Kpi.cxx

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//
//  Kpi.cxx is the single D0 tag code to reconstruct D0 or anti-D0 through the final states of
//  Kpi from D0 decays. Kpi.cxx was transfered from the Fortran routine "Kpi.f" which was
//  orignally used for study of the D0D0-bar production and D0 decays at the BES-II
//  experiment during the time period from 2002 to 2008.
//
//  The orignal Fortran routine "Kpi.f" used at the BES-II experiment was coded by G. Rong in
//  2001.
//
//  Kpi.cxx was transfered by G. Rong and J. Liu in December, 2005.
//
//  Since 2008, G. Rong and L.L. Jiang have been working on developing this code to analyze of
//  the data taken at 3.773 GeV with the BES-III detector at the BEPC-II collider.
//
//  During developing this code, many People made significant contributions to this code. These
//  are
//          G. Rong, L.L. Jiang, J. Liu, H.L. Ma, J.C. Chen, D.H. Zhang,
//          M.G. Zhao, B. Zheng, L. Li, Y. Fang, Z.Y. Yi, H.H. Liu, Z.Q. Liu et al.
//
//                                       By G. Rong and L.L. Jiang
//                                       March, 2009
//
//  ==========================================================================================
//
#include "SD0TagAlg/Kpi.h"
#include "SD0TagAlg/SingleBase.h"
 
Kpi::Kpi() {}
 
Kpi::~Kpi() {}
 
void Kpi::MTotal( double event, SmartDataPtr<EvtRecTrackCol> evtRecTrkCol, Vint iGood,
                  Vint iGam, double Ebeam, int PID_flag, int Charge_candidate_D ) {
 
  int nGood = iGood.size();
  int nGam  = iGam.size();
 
  iGoodtag.clear();
  iGamtag.clear();
 
  double           mass_bcgg, delE_tag_temp;
  int              m_chargetag, m_chargek, m_chargepi;
  int              ika_temp, ipi_temp, ipi2_temp, ipi3_temp;
  HepLorentzVector kmfit1, kmfit2, kmfit3, kmfit4, pddd;
 
  int               cqtm_temp;
  HepLorentzVector  pddd_temp;
  IDataProviderSvc* eventSvc = NULL;
  Gaudi::svcLocator()->service( "EventDataSvc", eventSvc );
  SmartDataPtr<EvtRecEvent>        evtRecEvent( eventSvc, EventModel::EvtRec::EvtRecEvent );
  SmartDataPtr<Event::EventHeader> eventHeader( eventSvc, "/Event/EventHeader" );
 
  int runNo = eventHeader->runNumber();
  int rec   = eventHeader->eventNumber();
 
  double xecm = 2 * Ebeam;
 
  kpimd          = false;
  double tagmode = 0;
 
  if ( ( evtRecEvent->totalCharged() < 2 ) ) { return; }
 
  double ecms = xecm;
  ;
 
  ISimplePIDSvc* simple_pid;
  Gaudi::svcLocator()->service( "SimplePIDSvc", simple_pid );
 
  double deltaE_tem = 0.20;
  int    ncount1    = 0;
 
  Hep3Vector    xorigin( 0, 0, 0 );
  IVertexDbSvc* vtxsvc;
  Gaudi::svcLocator()->service( "VertexDbSvc", vtxsvc );
  if ( vtxsvc->isVertexValid() )
  {
    double* dbv = vtxsvc->PrimaryVertex();
    double* vv  = vtxsvc->SigmaPrimaryVertex();
    xorigin.setX( dbv[0] );
    xorigin.setY( dbv[1] );
    xorigin.setZ( dbv[2] );
  }
 
  double xv = xorigin.x();
  double yv = xorigin.y();
  double zv = xorigin.z();
 
  HepPoint3D point0( 0., 0., 0. );
  HepPoint3D IP( xorigin[0], xorigin[1], xorigin[2] );
 
  HepLorentzVector ptrk1_temp, ptrk2_temp;
  //////////////////////////////////////////////////////////////////
  for ( int i = 0; i < evtRecEvent->totalCharged(); i++ )
  {
    EvtRecTrackIterator itTrk = evtRecTrkCol->begin() + i;
 
    int ika = ( *itTrk )->trackId();
 
    if ( !( *itTrk )->isMdcKalTrackValid() ) continue;
    RecMdcKalTrack* mdcKalTrk1 = ( *itTrk )->mdcKalTrack();
    RecMdcKalTrack::setPidType( RecMdcKalTrack::kaon );
    /////////////////////////////////////////
    m_chargek = mdcKalTrk1->charge();
    if ( Charge_candidate_D != 0 )
    {
      if ( m_chargek != -Charge_candidate_D ) continue;
    }
    if ( Charge_candidate_D == 0 )
    {
      if ( abs( m_chargek ) != 1 ) continue;
    }
    /////////////////////////////////////////
    HepVector    a1  = mdcKalTrk1->getZHelixK();
    HepSymMatrix Ea1 = mdcKalTrk1->getZErrorK();
    VFHelix      helixip3_1( point0, a1, Ea1 );
    helixip3_1.pivot( IP );
    HepVector vecipa1 = helixip3_1.a();
 
    double dr1       = fabs( vecipa1[0] );
    double dz1       = fabs( vecipa1[3] );
    double costheta1 = cos( mdcKalTrk1->theta() );
    if ( dr1 >= 1.0 ) continue;
    if ( dz1 >= 10.0 ) continue;
    if ( fabs( costheta1 ) >= 0.93 ) continue;
    /////////////////////////////////////////
    if ( PID_flag == 5 )
    {
      simple_pid->preparePID( *itTrk );
      if ( simple_pid->probKaon() < 0.0 || simple_pid->probKaon() < simple_pid->probPion() )
        continue;
    }
    /////////////////////////////////////////
 
