// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief J/psi and psi(2S) -> pi+pi-pi0
class BESIII_2012_I1088606 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2012_I1088606);
/// @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::PI0);
psi.addStable(PID::K0S);
psi.addStable(PID::ETA);
psi.addStable(PID::ETAPRIME);
declare(psi, "psi");
book(_h_pipi[0],1,1,1);
book(_h_pipi[1],1,1,2);
book(_dalitz[0], "dalitz_Jpsi" ,50,0.,9. ,50,0.0, 9.);
book(_dalitz[1], "dalitz_psi2S",50,0.,14.,50,0.0,14.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1}, {-211,1}, { 111,1} };
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 Particles & pi0 = psi.decayProducts()[ix].at( 111);
const Particles & pip = psi.decayProducts()[ix].at( 211);
const Particles & pim = psi.decayProducts()[ix].at(-211);
double mminus = (pim[0].momentum()+pi0[0].momentum()).mass2();
double mplus = (pip[0].momentum()+pi0[0].momentum()).mass2();
double mneut = (pip[0].momentum()+pim[0].momentum()).mass2();
unsigned int iloc = psi.decaying()[ix].pid()/100000;
_h_pipi[iloc]->fill(sqrt(mneut ));
_h_pipi[iloc]->fill(sqrt(mplus ));
_h_pipi[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(_dalitz[ix]);
}
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_pipi[2];
Histo2DPtr _dalitz[2];
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2012_I1088606);
}