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108 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Bs0 -> Ds* Ds*
class BELLE_2013_I1124584 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2013_I1124584);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==531);
declare(ufs, "UFS");
// histograms
for(unsigned int ix=0;ix<2;++ix)
book(_h[ix],1,1,1+ix);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
Particles BS0 = apply<UnstableParticles>(event, "UFS").particles();
for(const Particle & p : BS0) {
if(p.children().size()!=2) continue;
if(p.children()[0].pid()!=-p.children()[1].pid()) continue;
if(p.children()[0].abspid()!=433) continue;
Particle Dp = p.children()[0];
Particle Dm = p.children()[1];
if (p.pid()>0 && Dp.pid()<0) swap(Dp,Dm);
else if(p.pid()<0 && Dp.pid()>0) swap(Dp,Dm);
// boost to rest frame
LorentzTransform boostB = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
FourMomentum pB = boostB.transform(p.momentum());
if(Dp.children().size()==2) {
Particle gamma;
bool found = true;
if(Dp.children()[0].pid()==PID::GAMMA &&
Dp.children()[1].abspid()==431)
gamma = Dp.children()[0];
else if (Dp.children()[1].pid()==PID::GAMMA &&
Dp.children()[0].abspid()==431)
gamma = Dp.children()[1];
else
found = false;
if( found) {
FourMomentum pD = boostB.transform(Dp.momentum());
FourMomentum pgamma = boostB.transform(gamma.momentum());
LorentzTransform boostD = LorentzTransform::mkFrameTransformFromBeta(pD.betaVec());
Vector3 axisB = boostD.transform(pB).p3().unit();
Vector3 axisG = boostD.transform(pgamma).p3().unit();
_h[0]->fill(axisB.dot(axisG));
}
}
if(Dm.children().size()==2) {
Particle gamma;
bool found = true;
if(Dm.children()[0].pid()==PID::GAMMA &&
Dm.children()[1].abspid()==431)
gamma = Dm.children()[0];
else if (Dm.children()[1].pid()==PID::GAMMA &&
Dm.children()[0].abspid()==431)
gamma = Dm.children()[1];
else
found = false;
if( found) {
FourMomentum pD = boostB.transform(Dm.momentum());
FourMomentum pgamma = boostB.transform(gamma.momentum());
LorentzTransform boostD = LorentzTransform::mkFrameTransformFromBeta(pD.betaVec());
Vector3 axisB = boostD.transform(pB).p3().unit();
Vector3 axisG = boostD.transform(pgamma).p3().unit();
_h[1]->fill(axisB.dot(axisG));
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<2;++ix)
normalize(_h[ix],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[2];
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2013_I1124584);
}
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