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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
namespace Rivet {
/// ATLAS jet substructure measurement
class ATLAS_2012_I1094564 : public Analysis {
public:
ATLAS_2012_I1094564()
: Analysis("ATLAS_2012_I1094564")
{}
// Returns constituents to make it easier to do the filtering
PseudoJets splitjet(fastjet::PseudoJet jet, double& last_R, const FastJets& fj, bool& unclustered) const {
// Build a new cluster sequence just using the constituents of this jet.
fastjet::ClusterSequence cs(fj.clusterSeq()->constituents(jet), fastjet::JetDefinition(fastjet::cambridge_algorithm, M_PI/2.));
// Get the jet back again
vector<fastjet::PseudoJet> remadeJets = cs.inclusive_jets(0.);
if ( remadeJets.size() != 1 ) return remadeJets;
fastjet::PseudoJet remadeJet = remadeJets[0];
fastjet::PseudoJet parent1, parent2;
unclustered = false;
while ( cs.has_parents(remadeJet, parent1, parent2) ) {
if (parent1.squared_distance(parent2) < 0.09) break;
if (parent1.m2() < parent2.m2()) {
fastjet::PseudoJet tmp;
tmp = parent1; parent1 = parent2; parent2 = tmp;
}
double ktdist = parent1.kt_distance(parent2);
double rtycut2 = 0.3*0.3;
if (parent1.m() < 0.67*remadeJet.m() && ktdist > rtycut2*remadeJet.m2()) {
unclustered = true;
break;
} else {
remadeJet = parent1;
}
}
last_R = 0.5 * sqrt(parent1.squared_distance(parent2));
return cs.constituents(remadeJet);
}
fastjet::PseudoJet filterjet(PseudoJets jets, double& stingy_R, const double def_R) const {
if (stingy_R == 0.0) stingy_R = def_R;
stingy_R = def_R < stingy_R ? def_R : stingy_R;
fastjet::JetDefinition stingy_jet_def(fastjet::cambridge_algorithm, stingy_R);
fastjet::ClusterSequence scs(jets, stingy_jet_def);
vector<fastjet::PseudoJet> stingy_jets = sorted_by_pt(scs.inclusive_jets(0));
fastjet::PseudoJet reconst_jet(0, 0, 0, 0);
for (size_t isj = 0; isj < std::min((size_t) 3, stingy_jets.size()); ++isj) {
reconst_jet += stingy_jets[isj];
}
return reconst_jet;
}
// These are custom functions for n-subjettiness.
PseudoJets jetGetAxes(int n_jets, const PseudoJets& inputJets, double subR) const {
// Sanity check
if (inputJets.size() < (size_t) n_jets) {
MSG_ERROR("Not enough input particles.");
return inputJets;
}
// Get subjets, return
fastjet::ClusterSequence sub_clust_seq(inputJets, fastjet::JetDefinition(fastjet::kt_algorithm, subR, fastjet::E_scheme, fastjet::Best));
return sub_clust_seq.exclusive_jets(n_jets);
}
double jetTauValue(double beta, double jet_rad, const PseudoJets& particles, const PseudoJets& axes, double Rcut) const {
double tauNum = 0.0;
double tauDen = 0.0;
if (particles.size() == 0) return 0.0;
for (size_t i = 0; i < particles.size(); i++) {
// find minimum distance (set R large to begin)
double minR = 10000.0;
for (size_t j = 0; j < axes.size(); j++) {
double tempR = sqrt(particles[i].squared_distance(axes[j]));
