Rivet analyses

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

namespace Rivet {


  /// @brief B -> c l nu moments
  class BELLE_2023_I2649712 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2023_I2649712);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521), "UFS");
      // histos
      for (unsigned int ix = 0; ix < 4; ++ix) {
        book(_p[ix], 1 + ix, 1, 1);
        book(_p[ix + 4], "TMP/p_" + toString(ix), refData<YODA::BinnedEstimate<string>>(1 + ix, 1, 1));
      }
    }

    void findDecayProducts(Particle parent,
                           Particles& em,
                           Particles& ep,
                           Particles& nue,
                           Particles& nueBar,
                           bool& charm) {
      for (const Particle& p : parent.children()) {
        if (PID::isCharmHadron(p.pid())) {
          charm = true;
        }
        else if (p.pid() == PID::EMINUS || p.pid() == PID::MUON) {
          em.push_back(p);
        }
        else if (p.pid() == PID::EPLUS || p.pid() == PID::ANTIMUON) {
          ep.push_back(p);
        }
        else if (p.pid() == PID::NU_E || p.pid() == PID::NU_MU) {
          nue.push_back(p);
        }
        else if (p.pid() == PID::NU_EBAR || p.pid() == PID::NU_MUBAR) {
          nueBar.push_back(p);
        }
        else if (PID::isBottomHadron(p.pid())) {
          findDecayProducts(p, em, ep, nue, nueBar, charm);
        }
        else if (!PID::isHadron(p.pid())) {
          findDecayProducts(p, em, ep, nue, nueBar, charm);
        }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      if (_edges.empty()) _edges = _p[0]->xEdges();
      // find and loop over Upslion(4S)
      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
        if (p.children().empty() || (p.children().size() == 1 && p.children()[1].abspid() == p.abspid())) {
          continue;
        }
        // find decay products
        bool charm = false;
        Particles em, ep, nue, nueBar;
        findDecayProducts(p, em, ep, nue, nueBar, charm);
        if (!charm) continue;
        FourMomentum pl, pnu;
        if (em.size() == 1 && nueBar.size() == 1 && em[0].pid() + 1 == -nueBar[0].pid()) {
          pl = em[0].mom();
          pnu = nueBar[0].mom();
        }
        else if (ep.size() == 1 && nue.size() == 1 && nue[0].pid() == -ep[0].pid() + 1) {
          pl = ep[0].mom();
          pnu = nue[0].mom();
        }
        else {
          continue;
        }
        double q2 = (pl + pnu).mass2();
        vector<double> q2n(8);
        for (unsigned int ix = 0; ix < 8; ++ix) q2n[ix] = pow(q2, 1 + ix);
        if (q2 < 1.5) continue;
        double q2cut = 1.5;
        for (unsigned int ibin = 0; ibin < 15; ++ibin) {
          if (q2 > q2cut) {
            for (unsigned int ix = 0; ix < 8; ++ix) {
              _p[ix]->fill(_edges[ibin], q2n[ix]);
            }
          }
          else
            break;
          q2cut += 0.5;
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      BinnedEstimatePtr<string> tmp[3];
      for (unsigned int ix = 0; ix < 3; ++ix) book(tmp[ix], 5 + ix, 1, 1);
      for (unsigned int iy = 0; iy < _p[0]->numBins(); ++iy) {
        double q2 = _p[0]->bin(iy + 1).mean(2), q4 = _p[1]->bin(iy + 1).mean(2),
               q6 = _p[2]->bin(iy + 1).mean(2), q8 = _p[3]->bin(iy + 1).mean(2),
               q10 = _p[4]->bin(iy + 1).mean(2), q12 = _p[5]->bin(iy + 1).mean(2),
               q14 = _p[6]->bin(iy + 1).mean(2), q16 = _p[7]->bin(iy + 1).mean(2);
        // q4 case
        double N = _p[0]->bin(iy + 1).effNumEntries();
        double value = q4 - sqr(q2);
        double error = (-sqr(q4) + 4 * sqr(q2) * (-sqr(q2) + 2 * q4) - 4 * q2 * q6 + q8) / N;
        tmp[0]->bin(iy + 1).set(value, sqrt(error));
        // q6 case
        value = q6 + q2 * (2 * sqr(q2) - 3 * q4);
        error = (q12 - sqr(q6) - 6 * q2 * (q10 - 5 * q4 * q6) + 3 * q4 * (3 * sqr(q4) - 2 * q8)
                 + sqr(q2) * (-72 * sqr(q4) + 36 * sqr(q2) * (-sqr(q2) + 3 * q4) - 48 * q2 * q6 + 21 * q8))
            / N;
        tmp[1]->bin(iy + 1).set(value, sqrt(error));
        // q8 case
        value = q8 + q2 * (-3 * q2 * sqr(q2) + 6 * q2 * q4 - 4 * q6);
        error = (q16 - 8 * q6 * (q10 - 2 * q4 * q6) - sqr(q8)
                 - 8 * q2 * (q14 - 3 * q4 * (q10 - 4 * q4 * q6) - 6 * q6 * q8)
                 + 4 * sqr(q2)
                     * (7 * q12 - 28 * sqr(q6) + 6 * q2 * (-3 * q10 + 22 * q4 * q6)
                        + 3 * q4 * (12 * sqr(q4) - 11 * q8)
                        + 3 * sqr(q2)
                            * (-12 * sqr(q2) * (sqr(q2) - 4 * q4) - 51 * sqr(q4) - 28 * q2 * q6 + 13 * q8)))
            / N;
        tmp[2]->bin(iy + 1).set(value, sqrt(error));
      }
    }
    /// @}


    /// @name Histograms
    /// @{
    BinnedProfilePtr<string> _p[8];
    vector<string> _edges;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2023_I2649712);

}