TwoBodyDecayModel Class Reference

#include <TwoBodyDecayModel.h>

Public Member Functions
const std::pair < AlgebraicVector, AlgebraicVector >	cartesianSecondaryMomenta (const AlgebraicVector &param)
const std::pair < AlgebraicVector, AlgebraicVector >	cartesianSecondaryMomenta (const TwoBodyDecay &tbd)
const std::pair < AlgebraicVector, AlgebraicVector >	cartesianSecondaryMomenta (const TwoBodyDecayParameters &tbdparam)
AlgebraicVector	convertCurvilinearToCartesian (AlgebraicVector curv, double zMagField)
AlgebraicMatrix	curvilinearToCartesianJacobian (double rho, double theta, double phi, double zMagField)
AlgebraicMatrix	curvilinearToCartesianJacobian (AlgebraicVector curv, double zMagField)
AlgebraicMatrix	rotationMatrix (double px, double py, double pz)
	TwoBodyDecayModel (double mPrimary=91.1876, double mSecondary=0.105658)
	~TwoBodyDecayModel ()

Private Attributes
double	thePrimaryMass
double	theSecondaryMass

Detailed Description

/class TwoBodyDecayModel

This class provides useful methods needed for the two-body decay model used by implementations of e.g. class TwoBodyDecayEstimator or TwoBodyDecayLinearizationPointFinder.

/author Edmund Widl

Definition at line 16 of file TwoBodyDecayModel.h.

Constructor & Destructor Documentation

TwoBodyDecayModel::TwoBodyDecayModel	(	double	mPrimary = 91.1876,
		double	mSecondary = 0.105658
	)

Definition at line 5 of file TwoBodyDecayModel.cc.

                                                                         :
  thePrimaryMass( mPrimary ), theSecondaryMass( mSecondary ) {}

TwoBodyDecayModel::~TwoBodyDecayModel

(

)

Definition at line 9 of file TwoBodyDecayModel.cc.

{}

Member Function Documentation

const std::pair< AlgebraicVector, AlgebraicVector > TwoBodyDecayModel::cartesianSecondaryMomenta

(

const AlgebraicVector &

param

)

Momenta of the secondaries in cartesian repraesentation.

Definition at line 88 of file TwoBodyDecayModel.cc.

References alignmentValidation::c1, funct::cos(), AlCaHLTBitMon_ParallelJobs::p, p2, phi, TwoBodyDecayParameters::phi, TwoBodyDecayParameters::px, TwoBodyDecayParameters::py, TwoBodyDecayParameters::pz, rotationMatrix(), funct::sin(), mathSSE::sqrt(), thePrimaryMass, theSecondaryMass, TwoBodyDecayParameters::theta, and theta().

Referenced by cartesianSecondaryMomenta(), TwoBodyDecayTrajectoryState::construct(), and TwoBodyDecayEstimator::constructMatrices().

{
  double px = param[TwoBodyDecayParameters::px];
  double py = param[TwoBodyDecayParameters::py];
  double pz = param[TwoBodyDecayParameters::pz];
  double theta = param[TwoBodyDecayParameters::theta];
  double phi = param[TwoBodyDecayParameters::phi];

  // compute transverse and absolute momentum
  double pT2 = px*px + py*py;
  double p2 = pT2 + pz*pz;
  double p = sqrt( p2 );

  double sphi = sin( phi );
  double cphi = cos( phi );
  double stheta = sin( theta );
  double ctheta = cos( theta );

  // some constants from kinematics
  double c1 = 0.5*thePrimaryMass/theSecondaryMass;
  double c2 = sqrt( c1*c1 - 1. );
  double c3 = 0.5*c2*ctheta/c1;
  double c4 = sqrt( p2 + thePrimaryMass*thePrimaryMass );

  // momentum of decay particle 1 in the primary's boosted frame
  AlgebraicMatrix pplus( 3, 1 );
  pplus[0][0] = theSecondaryMass*c2*stheta*cphi;
  pplus[1][0] = theSecondaryMass*c2*stheta*sphi;
  pplus[2][0] = 0.5*p + c3*c4;

  // momentum of decay particle 2 in the primary's boosted frame
  AlgebraicMatrix pminus( 3, 1 );
  pminus[0][0] = -pplus[0][0];
  pminus[1][0] = -pplus[1][0];
  pminus[2][0] = 0.5*p - c3*c4;

  AlgebraicMatrix rotMat = rotationMatrix( px, py, pz );

  return std::make_pair( rotMat*pplus, rotMat*pminus );
}

const std::pair< AlgebraicVector, AlgebraicVector > TwoBodyDecayModel::cartesianSecondaryMomenta

(

const TwoBodyDecay &

tbd

)

Momenta of the secondaries in cartesian repraesentation.

Definition at line 130 of file TwoBodyDecayModel.cc.

