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114 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief B -> Xs gamma
class BELLE_2009_I825222 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2009_I825222);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(Cuts::abspid==521 || Cuts::abspid==511), "UFS");
// Book histograms
book(_h_br, 1, 1, 1);
book(_p_E, 1, 1, 2);
book(_p_E2,"TMP/E2",refData(1,1,3));
book(_nBottom, "TMP/BottomCounter");
}
void findDecayProducts(const Particle& mother,
unsigned int& nK0, unsigned int& nKp,
unsigned int& nKm) {
for (const Particle & p : mother.children()) {
int id = p.pid();
if ( id == PID::KPLUS ) ++nKp;
else if (id == PID::KMINUS ) ++nKm;
else if (id == PID::K0S) ++nK0;
else if (id == PID::PI0 || id == PID::PIPLUS || id == PID::PIMINUS) {
continue;
}
else if ( !p.children().empty() ) {
findDecayProducts(p, nK0, nKp, nKm);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// Loop over bottoms
for (const Particle& bottom : apply<UnstableParticles>(event, "UFS").particles()) {
// remove mixing entries etc
if(bottom.children()[0].abspid()==bottom.abspid()) continue;
_nBottom->fill();
FourMomentum pgamma(0.,0.,0.,0.);
unsigned int ngamma = 0;
for (const Particle & child : bottom.children()) {
if (child.pid() == PID::PHOTON) {
ngamma += 1;
pgamma += child.momentum();
}
}
if (ngamma != 1) continue;
unsigned int nK0(0),nKp(0),nKm(0);
FourMomentum p_tot(0,0,0,0);
findDecayProducts(bottom, nK0, nKp, nKm);
unsigned int nk = nKp-nKm+nK0;
if (nk % 2 == 1) {
const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(bottom.momentum().betaVec());
double eGamma = boost.transform(pgamma).E();
for(auto bin : _h_br->bins()) {
if(eGamma>bin.xMin()) {
_h_br->fill(bin.xMid());
_p_E ->fill(bin.xMid(),eGamma);
_p_E2->fill(bin.xMid(),sqr(eGamma));
}
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// 1e4 for br ormalization and 0.1 for bin width
scale(_h_br, 1e3/_nBottom->sumW());
// dispersion
Scatter2DPtr dispersion;
book(dispersion,1,1,3);
for(unsigned int ix=0;ix<_p_E2->numBins();++ix) {
double val = _p_E2->bins()[ix].mean()-sqr(_p_E->bins()[ix].mean());
double err = val*sqrt(sqr(_p_E2->bins()[ix].stdErr()/_p_E2->bins()[ix].mean())+
4.*sqr(_p_E->bins()[ix].stdErr()/_p_E->bins()[ix].mean()));
double dx = 0.5*_p_E2->bins()[ix].xWidth();
dispersion->addPoint(_p_E2->bins()[ix].xMid(),val,make_pair(dx,dx),make_pair(err,err));
}
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_br;
Profile1DPtr _p_E,_p_E2;
CounterPtr _nBottom;
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2009_I825222);
}
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