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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Excited Lambda_c spectra
class ARGUS_1997_I440304 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1997_I440304);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// projections
declare(Beam(), "Beams");
declare(UnstableParticles(), "UFS");
// book histos
book(_h_rate1,1,1,1);
book(_h_rate2,1,2,1);
book(_h_x,2,1,1);
}
void findDecayProducts(Particle parent, Particles & Lambda_c, Particles & pions,unsigned int & nstable) {
for(const Particle & p : parent.children()) {
if(p.abspid()==4122) {
Lambda_c.push_back(p);
++nstable;
}
else if(p.abspid()==PID::PIPLUS) {
pions.push_back(p);
++nstable;
}
else if(!p.children().empty())
findDecayProducts(p,Lambda_c,pions,nstable);
else
++nstable;
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const int id2595 = 14122;
// Get beams and average beam momentum
const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
const double Emax = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
const double Pmax = sqrt(sqr(Emax)-sqr(2.595));
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::abspid==id2595)) {
// spectrum
double xp = p.momentum().p3().mod()/Pmax;
_h_x->fill(xp);
Particles Lambda_c,pions;
unsigned int nstable(0);
findDecayProducts(p,Lambda_c,pions,nstable);
if(nstable==3&&pions.size()==2&&Lambda_c.size()==1) {
_h_rate1->fill(xp);
_h_rate2->fill(xp);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_x);
// br for lambda_c mode from pdg 2018
double br = 0.0623;
scale(_h_rate1,0.3*br*crossSection()/sumOfWeights()/picobarn);
scale(_h_rate2, br*crossSection()/sumOfWeights()/picobarn);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_x,_h_rate1,_h_rate2;
///@}
};
RIVET_DECLARE_PLUGIN(ARGUS_1997_I440304);
}
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