// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief J/psi -> K+K-pi0
class BESIII_2019_I1731057 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1731057);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid== 443);
declare(ufs, "UFS");
DecayedParticles PSI(ufs);
PSI.addStable(PID::PI0);
declare(PSI,"PSI");
// histos
for(unsigned int ix=0;ix<2;++ix) {
book(_h_KpKm [ix],1+ix,1,1);
book(_h_Kppi0[ix],1+ix,1,2);
}
book(_dalitz, "dalitz",50,0.,7.,50,0.0,7.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 321,1},{-321,1}, {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 Particle & Kp = PSI.decayProducts()[ix].at( 321)[0];
const Particle & Km = PSI.decayProducts()[ix].at(-321)[0];
const Particle & pi0 = PSI.decayProducts()[ix].at( 111)[0];
double mminus = (Km.momentum()+pi0.momentum()).mass2();
double mplus = (Kp.momentum()+pi0.momentum()).mass2();
double mneut = (Kp.momentum()+Km.momentum()).mass2();
_dalitz->fill(mplus,mminus);
mplus=sqrt(mplus);
mminus=sqrt(mminus);
mneut=sqrt(mneut);
_h_KpKm [0]->fill(mneut );
_h_Kppi0[0]->fill(mplus );
_h_Kppi0[0]->fill(mminus);
if(mplus>1.05 && mminus>1.05) {
_h_KpKm [1]->fill(mneut );
_h_Kppi0[1]->fill(mplus );
_h_Kppi0[1]->fill(mminus);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<2;++ix) {
normalize(_h_KpKm [ix],1.,false);
normalize(_h_Kppi0[ix],1.,false);
}
normalize(_dalitz);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_KpKm[2],_h_Kppi0[2];
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2019_I1731057);
}