// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief J/psi$ and psi(2S) to pi+ pi- eta'
class BESIII_2017_I1621266 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1621266);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid== 443 || Cuts::pid==100443);
declare(ufs, "UFS");
DecayedParticles PSI(ufs);
PSI.addStable(PID::ETAPRIME);
declare(PSI,"PSI");
// histos
book(_h_pipi [0],1,1,1);
book(_h_pieta[0],1,1,2);
book(_h_pipi [1],1,1,3);
book(_h_pieta[1],1,1,4);
book(_dalitz[0], "dalitz_Jpsi" ,50,1., 9.,50,1., 9.);
book(_dalitz[1], "dalitz_psi2S",50,1.,14.,50,1.,14.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1},{-211,1}, {331,1}};
DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
// loop over particles
for(unsigned int ix=0;ix<PSI.decaying().size();++ix) {
if (!PSI.modeMatches(ix,3,mode)) continue;
const Particle & pip = PSI.decayProducts()[ix].at( 211)[0];
const Particle & pim = PSI.decayProducts()[ix].at(-211)[0];
const Particle & eta = PSI.decayProducts()[ix].at( 331)[0];
unsigned int iloc = PSI.decaying()[ix].pid()/100000;
double mminus = (pim.momentum()+eta.momentum()).mass2();
double mplus = (pip.momentum()+eta.momentum()).mass2();
double mneut = (pip.momentum()+pim.momentum()).mass2();
_h_pipi[iloc] ->fill(sqrt(mneut ));
_h_pieta[iloc]->fill(sqrt(mplus ));
//_h_pieta[iloc]->fill(sqrt(mminus));
_dalitz[iloc]->fill(mplus,mminus);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<2;++ix) {
normalize(_h_pipi [ix]);
normalize(_h_pieta[ix]);
normalize(_dalitz [ix]);
}
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_pipi[2],_h_pieta[2];
Histo2DPtr _dalitz[2];
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2017_I1621266);
}