// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief B0 -> p pbar pi0
class BELLE_2019_I1729311 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2019_I1729311);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
UnstableParticles ufs = UnstableParticles(Cuts::abspid==511);
declare(ufs, "UFS");
DecayedParticles B0(ufs);
B0.addStable(PID::PI0);
B0.addStable(PID::K0S);
B0.addStable(PID::ETA);
B0.addStable(PID::ETAPRIME);
declare(B0, "B0");
book(_h[0],1,1,1);
for(unsigned int ix=0;ix<2;++ix)
book(_h[ix+1],2,1,1+ix);
book(_dalitz, "dalitz",50,1.,20.,50,1.,20.);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 2212,1}, {-2212,1}, { 111,1} };
DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
// loop over particles
for(unsigned int ix=0;ix<B0.decaying().size();++ix) {
if(!B0.modeMatches(ix,3,mode)) continue;
int sign = B0.decaying()[ix].pid()/511;
const Particle & pi0 = B0.decayProducts()[ix].at( 111)[0];
const Particle & pp = B0.decayProducts()[ix].at( sign*2212)[0];
const Particle & pbar = B0.decayProducts()[ix].at(-sign*2212)[0];
double mminus = (pbar.momentum()+pi0.momentum()).mass2();
double mplus = (pp .momentum()+pi0.momentum()).mass2();
_h[0]->fill((pp.momentum()+pbar.momentum()).mass());
_h[1]->fill(sqrt(mplus ));
_h[2]->fill(sqrt(mminus));
_dalitz->fill(mplus,mminus);
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_dalitz);
for(unsigned int ix=0;ix<3;++ix)
normalize(_h[ix]);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[3];
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2019_I1729311);
}