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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief M_x in B -> eta' Xs
class BELLE_2010_I835104 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I835104);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// projections
declare(UnstableParticles(),"UFS");
// histograms
book(_w_ups4,"/TMP/w_ups4");
book(_h_X,1,1,1);
}
void findDecay(Particle parent, bool & charm, Particles & eta, Particles & pi0,
Particles & pip, Particles & Kp, Particles & K0) {
for(const Particle & p : parent.children()) {
if(isCharm(p)) {
charm = true;
return;
}
else if(p.pid()==PID::ETA) {
eta.push_back(p);
}
else if(p.abspid()==PID::PIPLUS) {
pip.push_back(p);
}
else if(p.abspid()==PID::KPLUS) {
Kp.push_back(p);
}
else if(p.pid()==PID::PI0) {
pi0.push_back(p);
}
else if(p.pid()==PID::K0S) {
K0.push_back(p);
}
else if(!p.children().empty()) {
findDecay(p,charm,eta,pi0,pip,Kp,K0);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
for(const Particle & p : ufs.particles(Cuts::pid==300553)) {
_w_ups4->fill();
const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.mom().betaVec());
for(const Particle & B:p.children()) {
if(B.abspid()!=511 && B.abspid()!=521) continue;
// find the decay
bool charm=false;
Particles eta, pi0, pip, Kp, K0;
findDecay(B,charm,eta,pi0,pip,Kp,K0);
if(charm || eta.size()!=1 ) continue;
if(Kp.empty()&&Kp.empty()) continue;
double pEta = boost.transform(eta[0].momentum()).p3().mod();
if(pEta<2.) continue;
// four momentum of the Xs system
FourMomentum pX;
if(K0.size()==1)
pX+= K0[0].momentum();
else if(Kp.size()==1)
pX+= Kp[0].momentum();
else
continue;
for(const Particle & pi : pip)
pX+=pi.momentum();
if(pi0.size()==1)
pX+=pi0[0].momentum();
_h_X->fill(pX.mass());
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h_X, 0.5/ *_w_ups4);
}
///@}
/// @name Histograms
///@{
CounterPtr _w_ups4;
Histo1DPtr _h_X;
///@}
};
RIVET_DECLARE_PLUGIN(BELLE_2010_I835104);
}
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