// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief B0 -> K+ K- KS0
class BELLE_2010_I862241 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I862241);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==511);
declare(ufs, "UFS");
DecayedParticles B0(ufs);
B0.addStable(PID::K0S);
declare(B0, "B0");
// histograms
for(unsigned int ix=0;ix<4;++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 = { { 321,1}, {-321,1}, { 310,1}};
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()>0 ? 1 : -1;
const Particle & Kp = B0.decayProducts()[ix].at( 321*sign)[0];
const Particle & Km = B0.decayProducts()[ix].at(-321*sign)[0];
const Particle & K0 = B0.decayProducts()[ix].at( 310 )[0];
_h[0]->fill((K0.momentum()+Kp.momentum()).mass());
_h[1]->fill((K0.momentum()+Km.momentum()).mass());
_h[2]->fill((Km.momentum()+Kp.momentum()).mass());
_h[3]->fill((Km.momentum()+Kp.momentum()).mass());
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<4;++ix)
normalize(_h[ix],1.);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[4];
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2010_I862241);
}