Rivet analyses

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief B- -> Lambdac+ pbar pi-
  class BABAR_2008_I791879 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2008_I791879);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == PID::BPLUS);
      declare(ufs, "UFS");
      DecayedParticles BP(ufs);
      BP.addStable(4122);
      BP.addStable(-4122);
      declare(BP, "BP");
      // histos
      book(_h[0], "TMP/hA", refData(1, 1, 1));
      book(_h[1], 2, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{-4122, 1}, {2212, 1}, {211, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{4122, 1}, {-2212, 1}, {-211, 1}};
      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
      for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
        // select right decay mode
        int sign = 1;
        if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 3, mode))
          sign = 1;
        else if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 3, modeCC))
          sign = -1;
        else
          continue;
        const Particle& lam = BP.decayProducts()[ix].at(-4122 * sign)[0];
        const Particle& pp = BP.decayProducts()[ix].at(2212 * sign)[0];
        const Particle& pip = BP.decayProducts()[ix].at(211 * sign)[0];
        _h[0]->fill((lam.momentum() + pp.momentum()).mass());
        if (BP.decaying()[ix].children().size() == 2
            && (BP.decaying()[ix].children()[0].abspid() == 4112
                || BP.decaying()[ix].children()[1].abspid() == 4112)) {
          LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(
              BP.decaying()[ix].momentum().betaVec());
          FourMomentum pSigma = boost1.transform(lam.momentum() + pip.momentum());
          Vector3 axis = -pSigma.p3().unit();
          FourMomentum pLambda = boost1.transform(lam.momentum());
          LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pSigma.betaVec());
          _h[1]->fill(axis.dot(boost2.transform(pLambda).p3().unit()));
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // phase space volumes in the different bins (PR has python program which computed these)
      vector<double> phsp = {
          0.1351399774095767,  0.24107906667337267, 0.3088204600383566,  0.36206863378662535,
          0.40659958403332336, 0.4450070368053994,  0.47872719863744506, 0.5086545750109557,
          0.5353906093802568,  0.5593621540798246,  0.5808845790744056,  0.6001982286826937,
          0.6174908272498764,  0.6329119405055217,  0.6465826880700479,  0.6586024850910634,
          0.6690538534165392,  0.67800593732165,    0.685517125504117,   0.6916370414215524,
          0.6964080775759626,  0.6998665941923083,  0.7020438666137178,  0.7029668415116569,
          0.7026587454114315,  0.701139577428797,   0.6984265098419529,  0.6945342141075089,
          0.6894751254590167,  0.6832596558172149,  0.6758963620528058,  0.6673920744258324,
          0.657751988084915,   0.6469797186756903,  0.6350773212151493,  0.6220452692510539,
          0.6078823887065968,  0.5925857373802724,  0.5761504163391165,  0.5585692926468113};
      // normalize the histograms
      for (unsigned int ix = 0; ix < 2; ++ix) normalize(_h[ix], 1., false);
      // convert first plot to scatter and normalize to phase space volume in bin
      // convert to scatter
      Estimate1DPtr tmp;
      book(tmp, 1, 1, 1);
      barchart(_h[0], tmp);
      double step = 0.0344;
      // divide by phase space volume
      for (unsigned int ip = 0; ip < tmp->numBins(); ++ip) tmp->bin(ip + 1).scale(1. / phsp[ip] / step);
    }
    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2008_I791879);

}