CP::PartonHistoryUtils Namespace Reference

Functions
const xAOD::TruthParticle &	findAfterFSR (const xAOD::TruthParticle &particle)
	Return particle after FSR (before the decay vertex).
bool	isChildOf (const xAOD::TruthParticle &parent, const xAOD::TruthParticle &potentialChild)
bool	isBrokenTop (const xAOD::TruthParticle &particle)
	Looking for tops without children -> must be broken.
bool	isAfterFSR (const xAOD::TruthParticle &particle)
	Determine whether particle is afterFSR.
bool	hasParticleIdenticalParent (const xAOD::TruthParticle &particle)
	Return true when any parent of the particle has the same pdgId as the particle.
bool	hasParentPdgId (const xAOD::TruthParticle &particle, int PdgId)
bool	hasParentPdgId (const xAOD::TruthParticle &particle)
bool	hasParentAbsPdgId (const xAOD::TruthParticle &particle, int absPdgId)
bool	hasIdenticalChild (const xAOD::TruthParticle &particle)
bool	isQuarkFromPDF (const xAOD::TruthParticle &particle)

Function Documentation

findAfterFSR()

const xAOD::TruthParticle & CP::PartonHistoryUtils::findAfterFSR

(

const xAOD::TruthParticle &

particle

)

Return particle after FSR (before the decay vertex).

Definition at line 102 of file PartonHistoryUtils.cxx.

                                                                  {
  // Follow the chain of identical children down to the last copy.
  const xAOD::TruthParticle* current = &p;
  while (const xAOD::TruthParticle* child = findIdenticalChild(*current))
    current = child;
  return *current;
}

hasIdenticalChild()

bool CP::PartonHistoryUtils::hasIdenticalChild

(

const xAOD::TruthParticle &

particle

)

Definition at line 47 of file PartonHistoryUtils.cxx.

                                                   {
  // Checks if the given particle has at least one child with an identical PDG
  // ID.
  return findIdenticalChild(p) != nullptr;
}

hasParentAbsPdgId()

bool CP::PartonHistoryUtils::hasParentAbsPdgId	(	const xAOD::TruthParticle &	particle,
		int	absPdgId )

Definition at line 53 of file PartonHistoryUtils.cxx.

                                                                 {
  // No parent recorded, or a broken truth link to it, is treated as "no
  // parent".
  if (p.nParents() == 0)
    return false;
  const xAOD::TruthParticle* parent = p.parent(0);
  // Checks if the parent of the given particle has a specific absolute PDG ID.
  return parent && parent->absPdgId() == absPdgId;
}

hasParentPdgId() [1/2]

bool CP::PartonHistoryUtils::hasParentPdgId

(

const xAOD::TruthParticle &

particle

)

Definition at line 42 of file PartonHistoryUtils.cxx.

                                                {
  // Checks if the parent of the given particle has a specific PDG ID.
  return hasParentPdgId(p, p.pdgId());
}

hasParentPdgId() [2/2]

bool CP::PartonHistoryUtils::hasParentPdgId	(	const xAOD::TruthParticle &	particle,
		int	PdgId )

Definition at line 32 of file PartonHistoryUtils.cxx.

                                                           {
  // No parent recorded, or a broken truth link to it, is treated as "no
  // parent".
  if (p.nParents() == 0)
    return false;
  const xAOD::TruthParticle* parent = p.parent(0);
  // Checks if the parent of the given particle has a specific PDG ID.
  return parent && parent->pdgId() == pdgId;
}

hasParticleIdenticalParent()

bool CP::PartonHistoryUtils::hasParticleIdenticalParent

(

const xAOD::TruthParticle &

particle

)

Return true when any parent of the particle has the same pdgId as the particle.

A broken parent truth link within nParents() is treated as "not identical".

Definition at line 63 of file PartonHistoryUtils.cxx.

                                                            {
  // Checks if particle and any of its parents are identical. A broken
  // parent truth link is treated as "not identical".
  for (size_t i = 0; i < p.nParents(); i++) {
    const xAOD::TruthParticle* parent = p.parent(i);
    if (parent && parent->pdgId() == p.pdgId())
      return true;
  }  // for
  return false;
}

isAfterFSR()

bool CP::PartonHistoryUtils::isAfterFSR

(

const xAOD::TruthParticle &

particle

)

Determine whether particle is afterFSR.

Definition at line 98 of file PartonHistoryUtils.cxx.

                                            {
  return !hasIdenticalChild(p);
}

isBrokenTop()

bool CP::PartonHistoryUtils::isBrokenTop

(

const xAOD::TruthParticle &

particle

)

Looking for tops without children -> must be broken.

Definition at line 114 of file PartonHistoryUtils.cxx.

                                             {
  // check if particle is a top without children.
  return (p.absPdgId() == 6 && p.nChildren() == 0);
}

isChildOf()

bool CP::PartonHistoryUtils::isChildOf	(	const xAOD::TruthParticle &	parent,
		const xAOD::TruthParticle &	potentialChild )

Definition at line 74 of file PartonHistoryUtils.cxx.

                                               {
  // Checks if child is child of parent.
  if (parent.uid() == child.uid()) {
    return true;
  }
  // Loop through all children of the parent
  for (size_t i = 0; i < parent.nChildren(); ++i) {
    const xAOD::TruthParticle* c = parent.child(i);
    // A broken child truth link is treated as "not this child" and skipped.
    // Recursively check if child is a child of the current child
    if (c && isChildOf(*c, child)) {
      return true;
    }
  }
  // If child is not found in the children or their descendants, return
  // false
  return false;
}

isQuarkFromPDF()

bool CP::PartonHistoryUtils::isQuarkFromPDF

(

const xAOD::TruthParticle &

particle

)

Definition at line 119 of file PartonHistoryUtils.cxx.

                                                       {
  // In principle we could use some status codes here, e.g. 31/41/42/53/61 for
  // Pythia 8. But that is not guaranteed to be compatible across generators,
  // so instead we just check if it's a massless quark.
  bool isQuark = 1 <= particle.absPdgId() && particle.absPdgId() <= 5;
  bool isMassless = particle.m() == 0;
  return isQuark && isMassless;
}