// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief Ds+ -> K+ pi+ pi-
class BESIII_2022_I2084294 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2084294);
/// @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::ETA);
DS.addStable(PID::ETAPRIME);
declare(DS, "DS");
// histograms
book(_h_Kpip,1,1,1);
book(_h_Kpim,1,1,2);
book(_h_pipi,1,1,3);
book(_dalitz,"dalitz",50,0.,2.3,50,0.3,3.5);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 321,1}, { 211,1},{-211,1}};
static const map<PdgId,unsigned int> & modeCC = { {-321,1}, {-211,1},{ 211,1}};
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 & Kp = DS.decayProducts()[ix].at( sign*321)[0];
const Particle & pip= DS.decayProducts()[ix].at( sign*211)[0];
const Particle & pim= DS.decayProducts()[ix].at(-sign*211)[0];
double mp = (Kp .momentum()+pip.momentum()).mass2();
double mm = (Kp .momentum()+pim.momentum()).mass2();
double mpipi = (pip.momentum()+pim.momentum()).mass2();
_dalitz->fill(mpipi,mm);
if(mpipi<sqr(.4676) || mpipi>sqr(0.5276)) {
_h_pipi->fill(sqrt(mpipi));
_h_Kpip->fill(sqrt(mp));
_h_Kpim->fill(sqrt(mm));
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_Kpip);
normalize(_h_Kpim);
normalize(_h_pipi);
normalize(_dalitz);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_Kpip,_h_Kpim,_h_pipi;
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2022_I2084294);
}