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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Add a short analysis description here
class BESIII_2018_I1641075 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1641075);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_m, 1, 1, 5);
}
void findDecayProducts(const Particle & mother, unsigned int & nstable, unsigned int & ngamma,
unsigned int & npip, unsigned int & npim, FourMomentum & ptot) {
for(const Particle & p : mother.children()) {
int id = p.pid();
if (id == PID::PIMINUS ) {
++npim;
++nstable;
ptot += p.momentum();
}
else if (id == PID::PIPLUS) {
++npip;
++nstable;
ptot += p.momentum();
}
else if ( !p.children().empty() ) {
findDecayProducts(p, nstable, ngamma,npip,npim,ptot);
}
else if (id == PID::GAMMA) {
++ngamma;
++nstable;
}
else
++nstable;
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Loop over eta' mesons
for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==331)) {
unsigned nstable(0),ngamma(0),npip(0),npim(0);
FourMomentum ptot;
findDecayProducts(p,nstable,ngamma,npip,npim,ptot);
if(nstable==3 && npim==1 && npip==1 && ngamma==1)
_h_m->fill(ptot.mass());
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_m);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_m;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(BESIII_2018_I1641075);
}
|