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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief D*2 spectrum and decay angle
class ARGUS_1989_I268577 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I268577);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_rate , 1, 1, 1);
book(_h_D2_x , 2, 1, 1);
book(_h_D2_ctheta, 3, 1, 1);
}
/// Recursively walk the decay tree to find decay products of @a p
void findDecayProducts(Particle mother, Particles & d, Particles & pi,unsigned int & ncount) {
for(const Particle & p: mother.children()) {
if(p.abspid()==411)
d.push_back(p);
else if(p.abspid()==211)
pi.push_back(p);
ncount +=1;
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::abspid==425)) {
const double xp = 2.*p.p3().mod()/sqrtS();
_h_D2_x->fill(xp);
// decay products
Particles d,pi;
unsigned int ncount=0;
findDecayProducts(p,d,pi,ncount);
if(ncount!=2 || d.size()!=1 || pi.size()!=1) continue;
if(d[0].pid()/p.pid()<0) continue;
LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
Vector3 axis = boost.transform(pi[0].momentum()).p3().unit();
double cosL = axis.dot(p.momentum().p3().unit());
// decay angles
_h_D2_ctheta->fill(cosL);
_h_rate->fill(10.);
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_D2_x);
normalize(_h_D2_ctheta);
// br of D mode used from PDG2018
static const double br=0.0898;
scale(_h_rate,br/sumOfWeights()*crossSection()/picobarn);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_D2_x,_h_D2_ctheta,_h_rate;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ARGUS_1989_I268577);
}
|