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SLD_2002_S4869273.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/RivetYODA.hh"
#include "Rivet/Tools/ParticleIdUtils.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
/// @todo Use inline PID functions instead
#define IS_PARTON_PDGID(id) ( abs(id) <= 100 && abs(id) != 22 && (abs(id) < 11 || abs(id) > 18) )
#define IS_BHADRON_PDGID(id) ( ((abs(id)/100)%10 == 5) || (abs(id) >= 5000 && abs(id) <= 5999) )
namespace Rivet {
/// @brief SLD b-fragmentation measurement
/// @author Peter Richardson
class SLD_2002_S4869273 : public Analysis {
public:
/// Constructor
SLD_2002_S4869273()
: Analysis("SLD_2002_S4869273")
{
}
/// @name Analysis methods
//@{
/// Book projections and histograms
void init() {
addProjection(Beam(), "Beams");
addProjection(ChargedFinalState(), "FS");
_histXbweak = bookHisto1D(1, 1, 1);
}
void analyze(const Event& e) {
const FinalState& fs = applyProjection<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 event weight for histo filling
const double weight = e.weight();
// Get beams and average beam momentum
const ParticlePair& beams = applyProjection<Beam>(e, "Beams").beams();
const double meanBeamMom = ( beams.first.momentum().vector3().mod() +
beams.second.momentum().vector3().mod() ) / 2.0;
MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
foreach (const GenParticle* p, particles(e.genEvent())) {
const GenVertex* dv = p->end_vertex();
if (IS_BHADRON_PDGID(p->pdg_id())) {
const double xp = p->momentum().e()/meanBeamMom;
// If the B-hadron has no B-hadron as a child, it decayed weakly:
if (dv) {
bool is_weak = true;
for (GenVertex::particles_out_const_iterator pp = dv->particles_out_const_begin() ;
pp != dv->particles_out_const_end() ; ++pp) {
if (IS_BHADRON_PDGID((*pp)->pdg_id())) {
is_weak = false;
}
}
if (is_weak) {
_histXbweak->fill(xp, weight);
}
}
}
}
}
// Finalize
void finalize() {
normalize(_histXbweak);
}
private:
/// 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 _histXbweak;
//@}
};
// The hook for the plugin system
DECLARE_RIVET_PLUGIN(SLD_2002_S4869273);
}

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