VZeroFinder Class Reference

#include <VZeroFinder.h>

Public Member Functions
bool	checkTrackPair (const reco::Track &posTrack, const reco::Track &negTrack, const reco::VertexCollection *vertices, reco::VZeroData &data)
GlobalVector	rotate (const GlobalVector &p, double a)
	VZeroFinder (const edm::EventSetup &es, const edm::ParameterSet &pset)
	~VZeroFinder ()

Private Member Functions
GlobalTrajectoryParameters	getGlobalTrajectoryParameters (const reco::Track &track)

Private Attributes
float	maxCrossingRadius
float	maxDca
float	maxImpactMother
float	minCrossingRadius
const MagneticField *	theMagField

Detailed Description

Definition at line 22 of file VZeroFinder.h.

Constructor & Destructor Documentation

VZeroFinder::VZeroFinder	(	const edm::EventSetup &	es,
		const edm::ParameterSet &	pset
	)

Definition at line 12 of file VZeroFinder.cc.

References edm::EventSetup::get(), and edm::ParameterSet::getParameter().

{
  // Get track-pair level cuts
  maxDca = pset.getParameter<double>("maxDca");

  // Get mother cuts
  minCrossingRadius = pset.getParameter<double>("minCrossingRadius");
  maxCrossingRadius = pset.getParameter<double>("maxCrossingRadius");
  maxImpactMother   = pset.getParameter<double>("maxImpactMother");

  // Get magnetic field
  edm::ESHandle<MagneticField> magField;
  es.get<IdealMagneticFieldRecord>().get(magField);
  theMagField = magField.product();
}

VZeroFinder::~VZeroFinder

(

)

Definition at line 30 of file VZeroFinder.cc.

{
}

Member Function Documentation

bool VZeroFinder::checkTrackPair	(	const reco::Track &	posTrack,
		const reco::Track &	negTrack,
		const reco::VertexCollection *	vertices,
		reco::VZeroData &	data
	)

Definition at line 60 of file VZeroFinder.cc.

References alpha, reco::VZeroData::armenterosAlpha, reco::VZeroData::armenterosPt, b, begin, reco::VZeroData::crossingPoint, reco::VZeroData::dca, getGlobalTrajectoryParameters(), reco::VZeroData::impactMother, PV3DBase< T, PVType, FrameType >::mag(), mag(), PV3DBase< T, PVType, FrameType >::mag2(), maxCrossingRadius, maxDca, maxImpactMother, minCrossingRadius, reco::VZeroData::momenta, GlobalTrajectoryParameters::momentum(), AlCaHLTBitMon_ParallelJobs::p, PV3DBase< T, PVType, FrameType >::perp(), alignCSCRings::r, rotate(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by VZeroProducer::produce().

{
/*
  LogTrace("MinBiasTracking") << " [VZeroFinder] tracks"
   << " +" << posTrack.algoName() << " " << posTrack.d0()
   << " -" << negTrack.algoName() << " " << negTrack.d0();
*/

  // Get trajectories
  GlobalTrajectoryParameters posGtp = getGlobalTrajectoryParameters(posTrack);
  GlobalTrajectoryParameters negGtp = getGlobalTrajectoryParameters(negTrack);

  // Two track minimum distance
  TwoTrackMinimumDistance theMinimum(TwoTrackMinimumDistance::SlowMode);

  // Closest approach
  theMinimum.calculate(posGtp,negGtp);

  // Closest points
  // std::pair<GlobalPoint, GlobalPoint> points = theMinimum.points();

  // Momenta at closest point
  std::pair<GlobalVector,GlobalVector> momenta;
  momenta.first  = rotate(posGtp.momentum(), theMinimum.firstAngle() );
  momenta.second = rotate(negGtp.momentum(), theMinimum.secondAngle());

  // dcaR
  float dca            = theMinimum.distance();
  GlobalPoint crossing = theMinimum.crossingPoint();

