// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D_s+ -> pi+ pi+ pi- eta
class BESIII_2021_I1870322 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1870322);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==431);
declare(ufs, "UFS");
DecayedParticles DS(ufs);
DS.addStable(PID::PI0);
DS.addStable(PID::K0S);
DS.addStable(PID::ETA);
declare(DS,"DS");
// histograms
book(_h_pippip ,1,1,1);
book(_h_pippim ,1,1,2);
book(_h_pipeta ,1,1,3);
book(_h_pimeta ,1,1,4);
book(_h_3pi ,1,1,5);
book(_h_pippimeta,1,1,6);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,2}, {-211,1}, {221,1}};
static const map<PdgId,unsigned int> & modeCC = { { 211,1}, {-211,2}, {221,1}};
DecayedParticles DS = apply<DecayedParticles>(event, "DS");
// loop over particles
for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
int sign = 1;
if (DS.decaying()[ix].pid()>0 && DS.modeMatches(ix,4,mode)) {
sign=1;
}
else if (DS.decaying()[ix].pid()<0 && DS.modeMatches(ix,4,modeCC)) {
sign=-1;
}
else
continue;
const Particles & pip = DS.decayProducts()[ix].at( sign*211);
const Particle & pim = DS.decayProducts()[ix].at(-sign*211)[0];
const Particle & eta = DS.decayProducts()[ix].at( 221)[0];
double metapipi[2] = {(eta.momentum()+pim.momentum()+pip[0].momentum()).mass(),
(eta.momentum()+pim.momentum()+pip[1].momentum()).mass()};
if(metapipi[0]<GeV || metapipi[1]<GeV) continue;
_h_pippip->fill((pip[0].momentum()+pip[1].momentum()).mass());
_h_pippim->fill((pim.momentum()+pip[0].momentum()).mass());
_h_pippim->fill((pim.momentum()+pip[1].momentum()).mass());
_h_pipeta->fill((eta.momentum()+pip[0].momentum()).mass());
_h_pipeta->fill((eta.momentum()+pip[1].momentum()).mass());
_h_pimeta->fill((eta.momentum()+pim.momentum()).mass());
_h_3pi ->fill((pim.momentum()+pip[0].momentum()+pip[1].momentum()).mass());
_h_pippimeta->fill(metapipi[0]);
_h_pippimeta->fill(metapipi[1]);
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_pippip );
normalize(_h_pippim );
normalize(_h_pipeta );
normalize(_h_pimeta );
normalize(_h_3pi );
normalize(_h_pippimeta);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_pippip,_h_pippim,_h_pipeta,_h_pimeta,_h_3pi,_h_pippimeta;
/// @}
};
RIVET_DECLARE_PLUGIN(BESIII_2021_I1870322);
}