RestFrame Class Reference

Rest frame of a particle. More...

#include <ReferenceFrame.h>

Inheritance diagram for RestFrame:

Public Member Functions
	RestFrame (const Particle *particle)
	Create new rest frame.
virtual ROOT::Math::XYZVector	getVertex (const ROOT::Math::XYZVector &vector) const override
	Get vertex 3-vector in rest frame system.
virtual ROOT::Math::PxPyPzEVector	getMomentum (const ROOT::Math::PxPyPzEVector &vector) const override
	Get Lorentz vector in rest frame System.
virtual TMatrixFSym	getMomentumErrorMatrix (const TMatrixFSym &matrix) const override
	Get Momentum error matrix in rest frame.
virtual TMatrixFSym	getVertexErrorMatrix (const TMatrixFSym &matrix) const override
	Get Vertex error matrix in rest frame.
virtual ROOT::Math::XYZVector	getVertex (const Particle *particle) const
	Wrapper for particles.
virtual ROOT::Math::PxPyPzEVector	getMomentum (const Particle *particle) const
	Wrapper for particles.
virtual TMatrixFSym	getMomentumErrorMatrix (const Particle *particle) const
	Wrapper for particles.
virtual TMatrixFSym	getVertexErrorMatrix (const Particle *particle) const
	Wrapper for particles.

Static Public Member Functions
static const ReferenceFrame &	GetCurrent ()
	Get current rest frame.

Static Private Member Functions
static void	Push (const ReferenceFrame *frame)
	Push rest frame of given particle.
static void	Pop ()
	Pop current rest frame.

Private Attributes
ROOT::Math::PxPyPzEVector	m_momentum
	momentum of RF in the lab frame
ROOT::Math::XYZVector	m_displacement
	displacement of RF origin in th lab frame
ROOT::Math::XYZVector	m_boost
	boost of RF relative to the lab frame
ROOT::Math::Boost	m_lab2restframe
	Lorentz transformation connecting lab and rest frame.

Static Private Attributes
static std::stack< const ReferenceFrame * >	m_reference_frames
	Stack of current rest frames.

Detailed Description

Rest frame of a particle.

Definition at line 132 of file ReferenceFrame.h.

Constructor & Destructor Documentation

RestFrame()

RestFrame ( const Particle *  particle )

explicit

Create new rest frame.

Definition at line 18 of file ReferenceFrame.cc.

                                             :
  m_momentum(particle->get4Vector()),
  m_displacement(particle->getVertex()),
  m_boost(-m_momentum.BoostToCM()),
  m_lab2restframe(-m_boost)
{
}

Member Function Documentation

GetCurrent()

const ReferenceFrame & GetCurrent ( )

staticinherited

Get current rest frame.

Returns

RestFrame

Definition at line 26 of file ReferenceFrame.cc.

{
  if (m_reference_frames.empty()) {
    static LabFrame _default;
    return _default;
  } else {
    return *m_reference_frames.top();
  }
}

getMomentum() [1/2]

virtual ROOT::Math::PxPyPzEVector getMomentum ( const Particle *  particle ) const

inlinevirtualinherited

Wrapper for particles.

Parameters

particle

particle

Returns

momentum 4-vector in reference frame

Definition at line 60 of file ReferenceFrame.h.

    {
      return getMomentum(particle->get4Vector());
    }

getMomentum() [2/2]

ROOT::Math::PxPyPzEVector getMomentum ( const ROOT::Math::PxPyPzEVector &  vector ) const

overridevirtual

Get Lorentz vector in rest frame System.

Parameters

vector

Lorentz vector from particle

Returns

Lorentz vector in rest frame System

Implements ReferenceFrame.

Definition at line 48 of file ReferenceFrame.cc.

{
  // 1. Boost momentum into rest frame
  return m_lab2restframe * vector;
}

getMomentumErrorMatrix() [1/2]

virtual TMatrixFSym getMomentumErrorMatrix ( const Particle *  particle ) const

inlinevirtualinherited

Wrapper for particles.

Parameters

particle

particle

Returns

Covariance matrix in reference frame

Definition at line 77 of file ReferenceFrame.h.

    {
      return getMomentumErrorMatrix(particle->getMomentumErrorMatrix());
    }

getMomentumErrorMatrix() [2/2]

TMatrixFSym getMomentumErrorMatrix ( const TMatrixFSym &  matrix ) const

overridevirtual

Get Momentum error matrix in rest frame.

Parameters

matrix

Covariance matrix from particle

Returns

Covariance matrix in rest frame

Implements ReferenceFrame.

Definition at line 54 of file ReferenceFrame.cc.

