // if the ks does not meet the criteria, the information from
    // the secondary vertex fit will not be filled (default = -999)
    if ( vfitchi2 > m_maxVFitChisq ) return false;
    if ( flightsig < m_minFlightSig ) return false;
 
    return true;
  }
}