JetSubStructureUtils::Qjets Class Reference

#include <Qjets.h>

Collaboration diagram for JetSubStructureUtils::Qjets:

Public Member Functions
	Qjets (double zcut, double dcut_fctr, double exp_min, double exp_max, double rigidity, double truncation_fctr)
void	Cluster (fastjet::ClusterSequence &cs)
void	SetRandSeed (unsigned int seed)

Private Member Functions
double	d_ij (const fastjet::PseudoJet &v1, const fastjet::PseudoJet &v2) const
void	ComputeDCut (fastjet::ClusterSequence &cs)
double	Rand ()
bool	Prune (jet_distance &jd, fastjet::ClusterSequence &cs)
bool	JetsUnmerged (const jet_distance &jd) const
bool	JetUnmerged (int num) const
void	ComputeNewDistanceMeasures (fastjet::ClusterSequence &cs, int new_jet)
void	ComputeAllDistances (const std::vector< fastjet::PseudoJet > &inp)
double	ComputeMinimumDistance ()
double	ComputeNormalization (double dmin)
jet_distance	GetNextDistance ()
bool	Same (const jet_distance &lhs, const jet_distance &rhs)

Private Attributes
TRandom3	m_rand
double	m_zcut
double	m_dcut
double	m_dcut_fctr
double	m_exp_min
double	m_exp_max
double	m_rigidity
double	m_truncation_fctr
std::map< int, bool >	m_merged_jets
std::priority_queue< jet_distance, std::vector< jet_distance >, JetDistanceCompare >	m_distances

Detailed Description

Definition at line 31 of file Qjets.h.

Constructor & Destructor Documentation

Qjets()

Qjets::Qjets	(	double	zcut,
		double	dcut_fctr,
		double	exp_min,
		double	exp_max,
		double	rigidity,
		double	truncation_fctr )

Definition at line 10 of file Qjets.cxx.

: m_rand(),
  m_zcut(zcut), 
  m_dcut(-1.), 
  m_dcut_fctr(dcut_fctr),
  m_exp_min(exp_min),
  m_exp_max(exp_max),
  m_rigidity(rigidity),
  m_truncation_fctr(truncation_fctr)
{
}

Member Function Documentation

Cluster()

void Qjets::Cluster

(

fastjet::ClusterSequence &

cs

)

Definition at line 80 of file Qjets.cxx.

                                              {
  ComputeDCut(cs);
 
  // Populate all the distances
  ComputeAllDistances(cs.jets());
  jet_distance jd = GetNextDistance();
 
  while(!m_distances.empty() && jd.dij != -1.){
    if(!Prune(jd,cs)){
      //      m_merged_jets.push_back(jd.j1);
      //      m_merged_jets.push_back(jd.j2);
      m_merged_jets[jd.j1] = true;
      m_merged_jets[jd.j2] = true;
 
      int new_jet;
      cs.plugin_record_ij_recombination(jd.j1, jd.j2, 1., new_jet);
      assert(JetUnmerged(new_jet));
      ComputeNewDistanceMeasures(cs,new_jet);
    } else {
      double j1pt = cs.jets()[jd.j1].perp();
      double j2pt = cs.jets()[jd.j2].perp();
      if(j1pt>j2pt){
        //  m_merged_jets.push_back(jd.j2);
        m_merged_jets[jd.j2] = true;
        cs.plugin_record_iB_recombination(jd.j2, 1.);
      } else {
        //  m_merged_jets.push_back(jd.j1);
        m_merged_jets[jd.j1] = true;
        cs.plugin_record_iB_recombination(jd.j1, 1.);
      }
    }
    jd = GetNextDistance();
  } 
 
  // merge remaining jets with beam
  [[maybe_unused]] int num_merged_final(0);
 
  for(unsigned int i = 0 ; i < cs.jets().size(); i++)
    if(JetUnmerged(i)){
      num_merged_final++;
      cs.plugin_record_iB_recombination(i,1.);
    }
 
  assert(num_merged_final < 2);
}

ComputeAllDistances()

void Qjets::ComputeAllDistances ( const std::vector< fastjet::PseudoJet > & inp )

private

Definition at line 144 of file Qjets.cxx.

                                                                  {
  for(unsigned int i = 0 ; i < inp.size()-1; i++){
    // jet-jet distances
    for(unsigned int j = i+1 ; j < inp.size(); j++){
      jet_distance jd{};
      jd.j1 = i;
      jd.j2 = j;
      if(jd.j1 != jd.j2){
        jd.dij = d_ij(inp[i],inp[j]);
        m_distances.push(jd);
      }
    }    
  }
}

ComputeDCut()

void Qjets::ComputeDCut ( fastjet::ClusterSequence & cs )

private

Definition at line 126 of file Qjets.cxx.

                                                  {
  // assume all jets in cs form a single jet.  compute mass and pt
  fastjet::PseudoJet sum(0.,0.,0.,0.);
  for(vector<fastjet::PseudoJet>::const_iterator it = cs.jets().begin(); it != cs.jets().end(); ++it)
    sum += (*it);
  m_dcut = 2. * m_dcut_fctr * sum.m()/sum.perp(); 
}

ComputeMinimumDistance()

double JetSubStructureUtils::Qjets::ComputeMinimumDistance ( )

private

ComputeNewDistanceMeasures()

void Qjets::ComputeNewDistanceMeasures ( fastjet::ClusterSequence & cs, int new_jet )

private

Definition at line 159 of file Qjets.cxx.