{
  double lorentzrotationvalues[16];
  m_lab2restframe.GetLorentzRotation(lorentzrotationvalues);
  TMatrixD lorentzrot(4, 4, lorentzrotationvalues);
 
  TMatrixFSym tmp_matrix(matrix);
 
  return tmp_matrix.Similarity(lorentzrot);
}

getVertex() [1/2]

virtual ROOT::Math::XYZVector getVertex ( const Particle *  particle ) const

inlinevirtualinherited

Wrapper for particles.

Parameters

particle

Returns

3-vector in reference frame

Definition at line 43 of file ReferenceFrame.h.

    {
      return getVertex(particle->getVertex());
    }

getVertex() [2/2]

ROOT::Math::XYZVector getVertex ( const ROOT::Math::XYZVector &  vector ) const

overridevirtual

Get vertex 3-vector in rest frame system.

Parameters

vector

3-vector from particle

Returns

3-vector in rest frame System

Implements ReferenceFrame.

Definition at line 36 of file ReferenceFrame.cc.

{
  // Transform Vertex from lab into rest frame:
  // 1. Subtract displacement of rest frame origin in the lab frame
  // 2. Use Lorentz Transformation to Boost Vertex vector into rest frame
  // 3. Subtract movement of vertex end due to the time difference between
  //    the former simultaneous measured vertex points (see derivation of Lorentz contraction)
  ROOT::Math::XYZVector v(vector - m_displacement);
  ROOT::Math::PxPyPzEVector a = m_lab2restframe * ROOT::Math::PxPyPzEVector(v.X(), v.Y(), v.Z(), 0);
  return a.Vect() - m_boost * a.T();
}

getVertexErrorMatrix() [1/2]

virtual TMatrixFSym getVertexErrorMatrix ( const Particle *  particle ) const

inlinevirtualinherited

Wrapper for particles.

Parameters

particle

Returns

Covariance matrix in reference frame

Definition at line 94 of file ReferenceFrame.h.

    {
      return getVertexErrorMatrix(particle->getVertexErrorMatrix());
    }

getVertexErrorMatrix() [2/2]

TMatrixFSym getVertexErrorMatrix ( const TMatrixFSym &  matrix ) const

overridevirtual

Get Vertex error matrix in rest frame.

Parameters

matrix

Covariance matrix from particle

Returns

Covariance matrix in rest frame

Implements ReferenceFrame.

Definition at line 65 of file ReferenceFrame.cc.

{
  double lorentzrotationvalues[16];
  m_lab2restframe.GetLorentzRotation(lorentzrotationvalues);
  TMatrixD lorentzrot(4, 3);
 
  for (int i = 0; i < 4; ++i)
    for (int j = 0; j < 3; ++j)
      lorentzrot(i, j) = lorentzrotationvalues[4 * i + j];
 
  TMatrixFSym tmp_matrix(matrix);
  auto rotated_error_matrix = tmp_matrix.Similarity(lorentzrot);
 
  TMatrixD timeshift(3, 4);
  timeshift.Zero();
  timeshift(0, 0) = 1;
  timeshift(1, 1) = 1;
  timeshift(2, 2) = 1;
  timeshift(0, 3) = m_boost.X();
  timeshift(1, 3) = m_boost.Y();
  timeshift(2, 3) = m_boost.Z();
 
  return rotated_error_matrix.Similarity(timeshift);
}

Pop()

static void Pop ( )

inlinestaticprivateinherited

Pop current rest frame.

Definition at line 118 of file ReferenceFrame.h.

    {
      m_reference_frames.pop();
    }

Push()

static void Push ( const ReferenceFrame *  frame )

inlinestaticprivateinherited

Push rest frame of given particle.

Parameters

frame

Use this reference frame

Definition at line 110 of file ReferenceFrame.h.

    {
      m_reference_frames.push(frame);
    }

Member Data Documentation

m_boost

ROOT::Math::XYZVector m_boost

private

boost of RF relative to the lab frame

Definition at line 171 of file ReferenceFrame.h.

m_displacement

ROOT::Math::XYZVector m_displacement

private

displacement of RF origin in th lab frame

Definition at line 170 of file ReferenceFrame.h.

m_lab2restframe

ROOT::Math::Boost m_lab2restframe

private

Lorentz transformation connecting lab and rest frame.

Definition at line 172 of file ReferenceFrame.h.

m_momentum

ROOT::Math::PxPyPzEVector m_momentum

private

momentum of RF in the lab frame

Definition at line 169 of file ReferenceFrame.h.

m_reference_frames

std::stack< const ReferenceFrame * > m_reference_frames

staticprivateinherited

Stack of current rest frames.

Definition at line 123 of file ReferenceFrame.h.

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

• analysis/utility/include/ReferenceFrame.h
• analysis/utility/src/ReferenceFrame.cc