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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief tau -> K phi
class BELLE_2006_I725750 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2006_I725750);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
declare(UnstableParticles(), "UFS");
book(_hist, 1, 1, 1);
}
void findDecayProducts(const Particle & mother,
unsigned int & nstable,
Particles& phi, Particles& K) {
for(const Particle & p : mother.children()) {
long id = p.abspid();
if (id == PID::PHI ) {
phi.push_back(p);
++nstable;
}
else if (id == PID::KPLUS) {
K.push_back(p);
++nstable;
}
else if ( !p.children().empty() ) {
findDecayProducts(p, nstable, phi,K);
}
else
++nstable;
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::abspid==PID::TAU)) {
Particles phi, K;
unsigned int nstable = 0;
// find the decay products we want
findDecayProducts(p, nstable, phi, K);
if (nstable != 3) continue;
// K phi
if (K.size() == 1 && phi.size() == 1)
_hist->fill((phi[0].momentum()+K[0].momentum()).mass());
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_hist);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _hist;
///@}
};
RIVET_DECLARE_PLUGIN(BELLE_2006_I725750);
}
|