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 15 of file TwoBodyDecayModel.h.

Constructor & Destructor Documentation

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

Definition at line 4 of file TwoBodyDecayModel.cc.

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

TwoBodyDecayModel::~TwoBodyDecayModel

(

)

Definition at line 7 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 80 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(), TwoBodyDecayEstimator::constructMatrices(), and TwoBodyDecayMomConstraintProducer::momentaAtVertex().

                                  {
  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 121 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 125 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 69 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 34 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 65 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 9 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 53 of file TwoBodyDecayModel.h.

Referenced by cartesianSecondaryMomenta().

double TwoBodyDecayModel::theSecondaryMass

private

Definition at line 54 of file TwoBodyDecayModel.h.

Referenced by cartesianSecondaryMomenta().