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Rivet analyses reference
BESIII_2017_I1519425
Differential Decay rates for $D^+\to \{\bar{K}^0,\pi^0\} e^+\nu_e$ from BES
Experiment: BESIII (BEPC II)
Inspire ID: 1519425
Status: VALIDATED
Authors:
References:
- Phys.Rev. D96 (2017) no.1, 012002
Beams: * *
Beam energies: ANY
Run details:
- Events with D-decays, either particle guns or collisions.
Differential decay rates for semileptonic $D^+\to \bar{K}^0,\pi^0e^+\nu_e$ decays
Source code:
BESIII_2017_I1519425.cc
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98 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Add a short analysis description here
class BESIII_2017_I1519425 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1519425);
/// @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_K , 1, 1, 1);
book(_h_q2_pi, 2, 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::abspid==PID::DPLUS)) {
if (isSemileptonicDecay(p, {PID::PI0, PID::POSITRON, PID::NU_E}) ||
isSemileptonicDecay(p, {PID::PI0, PID::ELECTRON, PID::NU_EBAR})) {
_h_q2_pi->fill(q2(p, PID::PI0));
}
else if(isSemileptonicDecay(p, {-311, PID::POSITRON, PID::NU_E})) {
_h_q2_K ->fill(q2(p, -311));
}
else if(isSemileptonicDecay(p, { 311, PID::ELECTRON, PID::NU_EBAR})) {
_h_q2_K ->fill(q2(p, 311));
}
else if(isSemileptonicDecay(p, {PID::K0S, PID::POSITRON, PID::NU_E}) ||
isSemileptonicDecay(p, {PID::K0S, PID::ELECTRON, PID::NU_EBAR})) {
_h_q2_K ->fill(q2(p, PID::K0S));
}
else if(isSemileptonicDecay(p, {PID::K0L, PID::POSITRON, PID::NU_E}) ||
isSemileptonicDecay(p, {PID::K0L, PID::ELECTRON, PID::NU_EBAR})) {
_h_q2_K ->fill(q2(p, PID::K0L));
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// normalize to unity
normalize(_h_q2_K );
normalize(_h_q2_pi);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_q2_K,_h_q2_pi;
//@}
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(BESIII_2017_I1519425);
}
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