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121 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D+ -> K- pi+ e+ nu_e
class BABAR_2010_I879997 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2010_I879997);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid==411);
declare(ufs, "UFS");
DecayedParticles DP(ufs);
DP.addStable(PID::PI0);
DP.addStable(PID::K0S);
DP.addStable(PID::ETA);
DP.addStable(PID::ETAPRIME);
declare(DP, "DP");
// Book histograms
for(unsigned int ix=0;ix<5;++ix)
book(_h[ix],1,1,1+ix);
double bins[5] = {0.,0.8,0.9,1.,1.6};
for(unsigned int ix=0;ix<4;++ix) {
for(unsigned int iy=0;iy<4;++iy) {
Histo1DPtr tmp;
book(tmp,2+iy,1,1+ix);
_b[ix].add(bins[iy],bins[iy+1],tmp);
}
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { -321,1}, { 211,1}, {-11,1}, { 12,1}};
DecayedParticles DP = apply<DecayedParticles>(event, "DP");
// loop over particles
for(unsigned int ix=0;ix<DP.decaying().size();++ix) {
if ( !DP.modeMatches(ix,4,mode) ) continue;
const Particle & Km = DP.decayProducts()[ix].at(-321)[0];
const Particle & pip= DP.decayProducts()[ix].at( 211)[0];
const Particle & ep = DP.decayProducts()[ix].at( -11)[0];
const Particle & nue= DP.decayProducts()[ix].at( 12)[0];
FourMomentum pKstar = Km.momentum()+pip.momentum();
double mKpi = pKstar.mass();
_h[4]->fill(mKpi);
FourMomentum qq = DP.decaying()[ix].momentum()-pKstar;
double q2 = qq.mass2();
_h[0]->fill(q2);
_b[0].fill(mKpi,q2);
// boost momenta to DP rest frame
LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DP.decaying()[ix].momentum().betaVec());
FourMomentum pKS = boost.transform(pKstar);
Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
boost.preMult(ptoz);
// the momenta in frane to W along z
FourMomentum pD = boost.transform(DP.decaying()[ix].momentum());
FourMomentum pK = boost.transform(Km .momentum());
FourMomentum ppi = boost.transform(pip.momentum());
FourMomentum pe = boost.transform(ep .momentum());
FourMomentum pnu = boost.transform(nue.momentum());
pKstar = pK+ppi;
qq = pD-pKstar;
LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
Vector3 axisK = boostK.transform(pK).p3().unit();
double cosK = axisK.dot(pKstar.p3().unit());
_h[2]->fill(cosK);
_b[2].fill(mKpi,cosK);
LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
Vector3 axisE = boostW.transform(pe).p3().unit();
double cosE = axisE.dot(qq.p3().unit());
_h[3]->fill(cosE);
_b[3].fill(mKpi,cosE);
axisK.setZ(0.);
axisE.setZ(0.);
double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
_h[1]->fill(chi);
_b[1].fill(mKpi,chi);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<5;++ix)
normalize(_h[ix]);
for(unsigned int ix=0;ix<4;++ix)
for (Histo1DPtr hist : _b[ix].histos())
normalize(hist);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[5];
BinnedHistogram _b[4];
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2010_I879997);
}
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