// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D0 -> K- pi+ e+e-
class BABAR_2019_I1691954 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2019_I1691954);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==421);
declare(ufs, "UFS");
DecayedParticles D0(ufs);
D0.addStable(PID::PI0);
D0.addStable(PID::K0S);
declare(D0, "D0");
for(unsigned int ix=0;ix<2;++ix)
book(_h[ix],1,1,1+ix);
book(_h[2],2,1,1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { {-321,1}, { 211,1}, {11,1}, {-11,1} };
static const map<PdgId,unsigned int> & modeCC = { { 321,1}, {-211,1}, {11,1}, {-11,1} };
DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
// loop over particles
for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
int sign = 1;
if (D0.decaying()[ix].pid()>0 && D0.modeMatches(ix,4,mode)) {
sign=1;
}
else if (D0.decaying()[ix].pid()<0 && D0.modeMatches(ix,4,modeCC)) {
sign=-1;
}
else
continue;
const Particle & Kp = D0.decayProducts()[ix].at(-sign*321)[0];
const Particle & pim = D0.decayProducts()[ix].at( sign*211)[0];
const Particle & ep = D0.decayProducts()[ix].at( 11)[0];
const Particle & em = D0.decayProducts()[ix].at(-11)[0];
double mee = (em.momentum()+ep.momentum()).mass();
if(mee>0.675 && mee<0.875) {
_h[1]->fill((Kp.momentum()+pim.momentum()).mass());
_h[0]->fill(mee);
}
if(mee>.2) _h[2]->fill(mee);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<3;++ix)
normalize(_h[ix],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[3];
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2019_I1691954);
}