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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
namespace Rivet {
/// @brief DELPHI b-fragmentation measurement
///
/// @author Hendrik Hoeth
class ALEPH_2001_S4656318 : public Analysis {
public:
RIVET_DEFAULT_ANALYSIS_CTOR(ALEPH_2001_S4656318);
/// @name Analysis methods
/// @{
/// Book projections and histograms
void init() {
declare(Beam(), "Beams");
declare(ChargedFinalState(), "FS");
book(_histXbweak ,1, 1, 1);
book(_histXbprim ,1, 1, 2);
book(_histMeanXbweak ,7, 1, 1);
book(_histMeanXbprim ,7, 1, 2);
}
/// Analyse each event
void analyze(const Event& e) {
const FinalState& fs = apply<FinalState>(e, "FS");
const size_t numParticles = fs.particles().size();
// Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
if (numParticles < 2) {
MSG_DEBUG("Failed ncharged cut");
vetoEvent;
}
MSG_DEBUG("Passed ncharged cut");
// Get beams and average beam momentum
const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
const double meanBeamMom = ( beams.first.p3().mod() +
beams.second.p3().mod() ) / 2.0;
MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
for(ConstGenParticlePtr p : HepMCUtils::particles(e.genEvent())) {
ConstGenVertexPtr pv = p->production_vertex();
ConstGenVertexPtr dv = p->end_vertex();
if (PID::isBottomHadron(p->pdg_id())) {
const double xp = p->momentum().e()/meanBeamMom;
// If the B-hadron has a parton as parent, call it primary B-hadron:
if (pv) {
bool is_primary = false;
for (ConstGenParticlePtr pp: HepMCUtils::particles(pv, Relatives::PARENTS)){
if (isParton(pp->pdg_id())) is_primary = true;
}
if (is_primary) {
_histXbprim->fill(xp);
_histMeanXbprim->fill(_histMeanXbprim->bin(0).xMid(), xp);
}
}
// If the B-hadron has no B-hadron as a child, it decayed weakly:
if (dv) {
bool is_weak = true;
for (ConstGenParticlePtr pp: HepMCUtils::particles(dv, Relatives::CHILDREN)){
if (PID::isBottomHadron(pp->pdg_id())) {
is_weak = false;
}
}
if (is_weak) {
_histXbweak->fill(xp);
_histMeanXbweak->fill(_histMeanXbweak->bin(0).xMid(), xp);
}
}
}
}
}
/// Finalize the histograms
void finalize() {
normalize(_histXbprim);
normalize(_histXbweak);
}
/// @}
/// @name Helper functions
/// @note The PID:: namespace functions would be preferable, but don't have exactly the same behaviour. Preserving the original form.
/// @{
bool isParton(int id) { return abs(id) <= 100 && abs(id) != 22 && (abs(id) < 11 || abs(id) > 18); }
// bool isBHadron(int id) { return ((abs(id)/100)%10 == 5) || (abs(id) >= 5000 && abs(id) <= 5999); }
/// @}
/// @name Histograms
///
/// Store the weighted sums of numbers of charged / charged+neutral
/// particles - used to calculate average number of particles for the
/// inclusive single particle distributions' normalisations.
/// @{
Histo1DPtr _histXbprim;
Histo1DPtr _histXbweak;
Profile1DPtr _histMeanXbprim;
Profile1DPtr _histMeanXbweak;
/// @}
};
RIVET_DECLARE_ALIASED_PLUGIN(ALEPH_2001_S4656318, ALEPH_2001_I558327);
}
|