// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D+ -> K+ KS0 pi0
class BESIII_2021_I1859124 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1859124);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==411);
declare(ufs, "UFS");
DecayedParticles DP(ufs);
DP.addStable(PID::PI0);
DP.addStable(PID::K0S);
declare(DP,"DP");
// histos
book(_h_Kppi0,1,1,1);
book(_h_K0pi0,1,1,2);
book(_h_KpK0,1,1,3);
book(_dalitz, "dalitz",50,0.3,2.,50,0.3,2.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 321,1},{ 111,1}, {310,1}};
static const map<PdgId,unsigned int> & modeCC = { {-321,1},{ 111,1}, {310,1}};
DecayedParticles DP = apply<DecayedParticles>(event, "DP");
// loop over particles
for(unsigned int ix=0;ix<DP.decaying().size();++ix) {
int sign = 1;
if (DP.decaying()[ix].pid()>0 && DP.modeMatches(ix,3,mode)) {
sign=1;
}
else if (DP.decaying()[ix].pid()<0 && DP.modeMatches(ix,3,modeCC)) {
sign=-1;
}
else
continue;
const Particle & K0 = DP.decayProducts()[ix].at( 310)[0];
const Particle & pi0 = DP.decayProducts()[ix].at( 111)[0];
const Particle & Kp = DP.decayProducts()[ix].at( sign*321)[0];
double mplus = (Kp.momentum() +pi0.momentum()).mass2();
double mneut = (K0.momentum() +pi0.momentum()).mass2();
double mKK = (Kp.momentum() + K0.momentum()).mass2();
_h_Kppi0->fill(sqrt(mplus));
_h_K0pi0->fill(sqrt(mneut));
_h_KpK0 ->fill(sqrt(mKK ));
_dalitz ->fill(mplus,mneut);
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_Kppi0);
normalize(_h_K0pi0);
normalize(_h_KpK0 );
normalize(_dalitz );
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_Kppi0,_h_K0pi0,_h_KpK0;
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2021_I1859124);
}