                                                                              {
  // jet-jet distances
  for(unsigned int i = 0; i < cs.jets().size(); i++)
    if(JetUnmerged(i) && ((int)i) != new_jet){
      jet_distance jd{};
      jd.j1 = new_jet;
      jd.j2 = i;
      jd.dij = d_ij(cs.jets()[jd.j1], cs.jets()[jd.j2]);
      m_distances.push(jd);
    }
}

ComputeNormalization()

double JetSubStructureUtils::Qjets::ComputeNormalization ( double dmin )

private

d_ij()

double Qjets::d_ij ( const fastjet::PseudoJet & v1, const fastjet::PseudoJet & v2 ) const

private

Definition at line 171 of file Qjets.cxx.

                                                                              {
  double p1 = v1.perp();
  double p2 = v2.perp();
  double ret = pow(min(p1,p2),m_exp_min) * pow(max(p1,p2),m_exp_max) * v1.squared_distance(v2);
  assert(!std::isnan(ret));
  return ret; 
}

GetNextDistance()

jet_distance Qjets::GetNextDistance ( )

private

Definition at line 34 of file Qjets.cxx.

                                   {
  vector< pair<jet_distance, double> > popped_distances;
  double norm(0.);
  jet_distance ret{};
  ret.j1 = -1;
  ret.j2 = -1;
  ret.dij = -1.;
  bool dmin_set(false);
  double dmin(0.);
 
  while(!m_distances.empty()){
    jet_distance dist = m_distances.top();
    m_distances.pop();
    if(JetsUnmerged(dist)){
      if(!dmin_set){
        dmin = dist.dij;
        dmin_set = true;
      }
      double weight = exp(-m_rigidity * (dist.dij-dmin) /dmin);
      popped_distances.emplace_back(dist,weight);        
      norm += weight; 
      if(weight/norm < m_truncation_fctr)
        break;            
    }
  }
 
  double rand(Rand()), tot_weight(0.);
  if (!popped_distances.empty()) {
    const double inv_norm = norm == 0 ? 1 : 1. / norm;
    for(vector<pair<jet_distance, double> >::iterator it = popped_distances.begin(); it != popped_distances.end(); ++it){
      tot_weight += (*it).second * inv_norm;
      if(tot_weight >= rand){
        ret = (*it).first;
        break;
      }
    }
  }
 
  // repopulate in reverse (maybe quicker?)
  for(vector<pair<jet_distance, double> >::reverse_iterator it = popped_distances.rbegin(); it != popped_distances.rend(); ++it)
    if(JetsUnmerged((*it).first))
      m_distances.push((*it).first);
 
  return ret;
}

JetsUnmerged()

bool Qjets::JetsUnmerged ( const jet_distance & jd ) const

private

Definition at line 30 of file Qjets.cxx.

                                                    {
  return JetUnmerged(jd.j1) && JetUnmerged(jd.j2);
}

JetUnmerged()

bool Qjets::JetUnmerged ( int num ) const

private

Definition at line 26 of file Qjets.cxx.

                                    {
  return m_merged_jets.find(num) == m_merged_jets.end();
}

Prune()

bool Qjets::Prune ( jet_distance & jd, fastjet::ClusterSequence & cs )

private

Definition at line 134 of file Qjets.cxx.

                                                             {
  double pt1 = cs.jets()[jd.j1].perp();
  double pt2 = cs.jets()[jd.j2].perp();
  fastjet::PseudoJet sum_jet = cs.jets()[jd.j1]+cs.jets()[jd.j2];
  double sum_pt = sum_jet.perp();
  double z = min(pt1,pt2)/sum_pt;
  double d = sqrt(cs.jets()[jd.j1].plain_distance(cs.jets()[jd.j2]));
  return (d > m_dcut) && (z < m_zcut);
}

Rand()

double Qjets::Rand ( )

private

Definition at line 179 of file Qjets.cxx.

                  {
  return m_rand.Rndm();
}

Same()

bool JetSubStructureUtils::Qjets::Same ( const jet_distance & lhs, const jet_distance & rhs )

private

SetRandSeed()

void Qjets::SetRandSeed

(

unsigned int

seed

)

Definition at line 22 of file Qjets.cxx.

                                        {
  m_rand.SetSeed(seed);
}

Member Data Documentation

m_dcut

double JetSubStructureUtils::Qjets::m_dcut

private

Definition at line 34 of file Qjets.h.

m_dcut_fctr

double JetSubStructureUtils::Qjets::m_dcut_fctr

private

Definition at line 34 of file Qjets.h.

m_distances

std::priority_queue<jet_distance, std::vector<jet_distance>, JetDistanceCompare> JetSubStructureUtils::Qjets::m_distances

private

Definition at line 36 of file Qjets.h.

m_exp_max

double JetSubStructureUtils::Qjets::m_exp_max

private

Definition at line 34 of file Qjets.h.

m_exp_min

double JetSubStructureUtils::Qjets::m_exp_min

private

Definition at line 34 of file Qjets.h.

m_merged_jets

std::map<int,bool> JetSubStructureUtils::Qjets::m_merged_jets

private

Definition at line 35 of file Qjets.h.

m_rand

TRandom3 JetSubStructureUtils::Qjets::m_rand

private

Definition at line 33 of file Qjets.h.

m_rigidity

double JetSubStructureUtils::Qjets::m_rigidity

private

Definition at line 34 of file Qjets.h.

m_truncation_fctr

double JetSubStructureUtils::Qjets::m_truncation_fctr

private

Definition at line 34 of file Qjets.h.

m_zcut

double JetSubStructureUtils::Qjets::m_zcut

private

Definition at line 34 of file Qjets.h.

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

• Qjets.h
• Qjets.cxx