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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief q^2 in D+ -> eta e+ nu_e
class BESIII_2018_I1662660 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1662660);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_q2, 1, 1, 1);
}
// Calculate the Q2 using mother and daugher meson
double q2(const Particle& B, int mesonID) {
FourMomentum q = B.mom() - filter_select(B.children(), Cuts::pid==mesonID)[0];
return q*q;
}
// Check for explicit decay into pdgids
bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
// Trivial check to ignore any other decays but the one in question modulo photons
const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
if (children.size()!=ids.size()) return false;
// Check for the explicit decay
return all(ids, [&](int i){return count(children, hasPID(i))==1;});
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Loop over D+ mesons
for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::DPLUS )) {
if(p.pid()==PID::DPLUS && isSemileptonicDecay(p, {PID::ETA, PID::EPLUS, PID::NU_E}) ) {
_h_q2->fill(q2(p, PID::ETA));
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_q2);
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_q2;
///@}
};
RIVET_DECLARE_PLUGIN(BESIII_2018_I1662660);
}
|