MultiTrackMassKinematicConstraint Class Reference

#include <MultiTrackMassKinematicConstraint.h>

Inheritance diagram for MultiTrackMassKinematicConstraint:

List of all members.

Public Member Functions
virtual MultiTrackMassKinematicConstraint *	clone () const
	MultiTrackMassKinematicConstraint (const ParticleMass &theMass, const unsigned int nbrParticles)
virtual int	numberOfEquations () const
virtual AlgebraicMatrix	parametersDerivative (const std::vector< KinematicState > states, const GlobalPoint &point) const
virtual AlgebraicMatrix	positionDerivative (const std::vector< KinematicState > states, const GlobalPoint &point) const
virtual AlgebraicVector	value (const std::vector< KinematicState > states, const GlobalPoint &point) const
Private Attributes
const ParticleMass	mass
const unsigned int	nPart

---

Detailed Description

Constraint to force some of the particles in the fit to have a certain invariant mass.

Definition at line 13 of file MultiTrackMassKinematicConstraint.h.

---

Constructor & Destructor Documentation

MultiTrackMassKinematicConstraint::MultiTrackMassKinematicConstraint	(	const ParticleMass &	theMass,
		const unsigned int	nbrParticles
	)		[inline]

Constructor

Parameters:

theMass	the mass to constrain the states
nbrParticles	the number of particles to use (in case more than that number are present in the fit, the first will be used)

Definition at line 22 of file MultiTrackMassKinematicConstraint.h.

Referenced by clone().

        : mass(theMass), nPart(nbrParticles)
  {}

---

Member Function Documentation

virtual MultiTrackMassKinematicConstraint* MultiTrackMassKinematicConstraint::clone

(

void

)

const [inline, virtual]

Implements MultiTrackKinematicConstraint.

Definition at line 57 of file MultiTrackMassKinematicConstraint.h.

References MultiTrackMassKinematicConstraint().

  {return new MultiTrackMassKinematicConstraint(*this);}

virtual int MultiTrackMassKinematicConstraint::numberOfEquations

(

)

const [inline, virtual]

Number of equations per track used for the fit

Implements MultiTrackKinematicConstraint.

Definition at line 55 of file MultiTrackMassKinematicConstraint.h.

{return 1;}

AlgebraicMatrix MultiTrackMassKinematicConstraint::parametersDerivative	(	const std::vector< KinematicState >	states,
		const GlobalPoint &	point
	)		const [virtual]

Returns a matrix of derivatives of constraint equations w.r.t. particle parameters

Implements MultiTrackKinematicConstraint.

Definition at line 29 of file MultiTrackMassKinematicConstraint.cc.

References a, i, nPart, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

{
  if(states.size()<nPart) throw VertexException("MultiTrackMassKinematicConstraint::not enough states given");

  AlgebraicMatrix res(1,states.size()*7,0);

  double sumEnergy = 0, sumPx=0, sumPy=0., sumPz=0.;

 double a;
  for (unsigned int i=0;i<nPart;++i) {
    a = -states[i].particleCharge() * states[i].magneticField()->inInverseGeV(states[i].globalPosition()).z();

    sumEnergy += states[i].kinematicParameters().energy();
    sumPx += states[i].kinematicParameters()(3) - a*(point.y() - states[i].kinematicParameters()(1));
    sumPy += states[i].kinematicParameters()(4) + a*(point.x() - states[i].kinematicParameters()(0));
    sumPz += states[i].kinematicParameters()(5);
  }

  for (unsigned int i=0;i<nPart;++i) {
    a = -states[i].particleCharge() * states[i].magneticField()->inInverseGeV(states[i].globalPosition()).z();

 //x derivatives:
    res(1,1+i*7) = 2*a*sumPy;

 //y derivatives:
    res(1,2+i*7) = -2*a*sumPx;

 //z components:
    res(1,3+i*7)  = 0.;

 //px components:
    res(1,4+i*7)  = 2*sumEnergy/states[i].kinematicParameters().energy()*states[i].kinematicParameters()(3) - 2*sumPx;

 //py components:
    res(1,5+i*7)  = 2*sumEnergy/states[i].kinematicParameters().energy()*states[i].kinematicParameters()(4) - 2*sumPy;

 //pz1 components:
    res(1,6+i*7)  = 2*sumEnergy/states[i].kinematicParameters().energy()*states[i].kinematicParameters()(5) - 2*sumPz;

 //mass components:
    res(1,7+i*7)  = 2*states[i].kinematicParameters().mass()*sumEnergy/states[i].kinematicParameters().energy();
  }
  return res;
}

AlgebraicMatrix MultiTrackMassKinematicConstraint::positionDerivative	(	const std::vector< KinematicState >	states,
		const GlobalPoint &	point
	)		const [virtual]

Returns a matrix of derivatives of constraint equations w.r.t. vertex position

Implements MultiTrackKinematicConstraint.

Definition at line 75 of file MultiTrackMassKinematicConstraint.cc.

References a, i, nPart, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

{
  AlgebraicMatrix res(1,3,0);
  if(states.size()<nPart) throw VertexException("MultiTrackMassKinematicConstraint::not enough states given");

  double sumA = 0, sumPx=0, sumPy=0.;

  double a;
  for (unsigned int i=0;i<nPart;++i) {
    a = -states[i].particleCharge() * states[i].magneticField()->inInverseGeV(states[i].globalPosition()).z();
    sumA += a;

    sumPx += states[i].kinematicParameters()(3) - a*(point.y() - states[i].kinematicParameters()(1));
    sumPy += states[i].kinematicParameters()(4) + a*(point.x() - states[i].kinematicParameters()(0));
  }

 //xv component
  res(1,1) = - 2 * sumPy * sumA;

 //yv component
  res(1,2) =   2 * sumPx * sumA;

 //zv component
  res(1,3) = 0.;

  return res;
}

AlgebraicVector MultiTrackMassKinematicConstraint::value	(	const std::vector< KinematicState >	states,
		const GlobalPoint &	point
	)		const [virtual]

Returns a vector of values of constraint equations at the point where the input particles are defined.

Implements MultiTrackKinematicConstraint.

Definition at line 5 of file MultiTrackMassKinematicConstraint.cc.

References a, i, mass, nPart, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

{
 if(states.size()<nPart) throw VertexException("MultiTrackMassKinematicConstraint::not enough states given");

 double sumEnergy = 0, sumPx=0, sumPy=0., sumPz=0.;

 double a;
 for (unsigned int i=0;i<nPart;++i) {
    a = -states[i].particleCharge() * states[i].magneticField()->inInverseGeV(states[i].globalPosition()).z();

    sumEnergy += states[i].kinematicParameters().energy();
    sumPx += states[i].kinematicParameters()(3) - a*(point.y() - states[i].kinematicParameters()(1));
    sumPy += states[i].kinematicParameters()(4) + a*(point.x() - states[i].kinematicParameters()(0));
    sumPz += states[i].kinematicParameters()(5);
 }

 double j_m = sumPx*sumPx + sumPy*sumPy + sumPz*sumPz;

 AlgebraicVector res(1,0);
 res(1)  = sumEnergy*sumEnergy - j_m - mass*mass;
 return res;
}

---

Member Data Documentation

const ParticleMass MultiTrackMassKinematicConstraint::mass [private]

Definition at line 62 of file MultiTrackMassKinematicConstraint.h.

Referenced by value().

const unsigned int MultiTrackMassKinematicConstraint::nPart [private]

Definition at line 63 of file MultiTrackMassKinematicConstraint.h.

Referenced by parametersDerivative(), positionDerivative(), and value().