// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D_s+ -> pi+ pi0 eta'
class BESIII_2022_I2030993 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2030993);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==431);
declare(ufs, "UFS");
DecayedParticles DS(ufs);
DS.addStable(PID::PI0);
DS.addStable(PID::K0S);
DS.addStable(PID::ETAPRIME);
declare(DS,"DS");
// histograms
book(_h_etapip,1,1,1);
book(_h_etapi0,1,1,2);
book(_h_pipi , 1,1,3);
book(_dalitz, "dalitz",50,0.,1.1,50,1,3.5);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1}, { 111,1}, { 331,1}};
static const map<PdgId,unsigned int> & modeCC = { {-211,1}, { 111,1}, { 331,1}};
DecayedParticles DS = apply<DecayedParticles>(event, "DS");
// loop over particles
for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
int sign = 1;
if (DS.decaying()[ix].pid()>0 && DS.modeMatches(ix,3,mode)) {
sign=1;
}
else if (DS.decaying()[ix].pid()<0 && DS.modeMatches(ix,3,modeCC)) {
sign=-1;
}
else
continue;
const Particle & pip = DS.decayProducts()[ix].at( sign*211)[0];
const Particle & pi0 = DS.decayProducts()[ix].at( 111)[0];
const Particle & eta = DS.decayProducts()[ix].at( 331)[0];
double mplus = (eta.momentum()+pip.momentum()).mass2();
double mzero = (eta.momentum()+pi0.momentum()).mass2();
double mpipi = (pip.momentum()+pi0.momentum()).mass2();
_dalitz ->fill(mpipi,mplus);
_h_pipi ->fill(sqrt(mpipi));
_h_etapip->fill(sqrt(mplus));
_h_etapi0->fill(sqrt(mzero));
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_pipi );
normalize(_h_etapip);
normalize(_h_etapi0);
normalize(_dalitz );
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_pipi, _h_etapip,_h_etapi0;
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2022_I2030993);
}