// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief D_s+ -> K+K- e+ nu_e
class BABAR_2008_I790461 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2008_I790461);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid==431);
declare(ufs, "UFS");
DecayedParticles DS(ufs);
DS.addStable(PID::PI0);
DS.addStable(PID::K0S);
DS.addStable(PID::ETA);
DS.addStable(PID::ETAPRIME);
declare(DS, "DS");
// Book histograms
book(_h[0],1,1,1);
for(unsigned int ix=0;ix<4;++ix)
book(_h[ix+1],2,1,1+ix);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 321,1}, {-321,1}, {-11,1}, { 12,1}};
DecayedParticles DS = apply<DecayedParticles>(event, "DS");
// loop over particles
for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
if(!DS.modeMatches(ix,4,mode)) continue;
const Particle & Kp = DS.decayProducts()[ix].at( 321)[0];
const Particle & Km = DS.decayProducts()[ix].at(-321)[0];
const Particle & ep = DS.decayProducts()[ix].at( -11)[0];
const Particle & nue= DS.decayProducts()[ix].at( 12)[0];
FourMomentum pPhi = Kp.momentum()+Km.momentum();
_h[0]->fill(pPhi.mass());
FourMomentum qq = DS.decaying()[ix].momentum()-pPhi;
_h[1]->fill(qq.mass2());
// boost momenta to DS rest frame
LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DS.decaying()[ix].momentum().betaVec());
FourMomentum pPHI = boost.transform(pPhi);
Matrix3 ptoz(-pPHI.p3().unit(), Vector3(0,0,1));
boost.preMult(ptoz);
// the momenta in frane to W along z
FourMomentum pD = boost.transform(DS.decaying()[ix].momentum());
FourMomentum pKp = boost.transform(Kp .momentum());
FourMomentum pKm = boost.transform(Km .momentum());
FourMomentum pe = boost.transform(ep .momentum());
FourMomentum pnu = boost.transform(nue.momentum());
pPhi = pKp+pKm;
qq = pD-pPhi;
LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pPhi.betaVec());
Vector3 axisK = boostK.transform(pKp).p3().unit();
_h[3]->fill(axisK.dot(pPhi.p3().unit()));
LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
Vector3 axisE = boostW.transform(pe).p3().unit();
_h[2]->fill(axisE.dot(qq.p3().unit()));
axisK.setZ(0.);
axisE.setZ(0.);
double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
_h[4]->fill(chi);
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<5;++ix)
normalize(_h[ix]);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[5];
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2008_I790461);
}