if (tempR < minR) minR = tempR;
}
if (minR > Rcut) minR = Rcut;
// calculate nominator and denominator
tauNum += particles[i].perp() * pow(minR,beta);
tauDen += particles[i].perp() * pow(jet_rad,beta);
}
// return N-subjettiness (or 0 if denominator is 0)
return safediv(tauNum, tauDen, 0);
}
void jetUpdateAxes(double beta, const PseudoJets& particles, PseudoJets& axes) const {
vector<int> belongsto;
for (size_t i = 0; i < particles.size(); i++) {
// find minimum distance axis
int assign = 0;
double minR = 10000.0;
for (size_t j = 0; j < axes.size(); j++) {
double tempR = sqrt(particles[i].squared_distance(axes[j]));
if (tempR < minR) {
minR = tempR;
assign = j;
}
}
belongsto.push_back(assign);
}
// iterative step
double deltaR2, distphi;
vector<double> ynom, phinom, den;
ynom.resize(axes.size());
phinom.resize(axes.size());
den.resize(axes.size());
for (size_t i = 0; i < particles.size(); i++) {
distphi = particles[i].phi() - axes[belongsto[i]].phi();
deltaR2 = particles[i].squared_distance(axes[belongsto[i]]);
if (deltaR2 == 0.) continue;
if (abs(distphi) <= M_PI) phinom.at(belongsto[i]) += particles[i].perp() * particles[i].phi() * pow(deltaR2, (beta-2)/2);
else if ( distphi > M_PI) phinom.at(belongsto[i]) += particles[i].perp() * (-2 * M_PI + particles[i].phi()) * pow(deltaR2, (beta-2)/2);
else if ( distphi < M_PI) phinom.at(belongsto[i]) += particles[i].perp() * (+2 * M_PI + particles[i].phi()) * pow(deltaR2, (beta-2)/2);
ynom.at(belongsto[i]) += particles[i].perp() * particles[i].rap() * pow(deltaR2, (beta-2)/2);
den.at(belongsto[i]) += particles[i].perp() * pow(deltaR2, (beta-2)/2);
}
// reset to new axes
for (size_t j = 0; j < axes.size(); j++) {
if (den[j] == 0.) axes.at(j) = axes[j];
else {
double phi_new = fmod( 2*M_PI + (phinom[j] / den[j]), 2*M_PI );
double pt_new = axes[j].perp();
double y_new = ynom[j] / den[j];
double px = pt_new * cos(phi_new);
double py = pt_new * sin(phi_new);
double pz = pt_new * sinh(y_new);
axes.at(j).reset(px, py, pz, axes[j].perp()/2);
}
}
}
void init() {
/// Projections:
FinalState fs((Cuts::etaIn(-4.5, 4.5) && Cuts::pT >= 0.*GeV));
declare(fs, "FS");
declare(FastJets(fs, FastJets::ANTIKT, 1.0), "AKT");
declare(FastJets(fs, FastJets::CAM, 1.2) , "CA" );
/// Histograms:
{Histo1DPtr tmp; _h_camass.add(200, 300, book(tmp, 1, 1, 1));}
{Histo1DPtr tmp; _h_camass.add(300, 400, book(tmp, 2, 1, 1));}
{Histo1DPtr tmp; _h_camass.add(400, 500, book(tmp, 3, 1, 1));}
{Histo1DPtr tmp; _h_camass.add(500, 600, book(tmp, 4, 1, 1));}
{Histo1DPtr tmp; _h_filtmass.add(200, 300, book(tmp, 5, 1, 1));}
{Histo1DPtr tmp; _h_filtmass.add(300, 400, book(tmp, 6, 1, 1));}
{Histo1DPtr tmp; _h_filtmass.add(400, 500, book(tmp, 7, 1, 1));}
{Histo1DPtr tmp; _h_filtmass.add(500, 600, book(tmp, 8, 1, 1));}
{Histo1DPtr tmp; _h_ktmass.add(200, 300, book(tmp, 9, 1, 1));}
