// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D0 -> pi+pi-pi0
class BABAR_2016_I1441203 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2016_I1441203);
/// @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);
D0.addStable(PID::ETA);
D0.addStable(PID::ETAPRIME);
declare(D0, "D0");
// histograms
book(_h_pi[0],1,1,1);
book(_h_pi[1],1,1,2);
book(_h_pi[2],1,1,3);
book(_dalitz, "dalitz",50,0.,3.2,50,0.0,3.2);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1},{-211,1}, {111,1}};
DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
// loop over particles
for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
if( ! D0.modeMatches(ix,3,mode) ) continue;
int sign = D0.decaying()[ix].pid()/421;
const Particles & pi0 = D0.decayProducts()[ix].at(111);
const Particles & pip = D0.decayProducts()[ix].at( sign*211);
const Particles & pim = D0.decayProducts()[ix].at(-sign*211);
double mneut = (pim[0].momentum()+pip[0].momentum()).mass2();
// if(mneut>475*MeV && mneut<505*MeV) continue;
double mplus = (pip[0].momentum()+pi0[0].momentum()).mass2();
double mminus = (pim[0].momentum()+pi0[0].momentum()).mass2();
_h_pi[0]->fill(mplus);
_h_pi[1]->fill(mminus);
_h_pi[2]->fill(mneut);
_dalitz->fill(mplus,mminus);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<3;++ix)
normalize(_h_pi[ix]);
normalize(_dalitz);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_pi[3];
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2016_I1441203);
}