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TwoBodyDecayLinearizationPointFinder Class Reference

Class TwoBodyDecayLinearizationPointFinder computes a rough estimate of the parameters of a decay. More...

#include <Alignment/TwoBodyDecay/interface/TwoBodyDecayLinearizationPointFinder.h>

List of all members.

Public Types

typedef
PerigeeLinearizedTrackState::RefCountedLinearizedTrackState 		RefCountedLinearizedTrackState

Public Member Functions

virtual
TwoBodyDecayLinearizationPointFinder * 		clone (void) const
virtual const
TwoBodyDecayParameters 		getLinearizationPoint (const std::vector< RefCountedLinearizedTrackState > &tracks, const double primaryMass, const double secondaryMass) const
 TwoBodyDecayLinearizationPointFinder (const edm::ParameterSet &config)
virtual ~TwoBodyDecayLinearizationPointFinder (void)

Detailed Description

Class TwoBodyDecayLinearizationPointFinder computes a rough estimate of the parameters of a decay.

This serves as linearization point for TwoBodyDecayEstimator.

/author Edmund Widl

Definition at line 16 of file TwoBodyDecayLinearizationPointFinder.h.

Member Typedef Documentation

typedef PerigeeLinearizedTrackState::RefCountedLinearizedTrackState TwoBodyDecayLinearizationPointFinder::RefCountedLinearizedTrackState

Definition at line 21 of file TwoBodyDecayLinearizationPointFinder.h.

Constructor & Destructor Documentation

TwoBodyDecayLinearizationPointFinder::TwoBodyDecayLinearizationPointFinder ( const edm::ParameterSet &  config  )  [inline]

Definition at line 23 of file TwoBodyDecayLinearizationPointFinder.h.

Referenced by clone().

00023 {}

virtual TwoBodyDecayLinearizationPointFinder::~TwoBodyDecayLinearizationPointFinder ( void   )  [inline, virtual]

Definition at line 25 of file TwoBodyDecayLinearizationPointFinder.h.

00025 {}

Member Function Documentation

virtual TwoBodyDecayLinearizationPointFinder* TwoBodyDecayLinearizationPointFinder::clone ( void   )  const [inline, virtual]

Definition at line 32 of file TwoBodyDecayLinearizationPointFinder.h.

References TwoBodyDecayLinearizationPointFinder().

00032 { return new TwoBodyDecayLinearizationPointFinder( *this ); }

const TwoBodyDecayParameters TwoBodyDecayLinearizationPointFinder::getLinearizationPoint ( const std::vector< RefCountedLinearizedTrackState > &  tracks,
const double  primaryMass,
const double  secondaryMass 
) const [virtual]

Definition at line 7 of file TwoBodyDecayLinearizationPointFinder.cc.

References TwoBodyDecayParameters::dimension, TwoBodyDecayParameters::mass, TrajectoryStateClosestToPoint::momentum(), p, p1, p2, TwoBodyDecayParameters::phi, pi, PerigeeLinearizedTrackState::predictedState(), TwoBodyDecayParameters::px, TwoBodyDecayParameters::py, TwoBodyDecayParameters::pz, TwoBodyDecayModel::rotationMatrix(), funct::sqrt(), TwoBodyDecayParameters::theta, PV3DBase< T, PVType, FrameType >::x(), TwoBodyDecayParameters::x, PV3DBase< T, PVType, FrameType >::y(), TwoBodyDecayParameters::y, PV3DBase< T, PVType, FrameType >::z(), and TwoBodyDecayParameters::z.

