1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/UnstableParticles.hh"
  4#include "Rivet/Projections/DecayedParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief B -> omega pi/K
 10  class BELLE_2006_I735859 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2006_I735859);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // Initialise and register projections
 23      UnstableParticles ufs = UnstableParticles(Cuts::abspid==511 || Cuts::abspid==521);
 24      declare(ufs, "UFS");
 25      DecayedParticles BB(ufs);
 26      BB.addStable(310);
 27      BB.addStable(223);
 28      declare(BB, "BB");
 29      // histos
 30      for (unsigned int ix=0; ix<3; ++ix) {
 31        book(_h[ix], 1, 1, 1+ix);
 32      }
 33    }
 34
 35    void findChildren(const Particle& p, Particles& pim, Particles& pip,
 36                      Particles& pi0, unsigned int &ncount) {
 37      for (const Particle &child : p.children()) {
 38        if (child.pid()==PID::PIPLUS) {
 39          pip.push_back(child);
 40          ncount+=1;
 41        }
 42        else if (child.pid()==PID::PIMINUS) {
 43          pim.push_back(child);
 44          ncount+=1;
 45        }
 46        else if (child.pid()==PID::PI0) {
 47          pi0.push_back(child);
 48          ncount+=1;
 49        }
 50        else if (child.children().empty()) {
 51          ncount+=1;
 52        }
 53        else {
 54          findChildren(child,pim,pip,pi0,ncount);
 55        }
 56      }
 57    }
 58
 59    /// Perform the per-event analysis
 60    void analyze(const Event& event) {
 61      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
 62      // loop over particles
 63      for (unsigned int ix=0; ix<BB.decaying().size(); ++ix) {
 64        unsigned int imode=0;
 65        if (BB.modeMatches(ix,2,mode1) || BB.modeMatches(ix,2,mode1CC)) {
 66          imode=0;
 67        }
 68        else if (BB.modeMatches(ix,2,mode2) || BB.modeMatches(ix,2,mode2CC)) {
 69          imode=1;
 70        }
 71        else if (BB.modeMatches(ix,2,mode3) || BB.modeMatches(ix,2,mode3CC)) {
 72          imode=2;
 73        }
 74        else {
 75          continue;
 76        }
 77        const Particle& omega = BB.decayProducts()[ix].at(223)[0];
 78        // children of the omega
 79        unsigned int ncount=0;
 80        Particles pip,pim,pi0;
 81        findChildren(omega,pim,pip,pi0,ncount);
 82        if (ncount!=3 || !(pim.size()==1 && pip.size()==1 && pi0.size()==1)) continue;
 83        LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(BB.decaying()[ix].mom().betaVec());
 84        FourMomentum pomega = boost1.transform(omega.mom());
 85        FourMomentum pPip   = boost1.transform(pip[0].mom());
 86        FourMomentum pPim   = boost1.transform(pim[0].mom());
 87        // boost to omega frame
 88        LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pomega.betaVec());
 89        pPip   = boost3.transform(pPip);
 90        pPim   = boost3.transform(pPim);
 91        Vector3 axisOmega = pPip.p3().cross(pPim.p3()).unit();
 92        // helicity angle
 93        _h[imode]->fill(abs(pomega.p3().unit().dot(axisOmega)));
 94      }
 95    }
 96
 97
 98    /// Normalise histograms etc., after the run
 99    void finalize() {
100      normalize(_h, 1.0, false);
101    }
102
103    /// @}
104
105
106    /// @name Histograms
107    /// @{
108    Histo1DPtr _h[3];
109    const map<PdgId,unsigned int> mode1   = { { 223,1}, { 321,1}};
110    const map<PdgId,unsigned int> mode1CC = { { 223,1}, {-321,1}};
111    const map<PdgId,unsigned int> mode2   = { { 223,1}, { 211,1}};
112    const map<PdgId,unsigned int> mode2CC = { { 223,1}, {-211,1}};
113    const map<PdgId,unsigned int> mode3   = { { 223,1}, { 130,1}};
114    const map<PdgId,unsigned int> mode3CC = { { 223,1}, { 310,1}};
115    /// @}
116
117
118  };
119
120
121  RIVET_DECLARE_PLUGIN(BELLE_2006_I735859);
122
123}