    WTrackParameter kam( xmass[3], mdcKalTrk1->getZHelixK(), mdcKalTrk1->getZErrorK() );
 
    //
    // select pi
    //
    for ( int j = 0; j < evtRecEvent->totalCharged(); j++ )
    {
      EvtRecTrackIterator itTrk = evtRecTrkCol->begin() + j;
 
      int ipi = ( *itTrk )->trackId();
      if ( ipi == ika ) continue;
 
      if ( !( *itTrk )->isMdcKalTrackValid() ) continue;
      RecMdcKalTrack* mdcKalTrk2 = ( *itTrk )->mdcKalTrack();
      RecMdcKalTrack::setPidType( RecMdcKalTrack::pion );
 
      /////////////////////////////////////////
      m_chargepi = mdcKalTrk2->charge();
      if ( ( m_chargek + m_chargepi ) != 0 ) continue;
      /////////////////////////////////////////
      HepVector    a2  = mdcKalTrk2->getZHelix();
      HepSymMatrix Ea2 = mdcKalTrk2->getZError();
      VFHelix      helixip3_2( point0, a2, Ea2 );
      helixip3_2.pivot( IP );
      HepVector vecipa2 = helixip3_2.a();
 
      double dr2       = fabs( vecipa2[0] );
      double dz2       = fabs( vecipa2[3] );
      double costheta2 = cos( mdcKalTrk2->theta() );
      if ( dr2 >= 1.0 ) continue;
      if ( dz2 >= 10.0 ) continue;
      if ( fabs( costheta2 ) >= 0.93 ) continue;
      /////////////////////////////////////////
      if ( PID_flag == 5 )
      {
        simple_pid->preparePID( *itTrk );
        if ( simple_pid->probPion() < 0.0 || simple_pid->probPion() < simple_pid->probKaon() )
          continue;
      }
      /////////////////////////////////////////
 
      WTrackParameter pip( xmass[2], mdcKalTrk2->getZHelix(), mdcKalTrk2->getZError() );
 
      //////////////////////////////////////////////////////////////
      HepPoint3D   vx( xorigin.x(), xorigin.y(), xorigin.z() );
      HepSymMatrix Evx( 3, 0 );
      double       bx = 1E+6;
      Evx[0][0]       = bx * bx;
      double by       = 1E+6;
      Evx[1][1]       = by * by;
      double bz       = 1E+6;
      Evx[2][2]       = bz * bz;
      VertexParameter vxpar;
      vxpar.setVx( vx );
      vxpar.setEvx( Evx );
      //////////////////////////////////////////////////////////////
 
      VertexFit* vtxfit = VertexFit::instance();
      vtxfit->init();
      vtxfit->AddTrack( 0, kam );
      vtxfit->AddTrack( 1, pip );
      vtxfit->AddVertex( 0, vxpar, 0, 1 );
      if ( !vtxfit->Fit( 0 ) ) continue;
      vtxfit->Swim( 0 );
 
      WTrackParameter wkam = vtxfit->wtrk( 0 );
      WTrackParameter wpip = vtxfit->wtrk( 1 );
 
      HepVector kam_val = HepVector( 7, 0 );
      kam_val           = wkam.w();
      HepVector pip_val = HepVector( 7, 0 );
      pip_val           = wpip.w();
 
      HepLorentzVector P_KAM( kam_val[0], kam_val[1], kam_val[2], kam_val[3] );
      HepLorentzVector P_PIP( pip_val[0], pip_val[1], pip_val[2], pip_val[3] );
 
      P_KAM.boost( -0.011, 0, 0 );
      P_PIP.boost( -0.011, 0, 0 );
      pddd = P_KAM + P_PIP;
 
      double pkpi = pddd.rho();
 
      double temp1 = ( ecms / 2 ) * ( ecms / 2 ) - pkpi * pkpi;
      if ( temp1 < 0 ) temp1 = 0;
      double mass_bc_tem = sqrt( temp1 );
 
      if ( mass_bc_tem < 1.82 || mass_bc_tem > 1.89 ) continue;
 
      double delE_tag_tag = ecms / 2 - pddd.e();
 
      if ( fabs( delE_tag_tag ) < deltaE_tem )
      {
        deltaE_tem    = fabs( delE_tag_tag );
        delE_tag_temp = delE_tag_tag;
        mass_bcgg     = mass_bc_tem;
 
        pddd_temp = pddd;
        cqtm_temp = m_chargek;
        ika_temp  = ika;
        ipi_temp  = ipi;
        ncount1   = 1;
      }
    }
  }
 
  if ( ncount1 == 1 )
  {
    tagmode = 11;
    if ( cqtm_temp < 0 ) tagmode = -11;
    tagmd    = tagmode;
    mass_bc  = mass_bcgg;
    delE_tag = delE_tag_temp;
    cqtm     = -1.0 * cqtm_temp;
 
    // cqtm = +1 for D0-->K-Pi+; cqtm = -1 for D0-bar-->K+Pi-;
    // cqtm = 0 for D0-->K+K- ect. ...; cqtm = 0 means that we do not
    // know whether it s D0 or D0-bar decays;
 
    iGoodtag.push_back( ika_temp );
    iGoodtag.push_back( ipi_temp );
 
    iGamtag.push_back( 9999 );
    iGamtag.push_back( 9999 );
    iGamtag.push_back( 9999 );
    iGamtag.push_back( 9999 );
 
    ptag = pddd_temp;
 
    kpimd = true;
  }
}