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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Electron spectrum in B decays
class BABAR_2017_I1498564 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2017_I1498564);
/// @name Analysis methods
//@{
/// Book histograms and initialise projections before the run
void init() {
// projections
declare(UnstableParticles(),"UFS");
// Book histograms
// specify custom binning
book(_h_light, 1,1,1);
book(_h_all , 1,1,2);
book(_nB,"/TMP/nB");
}
void findDecayProducts(Particle parent, Particles & em, Particles & ep,
Particles & nue, Particles & nueBar, bool & charm) {
for(const Particle & p : parent.children()) {
if(PID::isCharmHadron(p.pid())) {
charm=true;
}
else if(p.pid() == PID::EMINUS) {
em.push_back(p);
}
else if(p.pid() == PID::EPLUS) {
ep.push_back(p);
}
else if(p.pid() == PID::NU_E) {
nue.push_back(p);
}
else if(p.pid() == PID::NU_EBAR) {
nueBar.push_back(p);
}
else if(PID::isBottomHadron(p.pid())) {
findDecayProducts(p,em,ep,nue,nueBar,charm);
}
else if(!PID::isHadron(p.pid())) {
findDecayProducts(p,em,ep,nue,nueBar,charm);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// find and loop over Upslion(4S)
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for (const Particle& p : ufs.particles(Cuts::pid==300553)) {
// boost to rest frame
LorentzTransform cms_boost;
if (p.p3().mod() > 1*MeV)
cms_boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
// loop over decay products
for(const Particle & p2 : p.children()) {
if(p2.abspid()==511 || p2.abspid()==521) {
_nB->fill();
bool charm = false;
Particles em,ep,nue,nueBar;
findDecayProducts(p2,em,ep,nue,nueBar,charm);
if(em.size()==1 && nueBar.size()==1) {
double pmod = cms_boost.transform(em[0].momentum()).p3().mod();
_h_all->fill(pmod);
if(!charm) _h_light->fill(pmod);
}
else if(ep.size()==1 && nue.size()==1) {
double pmod = cms_boost.transform(ep[0].momentum()).p3().mod();
_h_all->fill(pmod);
if(!charm) _h_light->fill(pmod);
}
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// normalize to number of B decays
scale(_h_all, 1./ *_nB);
scale(_h_light, 1./ *_nB);
}
//@}
/// @name Histograms
//@{
Histo1DPtr _h_light,_h_all;
CounterPtr _nB;
//@}
};
RIVET_DECLARE_PLUGIN(BABAR_2017_I1498564);
}
|