// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief Lambda_c+ -> Lambda eta pi+
class BESIII_2019_I1711896 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1711896);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==4122);
declare(ufs, "UFS");
DecayedParticles LAMBDAC(ufs);
LAMBDAC.addStable(PID::PI0);
LAMBDAC.addStable(PID::K0S);
LAMBDAC.addStable(PID::ETA);
LAMBDAC.addStable(PID::ETAPRIME);
LAMBDAC.addStable(PID::LAMBDA);
declare(LAMBDAC, "LAMBDAC");
// histograms
book(_h,1,1,1);
book(_dalitz, "dalitz",50,1.5,3.5,50,2.5,5.0);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1},{ 221,1}, { PID::LAMBDA,1}};
static const map<PdgId,unsigned int> & modeCC = { {-211,1},{ 221,1}, {-PID::LAMBDA,1}};
DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
// loop over particles
for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
int sign = 1;
if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
sign=1;
}
else if (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
sign=-1;
}
else
continue;
const Particles & lam = LAMBDAC.decayProducts()[ix].at( sign*PID::LAMBDA);
const Particles & pip = LAMBDAC.decayProducts()[ix].at( sign*PID::PIPLUS);
const Particles & eta = LAMBDAC.decayProducts()[ix].at( PID::ETA);
double mLamPi = (lam[0].momentum()+pip[0].momentum()).mass2();
double mLamEta = (lam[0].momentum()+eta[0].momentum()).mass2();
_dalitz ->fill(mLamPi,mLamEta);
_h->fill(sqrt(mLamPi));
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h);
normalize(_dalitz );
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h;
Histo2DPtr _dalitz;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2019_I1711896);
}