// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief Lambda_c+ -> p K0S eta
class BESIII_2021_I1837968 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1837968);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==4122);
declare(ufs, "UFS");
DecayedParticles LAMBDAC(ufs);
LAMBDAC.addStable(PID::PI0);
LAMBDAC.addStable(PID::K0S);
LAMBDAC.addStable(PID::ETA);
declare(LAMBDAC, "LAMBDAC");
// histograms
for(unsigned int ix=0;ix<3;++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 = { { PID::PROTON,1}, {310,1}, { 221,1}};
static const map<PdgId,unsigned int> & modeCC = { {-PID::PROTON,1}, {310,1}, { 221,1}};
DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
// loop over particles
for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
int sign = 1;
if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
sign=1;
}
else if (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
sign=-1;
}
else
continue;
const Particle & pp = LAMBDAC.decayProducts()[ix].at( sign*PID::PROTON)[0];
const Particle & eta = LAMBDAC.decayProducts()[ix].at( 221)[0];
const Particle & K0 = LAMBDAC.decayProducts()[ix].at( 310)[0];
_h[0]->fill((pp.momentum()+ K0.momentum()).mass());
_h[1]->fill((K0.momentum()+eta.momentum()).mass());
_h[2]->fill((pp.momentum()+eta.momentum()).mass());
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<3;++ix)
normalize(_h[ix]);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[3];
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2021_I1837968);
}