/*
  LogTrace("MinBiasTracking") << fixed << setprecision(2)
    << "  [VZeroFinder] dca    = "<<dca<<" (<"<<maxDca<<")";
  LogTrace("MinBiasTracking") << fixed << setprecision(2)
    << "  [VZeroFinder] crossR = "<<crossing.perp()<<" ("
    <<minCrossingRadius<<"< <"<<maxCrossingRadius<<")";
*/

  if(dca < maxDca &&
     crossing.perp() > minCrossingRadius &&
     crossing.perp() < maxCrossingRadius)
  {
    // Momentum of the mother
    GlobalVector momentum = momenta.first + momenta.second;
    float impact = -1.;

    if(vertices->size() > 0)
    {
      // Impact parameter of the mother wrt vertices, choose smallest
      for(reco::VertexCollection::const_iterator
          vertex = vertices->begin(); vertex!= vertices->end(); vertex++)
      {
        GlobalVector r(crossing.x(),
                       crossing.y(),
                       crossing.z() - vertex->position().z());
        GlobalVector p(momentum.x(),momentum.y(),momentum.z());
  
        GlobalVector b = r - (r*p)*p / p.mag2();
  
        float im = b.mag();
        if(im < impact || vertex == vertices->begin())
          impact = im; 
      }
    }
    else
    {
      // Impact parameter of the mother in the plane
      GlobalVector r_(crossing.x(),crossing.y(),0);
      GlobalVector p_(momentum.x(),momentum.y(),0);

      GlobalVector b_ = r_ - (r_*p_)*p_ / p_.mag2();
      impact = b_.mag(); 
    }

/*
    LogTrace("MinBiasTracking") << fixed << setprecision(2)
      << "  [VZeroFinder] impact = "<<impact<<" (<"<<maxImpactMother<<")";
*/

    if(impact < maxImpactMother)
    {
      // Armenteros variables
      float pt =
        (momenta.first.cross(momenta.second)).mag()/momentum.mag();
      float alpha =
        (momenta.first.mag2() - momenta.second.mag2())/momentum.mag2();

      // Fill data
      data.dca             = dca;
      data.crossingPoint   = crossing;
      data.impactMother    = impact;
      data.armenterosPt    = pt;
      data.armenterosAlpha = alpha;
      data.momenta         = momenta;

/*
      LogTrace("MinBiasTracking") << fixed << setprecision(2)
      << "  [VZeroFinder] success {alpha = "<<alpha<<", pt = "<<pt<<"}";
*/

      return true;
    }
  }

  return false;
}

GlobalTrajectoryParameters VZeroFinder::getGlobalTrajectoryParameters ( const reco::Track &  track )

private

Definition at line 36 of file VZeroFinder.cc.

References reco::TrackBase::charge(), reco::TrackBase::momentum(), position, and reco::TrackBase::vertex().

Referenced by checkTrackPair().

{
  GlobalPoint position(track.vertex().x(),
                       track.vertex().y(),
                       track.vertex().z());

  GlobalVector momentum(track.momentum().x(),
                        track.momentum().y(),
                        track.momentum().z());

  GlobalTrajectoryParameters gtp(position,momentum,
                                 track.charge(),theMagField);

  return gtp;
}

GlobalVector VZeroFinder::rotate	(	const GlobalVector &	p,
		double	a
	)

Definition at line 53 of file VZeroFinder.cc.

References funct::cos(), PV3DBase< T, PVType, FrameType >::perp(), funct::sin(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by checkTrackPair().

{
  double pt = p.perp();
  return GlobalVector( -pt*cos(a), -pt*sin(a), p.z());
}

Member Data Documentation

float VZeroFinder::maxCrossingRadius

private

Definition at line 38 of file VZeroFinder.h.

Referenced by checkTrackPair().

float VZeroFinder::maxDca

private

Definition at line 38 of file VZeroFinder.h.

Referenced by checkTrackPair().

float VZeroFinder::maxImpactMother

private

Definition at line 38 of file VZeroFinder.h.

Referenced by checkTrackPair().

float VZeroFinder::minCrossingRadius

private

Definition at line 38 of file VZeroFinder.h.

Referenced by checkTrackPair().

const MagneticField* VZeroFinder::theMagField

private

Definition at line 43 of file VZeroFinder.h.