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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief phi -> eta pi0 gamma
class KLOE_2009_I818106 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(KLOE_2009_I818106);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
declare(UnstableParticles(), "UFS");
book(_h_etapi, 1, 1, 1);
book(_nPhi, "TMP/PhiCounter");
}
void findDecayProducts(const Particle & mother, unsigned int & nstable,
unsigned int & neta, unsigned int & npi,
unsigned int & ngamma, FourMomentum & ptot) {
for(const Particle & p : mother.children()) {
int id = p.pid();
if ( id == PID::ETA ) {
++neta;
++nstable;
ptot += p.momentum();
}
else if (id == PID::PI0) {
++npi;
++nstable;
ptot += p.momentum();
}
else if (id == PID::GAMMA) {
++ngamma;
++nstable;
}
else if (id == PID::PIPLUS || id == PID::PIMINUS) {
++nstable;
}
else if ( !p.children().empty() ) {
findDecayProducts(p, nstable, neta, npi, ngamma, ptot);
}
else
++nstable;
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Loop over phis
for(const Particle& phi : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==PID::PHI)) {
_nPhi->fill();
unsigned int nstable(0),neta(0),npi(0),ngamma(0);
FourMomentum p_tot(0,0,0,0);
findDecayProducts(phi, nstable, neta, npi, ngamma, p_tot);
if(nstable!=3) continue;
if(neta==1 && npi==1 && ngamma==1 ) {
_h_etapi->fill(p_tot.mass()/MeV);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// normalise to total no of phi mesons
// and mult by 10^7 due normalisation in paper
scale( _h_etapi, 1./_nPhi->sumW()*1e7);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_etapi;
CounterPtr _nPhi;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(KLOE_2009_I818106);
}
|