// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief J/.psi anbd psi(2S) -> eta Sigma+ Sigmabar-
class BESIII_2022_I2166759 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2166759);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
UnstableParticles ufs = UnstableParticles(Cuts::pid==443 or
Cuts::pid==100443);
declare(ufs, "UFS");
DecayedParticles psi(ufs);
psi.addStable( PID::ETA);
psi.addStable( PID::SIGMAPLUS);
psi.addStable( PID::SIGMAMINUS);
psi.addStable(-PID::SIGMAPLUS);
psi.addStable(-PID::SIGMAMINUS);
declare(psi, "psi");
// histos
for(unsigned int ix=0;ix<6;++ix)
book(_h[ix],1,1,1+ix);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 3222,1}, {-3222,1}, { 221,1} };
DecayedParticles psi = apply<DecayedParticles>(event, "psi");
for(unsigned int ix=0;ix<psi.decaying().size();++ix) {
if(!psi.modeMatches(ix,3,mode)) continue;
unsigned int ioff = psi.decaying()[ix].pid()==443 ? 0 : 3;
const Particle & sigp = psi.decayProducts()[ix].at( 3222)[0];
const Particle & sigm = psi.decayProducts()[ix].at(-3222)[0];
const Particle & eta = psi.decayProducts()[ix].at( 221)[0];
_h[ioff+0]->fill((sigp.momentum()+eta .momentum()).mass());
_h[ioff+1]->fill((sigm.momentum()+eta .momentum()).mass());
_h[ioff+2]->fill((sigp.momentum()+sigm.momentum()).mass());
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<6;++ix)
normalize(_h[ix],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[6];
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2022_I2166759);
}