// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Electron spectrum in B decays
class CRYSTAL_BALL_1989_I263581 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CRYSTAL_BALL_1989_I263581);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// projections
declare(UnstableParticles(),"UFS");
// Book histograms
// specify custom binning
book(_h_all, 1,1,1);
book(_nB,"/TMP/nB");
}
void findDecayProducts(Particle parent, Particles & em) {
for(const Particle & p : parent.children()) {
if(p.abspid() == PID::EMINUS) {
em.push_back(p);
}
else {
findDecayProducts(p,em);
}
}
}
/// 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();
Particles em;
findDecayProducts(p2,em);
for(const Particle & electron : em) {
double en = cms_boost.transform(electron.momentum()).E();
_h_all->fill(en);
}
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// normalize to number of B decays
scale(_h_all, 1./ *_nB);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_all;
CounterPtr _nB;
/// @}
};
RIVET_DECLARE_PLUGIN(CRYSTAL_BALL_1989_I263581);
}