References cartesianSecondaryMomenta(), and TwoBodyDecay::parameters().

{
  return cartesianSecondaryMomenta( tbd.parameters() );
}

const std::pair< AlgebraicVector, AlgebraicVector > TwoBodyDecayModel::cartesianSecondaryMomenta

(

const TwoBodyDecayParameters &

tbdparam

)

Momenta of the secondaries in cartesian repraesentation.

Definition at line 135 of file TwoBodyDecayModel.cc.

References cartesianSecondaryMomenta(), and TwoBodyDecayParameters::parameters().

{
  return cartesianSecondaryMomenta( tbdparam.parameters() );
}

AlgebraicVector TwoBodyDecayModel::convertCurvilinearToCartesian	(	AlgebraicVector	curv,
		double	zMagField
	)

Convert vector from curvilinear to cartesian coordinates (needs the z-component of magnetic field in inverse GeV as input).

Definition at line 75 of file TwoBodyDecayModel.cc.

References funct::cos(), funct::sin(), and funct::tan().

{
  double rt = fabs( zMagField/curv[0] );

  AlgebraicVector cart( 3 );
  cart[0] = rt*cos( curv[2] );
  cart[1] = rt*sin( curv[2] );
  cart[2] = rt/tan( curv[1] );

  return cart;
}

AlgebraicMatrix TwoBodyDecayModel::curvilinearToCartesianJacobian	(	double	rho,
		double	theta,
		double	phi,
		double	zMagField
	)

Jacobian for transformation from curvilinear to cartesian representation (needs the z-component of magnetic field in inverse GeV as input).

Definition at line 39 of file TwoBodyDecayModel.cc.

References conv, funct::cos(), lumiQueryAPI::q, and funct::sin().

Referenced by curvilinearToCartesianJacobian().

{
  double q = ( ( rho < 0 ) ? -1. : 1. );
  double conv = q*zMagField;

  double stheta = sin( theta );
  double ctheta = cos( theta );
  double sphi = sin( phi );
  double cphi = cos( phi );

  AlgebraicMatrix curv2cart( 3, 3 );

  curv2cart[0][0] = -rho*cphi;
  curv2cart[0][1] = -rho*sphi;
  curv2cart[0][2] = 0.;

  curv2cart[1][0] = cphi*stheta*ctheta;
  curv2cart[1][1] = sphi*stheta*ctheta;
  curv2cart[1][2] = -stheta*stheta;

  curv2cart[2][0] = -sphi;
  curv2cart[2][1] = cphi;
  curv2cart[2][2] = 0.;

  curv2cart *= rho/conv;

  return curv2cart;
}

AlgebraicMatrix TwoBodyDecayModel::curvilinearToCartesianJacobian	(	AlgebraicVector	curv,
		double	zMagField
	)

Jacobian for transformation from curvilinear to cartesian representation (needs the z-component of magnetic field in inverse GeV as input).

Definition at line 69 of file TwoBodyDecayModel.cc.

References curvilinearToCartesianJacobian().

{
  return this->curvilinearToCartesianJacobian( curv[0], curv[1], curv[2], zMagField );
}

AlgebraicMatrix TwoBodyDecayModel::rotationMatrix	(	double	px,
		double	py,
		double	pz
	)

Rotates a vector pointing in z-direction into the direction defined by p=(px,py,pz).

Definition at line 12 of file TwoBodyDecayModel.cc.

References AlCaHLTBitMon_ParallelJobs::p, p2, and mathSSE::sqrt().

Referenced by cartesianSecondaryMomenta(), TwoBodyDecayDerivatives::dqsdm(), TwoBodyDecayDerivatives::dqsdphi(), TwoBodyDecayDerivatives::dqsdtheta(), and TwoBodyDecayLinearizationPointFinder::getLinearizationPoint().

{
  // compute transverse and absolute momentum
  double pT2 = px*px + py*py;
  double p2 = pT2 + pz*pz;
  double pT = sqrt( pT2 );
  double p = sqrt( p2 );

  AlgebraicMatrix rotMat( 3, 3 );

  // compute rotation matrix
  rotMat[0][0] = px*pz/pT/p;
  rotMat[0][1] = -py/pT;
  rotMat[0][2] = px/p;

  rotMat[1][0] = py*pz/pT/p;
  rotMat[1][1] = px/pT;
  rotMat[1][2] = py/p;

  rotMat[2][0] = -pT/p;
  rotMat[2][1] = 0.;
  rotMat[2][2] = pz/p;

  return rotMat;
}

Member Data Documentation

double TwoBodyDecayModel::thePrimaryMass

private

Definition at line 56 of file TwoBodyDecayModel.h.

Referenced by cartesianSecondaryMomenta().

double TwoBodyDecayModel::theSecondaryMass

private

Definition at line 57 of file TwoBodyDecayModel.h.

Referenced by cartesianSecondaryMomenta().