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 (const AlgebraicVector &curv, double zMagField)
AlgebraicMatrix	curvilinearToCartesianJacobian (double rho, double theta, double phi, double zMagField)
AlgebraicMatrix	curvilinearToCartesianJacobian (const 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, BPhysicsValidation_cfi::pminus, BPhysicsValidation_cfi::pplus, 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	(	const 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	(	const 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, PVValHelper::pT, 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().