00010 {
00011   GlobalPoint linPoint = tracks[0]->linearizationPoint();
00012   PerigeeLinearizedTrackState* linTrack1 = dynamic_cast<PerigeeLinearizedTrackState*>( tracks[0].get() );
00013   GlobalVector firstMomentum = linTrack1->predictedState().momentum();
00014   PerigeeLinearizedTrackState* linTrack2 = dynamic_cast<PerigeeLinearizedTrackState*>( tracks[1].get() );
00015   GlobalVector secondMomentum = linTrack2->predictedState().momentum();
00016 
00017   AlgebraicVector secondaryMomentum1( 3 );
00018   secondaryMomentum1[0] = firstMomentum.x();
00019   secondaryMomentum1[1] = firstMomentum.y();
00020   secondaryMomentum1[2] = firstMomentum.z();
00021 
00022   AlgebraicVector secondaryMomentum2( 3 );
00023   secondaryMomentum2[0] = secondMomentum.x();
00024   secondaryMomentum2[1] = secondMomentum.y();
00025   secondaryMomentum2[2] = secondMomentum.z();
00026 
00027   AlgebraicVector primaryMomentum = secondaryMomentum1 + secondaryMomentum2;
00028 
00029   TwoBodyDecayModel decayModel( primaryMass, secondaryMass );
00030   AlgebraicMatrix rotMat = decayModel.rotationMatrix( primaryMomentum[0], primaryMomentum[1], primaryMomentum[2] );
00031   AlgebraicMatrix invRotMat = rotMat.T();
00032 
00033   double p = primaryMomentum.norm();
00034   double pSquared = p*p;
00035   double gamma = sqrt( pSquared + primaryMass*primaryMass )/primaryMass;
00036   double betaGamma = p/primaryMass;
00037   AlgebraicSymMatrix lorentzTransformation( 4, 1 );
00038   lorentzTransformation[0][0] = gamma;
00039   lorentzTransformation[3][3] = gamma;
00040   lorentzTransformation[0][3] = -betaGamma;
00041 
00042   double p1 = secondaryMomentum1.norm();
00043   AlgebraicVector boostedLorentzMomentum1( 4 );
00044   boostedLorentzMomentum1[0] = sqrt( p1*p1 + secondaryMass*secondaryMass );
00045   boostedLorentzMomentum1.sub( 2, invRotMat*secondaryMomentum1 );
00046 
00047   AlgebraicVector restFrameLorentzMomentum1 = lorentzTransformation*boostedLorentzMomentum1;
00048   AlgebraicVector restFrameMomentum1 = restFrameLorentzMomentum1.sub( 2, 4 );
00049   double perp1 = sqrt( restFrameMomentum1[0]*restFrameMomentum1[0] + restFrameMomentum1[1]*restFrameMomentum1[1] );
00050   double theta1 = atan2( perp1, restFrameMomentum1[2] );
00051   double phi1 = atan2( restFrameMomentum1[1], restFrameMomentum1[0] );
00052 
00053   double p2 = secondaryMomentum2.norm();
00054   AlgebraicVector boostedLorentzMomentum2( 4 );
00055   boostedLorentzMomentum2[0] = sqrt( p2*p2 + secondaryMass*secondaryMass );
00056   boostedLorentzMomentum2.sub( 2, invRotMat*secondaryMomentum2 );
00057 
00058   AlgebraicVector restFrameLorentzMomentum2 = lorentzTransformation*boostedLorentzMomentum2;
00059   AlgebraicVector restFrameMomentum2 = restFrameLorentzMomentum2.sub( 2, 4 );
00060   double perp2 = sqrt( restFrameMomentum2[0]*restFrameMomentum2[0] + restFrameMomentum2[1]*restFrameMomentum2[1] );
00061   double theta2 = atan2( perp2, restFrameMomentum2[2] );
00062   double phi2 = atan2( restFrameMomentum2[1], restFrameMomentum2[0] );
00063 
00064   double pi = 3.141592654;
00065   double relSign = -1.;
00066 
00067   if ( phi1 < 0 ) phi1 += 2*pi;
00068   if ( phi2 < 0 ) phi2 += 2*pi;
00069   if ( phi1 > phi2 ) relSign = 1.;
00070 
00071   double momentumSquared1 = secondaryMomentum1.normsq();
00072   double energy1 = sqrt( secondaryMass*secondaryMass + momentumSquared1 );
00073   double momentumSquared2 = secondaryMomentum2.normsq();
00074   double energy2 = sqrt( secondaryMass*secondaryMass + momentumSquared2 );
00075   double sumMomentaSquared = ( secondaryMomentum1 + secondaryMomentum2 ).normsq();
00076   double sumEnergiesSquared = ( energy1 + energy2 )*( energy1 + energy2 );
00077   double estimatedPrimaryMass = sqrt( sumEnergiesSquared - sumMomentaSquared );
00078 
00079   AlgebraicVector linParam( TwoBodyDecayParameters::dimension, 0 );
00080   linParam[TwoBodyDecayParameters::x] = linPoint.x();
00081   linParam[TwoBodyDecayParameters::y] = linPoint.y();
00082   linParam[TwoBodyDecayParameters::z] = linPoint.z();
00083   linParam[TwoBodyDecayParameters::px] = primaryMomentum[0];
00084   linParam[TwoBodyDecayParameters::py] = primaryMomentum[1];
00085   linParam[TwoBodyDecayParameters::pz] = primaryMomentum[2];
00086   linParam[TwoBodyDecayParameters::theta] = 0.5*( theta1 - theta2 + pi ) ;
00087   linParam[TwoBodyDecayParameters::phi] = 0.5*( phi1 + phi2 + relSign*pi );
00088   linParam[TwoBodyDecayParameters::mass] = estimatedPrimaryMass;
00089 
00090   return TwoBodyDecayParameters( linParam );
00091 }

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