{Histo1DPtr tmp; _h_ktmass.add(300, 400, book(tmp, 10, 1, 1));}
{Histo1DPtr tmp; _h_ktmass.add(400, 500, book(tmp, 11, 1, 1));}
{Histo1DPtr tmp; _h_ktmass.add(500, 600, book(tmp, 12, 1, 1));}
{Histo1DPtr tmp; _h_ktd12.add(200, 300, book(tmp, 13, 1, 1));}
{Histo1DPtr tmp; _h_ktd12.add(300, 400, book(tmp, 14, 1, 1));}
{Histo1DPtr tmp; _h_ktd12.add(400, 500, book(tmp, 15, 1, 1));}
{Histo1DPtr tmp; _h_ktd12.add(500, 600, book(tmp, 16, 1, 1));}
{Histo1DPtr tmp; _h_ktd23.add(200, 300, book(tmp, 17, 1 ,1));}
{Histo1DPtr tmp; _h_ktd23.add(300, 400, book(tmp, 18, 1 ,1));}
{Histo1DPtr tmp; _h_ktd23.add(400, 500, book(tmp, 19, 1 ,1));}
{Histo1DPtr tmp; _h_ktd23.add(500, 600, book(tmp, 20, 1 ,1));}
{Histo1DPtr tmp; _h_cat21.add(200, 300, book(tmp, 21, 1, 1));}
{Histo1DPtr tmp; _h_cat21.add(300, 400, book(tmp, 22, 1, 1));}
{Histo1DPtr tmp; _h_cat21.add(400, 500, book(tmp, 23, 1, 1));}
{Histo1DPtr tmp; _h_cat21.add(500, 600, book(tmp, 24, 1, 1));}
{Histo1DPtr tmp; _h_cat32.add(200, 300, book(tmp, 25, 1, 1));}
{Histo1DPtr tmp; _h_cat32.add(300, 400, book(tmp, 26, 1, 1));}
{Histo1DPtr tmp; _h_cat32.add(400, 500, book(tmp, 27, 1, 1));}
{Histo1DPtr tmp; _h_cat32.add(500, 600, book(tmp, 28, 1, 1));}
{Histo1DPtr tmp; _h_ktt21.add(200, 300, book(tmp, 29, 1, 1));}
{Histo1DPtr tmp; _h_ktt21.add(300, 400, book(tmp, 30, 1, 1));}
{Histo1DPtr tmp; _h_ktt21.add(400, 500, book(tmp, 31, 1, 1));}
{Histo1DPtr tmp; _h_ktt21.add(500, 600, book(tmp, 32, 1, 1));}
{Histo1DPtr tmp; _h_ktt32.add(200, 300, book(tmp, 33, 1, 1));}
{Histo1DPtr tmp; _h_ktt32.add(300, 400, book(tmp, 34, 1, 1));}
{Histo1DPtr tmp; _h_ktt32.add(400, 500, book(tmp, 35, 1, 1));}
{Histo1DPtr tmp; _h_ktt32.add(500, 600, book(tmp, 36, 1, 1));}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const double weight = 1.0;
using namespace fastjet;
// Get anti-kt jets with p_T > 200 GeV, check abs(y) < 2, and fill mass histograms
const FastJets& ktfj = apply<FastJets>(event, "AKT");
PseudoJets ktjets = ktfj.pseudoJetsByPt(200*GeV);
for (const PseudoJet & ajet : ktjets) {
if (abs(ajet.rap()) < 2) {
_h_ktmass.fill(ajet.perp(), ajet.m(), weight);
}
}
// Same as above but C/A jets
const FastJets& cafj = apply<FastJets>(event, "CA");
PseudoJets cajets = cafj.pseudoJetsByPt(200*GeV);
for (const PseudoJet & ajet : cajets) {
if (abs(ajet.rap()) < 2) {
_h_camass.fill(ajet.perp(), ajet.m(), weight);
}
}
// Split and filter.
// Only do this to C/A jets in this analysis.
for (const PseudoJet & pjet : cajets) {
if ( pjet.perp() > 600 || abs(pjet.rap()) > 2) continue;
double dR = 0;
bool unclustered = false;
PseudoJets split_jets = splitjet(pjet, dR, cafj, unclustered);
if ( (dR < 0.15) || (unclustered == false) ) continue;
PseudoJet filt_jet = filterjet(split_jets, dR, 0.3);
_h_filtmass.fill(filt_jet.perp(), filt_jet.m(), weight);
}
// Use the two last stages of clustering to get sqrt(d_12) and sqrt(d_23).
