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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/NeutralFinalState.hh"
#include "Rivet/Projections/MergedFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "fastjet/SISConePlugin.hh"
namespace Rivet {
/// @brief STAR underlying event
/// @author Hendrik Hoeth
class STAR_2009_UE_HELEN : public Analysis {
public:
/// Constructor
STAR_2009_UE_HELEN()
: Analysis("STAR_2009_UE_HELEN")
{
}
/// @name Analysis methods
//@{
void init() {
// Charged final state, |eta|<1, pT>0.2GeV
const Cut c = Cuts::etaIn(-1.0, 1.0) && Cuts::pT >= 0.2*GeV;
const ChargedFinalState cfs(c);
declare(cfs, "CFS");
// Neutral final state, |eta|<1, ET>0.2GeV (needed for the jets)
const NeutralFinalState nfs(c);
declare(nfs, "NFS");
// STAR can't see neutrons and K^0_L
VetoedFinalState vfs(nfs);
vfs.vetoNeutrinos();
vfs.addVetoPairId(PID::K0L);
vfs.addVetoPairId(PID::NEUTRON);
declare(vfs, "VFS");
// Jets are reconstructed from charged and neutral particles,
// and the cuts are different (pT vs. ET), so we need to merge them.
const MergedFinalState jfs(cfs, vfs);
declare(jfs, "JFS");
// SISCone, R = 0.7, overlap_threshold = 0.75
declare(FastJets(jfs, FastJets::SISCONE, 0.7), "AllJets");
// Book histograms
book(_hist_pmaxnchg , 1, 1, 1);
book(_hist_pminnchg , 2, 1, 1);
book(_hist_anchg , 3, 1, 1);
}
// Do the analysis
void analyze(const Event& e) {
const FinalState& cfs = apply<ChargedFinalState>(e, "CFS");
if (cfs.particles().size() < 1) {
MSG_DEBUG("Failed multiplicity cut");
vetoEvent;
}
const Jets& alljets = apply<FastJets>(e, "AllJets").jetsByPt();
MSG_DEBUG("Total jet multiplicity = " << alljets.size());
// The jet acceptance region is |eta|<(1-R)=0.3 (with R = jet radius)
// Jets also must have a neutral energy fraction of < 0.7
Jets jets;
for (const Jet & jet : alljets) {
if (jet.neutralEnergy()/jet.totalEnergy() < 0.7 &&
jet.abseta() < 0.3)
jets.push_back(jet);
}
// This analysis requires a di-jet like event.
// WARNING: There is more data in preparation, some of which
// does _not_ have this constraint!
if (jets.size() != 2) {
MSG_DEBUG("Failed jet multiplicity cut");
vetoEvent;
}
// The di-jet constraints in this analysis are:
// - 2 and only 2 jets in the acceptance region
// - delta(Phi) between the jets is > 150 degrees
// - Pt_awayjet/Pt_towards_jet > 0.7
if (deltaPhi(jets[0].phi(), jets[1].phi()) <= 5*PI/6 ||
jets[1].pT()/jets[0].pT() <= 0.7)
{
MSG_DEBUG("Failed di-jet criteria");
vetoEvent;
}
// Now lets start ...
const double jetphi = jets[0].phi();
const double jetpT = jets[0].pT();
size_t numTrans1(0), numTrans2(0), numAway(0);
// Calculate all the charged stuff
for (const Particle& p : cfs.particles()) {
const double dPhi = deltaPhi(p.phi(), jetphi);
const double pT = p.pT();
const double phi = p.phi();
double rotatedphi = phi - jetphi;
while (rotatedphi < 0) rotatedphi += 2*PI;
// @TODO: WARNING: The following lines are a hack to correct
// for the STAR tracking efficiency. Once we have the
// final numbers (corrected to hadron level), we need
// to remove this!!!!
if (1.0*rand()/static_cast<double>(RAND_MAX) > 0.87834-exp(-1.48994-0.788432*pT)) {
continue;
}
// -------- end of efficiency hack -------
if (dPhi < PI/3.0) {
// toward
}
else if (dPhi < 2*PI/3.0) {
if (rotatedphi <= PI) {
++numTrans1;
}
else {
++numTrans2;
}
}
else {
++numAway;
}
} // end charged particle loop
// Fill the histograms
_hist_pmaxnchg->fill(jetpT, (numTrans1>numTrans2 ? numTrans1 : numTrans2)/(2*PI/3));
_hist_pminnchg->fill(jetpT, (numTrans1<numTrans2 ? numTrans1 : numTrans2)/(2*PI/3));
_hist_anchg->fill(jetpT, numAway/(PI*0.7*0.7)); // jet area = pi*R^2
}
void finalize() {
//
}
//@}
private:
Profile1DPtr _hist_pmaxnchg;
Profile1DPtr _hist_pminnchg;
Profile1DPtr _hist_anchg;
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(STAR_2009_UE_HELEN);
}
|