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107 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief Bbar0 -> J/[psi K- pi+
class BELLE_2014_I1312626 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2014_I1312626);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// projections
UnstableParticles ufs = UnstableParticles(Cuts::abspid==511);
declare(ufs, "UFS");
DecayedParticles B0(ufs);
B0.addStable( 443);
declare(B0, "B0");
// histograms
for(unsigned int ix=0;ix<7;++ix)
book(_h_mass[ix],1,1,1+ix);
for(unsigned int ix=0;ix<2;++ix)
book(_h_angle[ix],2,1,1+ix);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 211,1}, {-321,1}, { 443,1}};
static const map<PdgId,unsigned int> & modeCC = { {-211,1}, { 321,1}, { 443,1}};
DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
for(unsigned int ix=0;ix<B0.decaying().size();++ix) {
int sign=1;
if (B0.decaying()[ix].pid()<0 && B0.modeMatches(ix,3,mode )) sign = 1;
if (B0.decaying()[ix].pid()>0 && B0.modeMatches(ix,3,modeCC)) sign =-1;
else continue;
const Particle & pip = B0.decayProducts()[ix].at( sign*211)[0];
const Particle & Km = B0.decayProducts()[ix].at(-sign*321)[0];
const Particle & JPsi = B0.decayProducts()[ix].at( 443)[0];
double mpiJ2 = (pip.momentum()+JPsi.momentum()).mass2();
double mKpi2 = (pip.momentum()+Km .momentum()).mass2();
if(mpiJ2<16.) _h_mass[0]->fill(mKpi2);
else if(mpiJ2<19.) _h_mass[1]->fill(mKpi2);
else _h_mass[2]->fill(mKpi2);
if(mKpi2<1.2) _h_mass[3]->fill(mpiJ2);
else if(mKpi2<2.05) _h_mass[4]->fill(mpiJ2);
else if(mKpi2<3.2 ) _h_mass[5]->fill(mpiJ2);
else _h_mass[6]->fill(mpiJ2);
// mass cuts for angular variables
if(mKpi2<1.2 || mpiJ2<16. || mpiJ2>19.) continue;
// helicity angle find J.psi leptonic children
if(JPsi.children().size()!=2) continue;
if(JPsi.children()[0].pid()!=-JPsi.children()[1].pid()) continue;
if(JPsi.children()[0].abspid()!=PID::EMINUS &&
JPsi.children()[0].abspid()!=PID::MUON) continue;
Particle lm = JPsi.children()[0];
Particle lp = JPsi.children()[1];
if(lm.pid()<0) swap(lm,lp);
LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(B0.decaying()[ix].momentum().betaVec());
FourMomentum ppsi = boost1.transform(JPsi.momentum());
Vector3 axis1 = -ppsi.p3().unit();
LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(ppsi.betaVec());
FourMomentum plp = boost2.transform(boost1.transform(lp.momentum()));
double cL = plp.p3().unit().dot(axis1);
_h_angle[0]->fill(cL);
Vector3 LTrans = plp.p3() - cL*plp.p3().mod()*axis1;
FourMomentum pKpi = pip.momentum()+Km.momentum();
LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKpi.betaVec());
FourMomentum ppi = boost3.transform(boost1.transform(pip.momentum()));
double cPi = ppi.p3().unit().dot(axis1);
Vector3 PTrans = ppi.p3() - cPi*ppi.p3().mod()*axis1;
double phi = atan2(LTrans.cross(PTrans).dot(axis1), LTrans.dot(PTrans));
_h_angle[1]->fill(phi);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<7;++ix)
normalize(_h_mass[ix],1.,false);
for(unsigned int ix=0;ix<2;++ix)
normalize(_h_angle[ix],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_mass[7],_h_angle[2];
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2014_I1312626);
}
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