// Only use anti-kt jets in this analysis.
for (const PseudoJet & pjet : ktjets) {
if (pjet.perp() > 600 || abs(pjet.rap()) > 2) continue;
ClusterSequence subjet_cseq(ktfj.clusterSeq()->constituents(pjet), JetDefinition(kt_algorithm, M_PI/2.));
double d_12 = subjet_cseq.exclusive_dmerge(1) * M_PI*M_PI/4.;
double d_23 = subjet_cseq.exclusive_dmerge(2) * M_PI*M_PI/4.;
_h_ktd12.fill(pjet.perp(), sqrt(d_12), weight);
_h_ktd23.fill(pjet.perp(), sqrt(d_23), weight);
}
// N-subjettiness, use beta = 1 (no rationale given).
// Uses the functions defined above.
// C/A jets first, anti-kt after.
double beta = 1.;
//Rcut is used for particles that are very far from the closest axis. At 10
//is has no impact on the outcome of the calculation
double Rcut = 10.;
for (const PseudoJet & pjet : cajets) {
if (pjet.perp() > 600*GeV || fabs(pjet.rap()) > 2) continue;
const PseudoJets constituents = cafj.clusterSeq()->constituents(pjet);
if (constituents.size() < 3) continue;
const PseudoJets axis1 = jetGetAxes(1, constituents, M_PI/2.0);
const PseudoJets axis2 = jetGetAxes(2, constituents, M_PI/2.0);
const PseudoJets axis3 = jetGetAxes(3, constituents, M_PI/2.0);
const double radius = 1.2;
const double tau1 = jetTauValue(beta, radius, constituents, axis1, Rcut);
const double tau2 = jetTauValue(beta, radius, constituents, axis2, Rcut);
const double tau3 = jetTauValue(beta, radius, constituents, axis3, Rcut);
if (tau1 == 0 || tau2 == 0) continue;
_h_cat21.fill(pjet.perp(), tau2/tau1, weight);
_h_cat32.fill(pjet.perp(), tau3/tau2, weight);
}
for (const PseudoJet & pjet : ktjets) {
if (pjet.perp() > 600*GeV || fabs(pjet.rap()) > 2) continue;
const PseudoJets constituents = ktfj.clusterSeq()->constituents(pjet);
if (constituents.size() < 3) continue;
const PseudoJets axis1 = jetGetAxes(1, constituents, M_PI/2.0);
const PseudoJets axis2 = jetGetAxes(2, constituents, M_PI/2.0);
const PseudoJets axis3 = jetGetAxes(3, constituents, M_PI/2.0);
const double radius = 1.0;
const double tau1 = jetTauValue(beta, radius, constituents, axis1, Rcut);
const double tau2 = jetTauValue(beta, radius, constituents, axis2, Rcut);
const double tau3 = jetTauValue(beta, radius, constituents, axis3, Rcut);
if (tau1 == 0 || tau2 == 0) continue;
_h_ktt21.fill(pjet.perp(), tau2/tau1, weight);
_h_ktt32.fill(pjet.perp(), tau3/tau2, weight);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for (Histo1DPtr h : _h_camass.histos()) normalize(h);
for (Histo1DPtr h : _h_filtmass.histos()) normalize(h);
for (Histo1DPtr h : _h_ktmass.histos()) normalize(h);
for (Histo1DPtr h : _h_ktd12.histos()) normalize(h);
for (Histo1DPtr h : _h_ktd23.histos()) normalize(h);
for (Histo1DPtr h : _h_cat21.histos()) normalize(h);
for (Histo1DPtr h : _h_cat32.histos()) normalize(h);
for (Histo1DPtr h : _h_ktt21.histos()) normalize(h);
for (Histo1DPtr h : _h_ktt32.histos()) normalize(h);
}
private:
BinnedHistogram _h_camass;
BinnedHistogram _h_filtmass;
BinnedHistogram _h_ktmass;
BinnedHistogram _h_ktd12;
BinnedHistogram _h_ktd23;
BinnedHistogram _h_cat21;
BinnedHistogram _h_cat32;
BinnedHistogram _h_ktt21;
BinnedHistogram _h_ktt32;
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ATLAS_2012_I1094564);
}
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