Rivet analyses

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

namespace Rivet {


  /// @brief Xi_b- 7,8 and 13 TeV
  class LHCB_2019_I1716259 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2019_I1716259);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(), "UFS");
      // CMS energy
      for (double eVal : allowedEnergies()) {
        const string en = toString(round(eVal));
        if (isCompatibleWithSqrtS(eVal)) {
          _sqs = (en == "13000"s) ? "13"s : "7 & 8"s;
        }
      }
      raiseBeamErrorIf(_sqs.empty());

      // histograms
      for (const string& en : vector<string>{"7 & 8"s, "13"s}) {
        for (size_t ix = 0; ix < 2; ++ix) {
          book(_c[en + "xi" + toString(ix)], "TMP/c_xi_" + toString(ix + 1) + "_" + en);
          book(_c[en + "lam" + toString(ix)], "TMP/c_lam_" + toString(ix + 1) + "_" + en);
        }
      }
      const auto& ref = refData<YODA::BinnedEstimate<string>>(1, 1, 1);
      book(_h_xi, "TMP/h_xi", ref);
      book(_h_lam, "TMP/h_lam", ref);
    }

    void findDecayProducts(const Particle& mother,
                           double sign,
                           Particles& Lambda,
                           Particles& Xi,
                           Particles& Jpsi,
                           unsigned int& nstable) const {
      for (const Particle& p : mother.children()) {
        if (p.pid() == 3122 * sign)
          Lambda += p;
        else if (p.pid() == 3312 * sign)
          Xi += p;
        else if (p.pid() == 443)
          Jpsi += p;
        else if (p.pid() == 111 || p.children().empty())
          ++nstable;
        else
          findDecayProducts(p, sign, Lambda, Xi, Jpsi, nstable);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::abspid == 5122 || Cuts::abspid == 5132)) {
        // decay modes
        Particles Lambda, Xi, Jpsi;
        unsigned int nstable = 0;
        double sign = p.pid() > 0 ? 1. : -1.;
        findDecayProducts(p, sign, Lambda, Xi, Jpsi, nstable);
        if (p.abspid() == 5112) {
          _c[_sqs + "lam1"s]->fill();
          if (Lambda.size() == 1 && Jpsi.size() == 1 && nstable == 0) _c[_sqs + "lam0"s]->fill();
        }
        else {
          _c[_sqs + "xi1"]->fill();
          if (Xi.size() == 1 && Jpsi.size() == 1 && nstable == 0) _c[_sqs + "xi0"]->fill();
        }
        // pT and rapidity cuts
        if (p.pT() > 20 * GeV) continue;
        const double eta = p.abseta();
        if (eta < 2. || eta > 6.) continue;
        if (p.abspid() == 5122) {
          _h_lam->fill(_sqs);
        }
        else {
          _h_xi->fill(_sqs);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // first the simple ratio
      BinnedEstimatePtr<string> tmp;
      book(tmp, 2, 1, 1);
      divide(_h_xi, _h_lam, tmp);
      // and the one with brs included
      book(tmp, 1, 1, 1);
      for (const auto& b : tmp->bins()) {
        const string edge = b.xEdge();
        if (_c[edge + "xi1"]->sumW() > 0) {
          _h_xi->bin(b.index()).scaleW(dbl(*_c[edge + "xi0"] / *_c[edge + "xi1"]));
        }
        if (_c[edge + "lam1"]->sumW() > 0) {
          _h_lam->bin(b.index()).scaleW(dbl(*_c[edge + "lam0"] / *_c[edge + "lam1"]));
        }
      }
      divide(_h_xi, _h_lam, tmp);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _h_xi, _h_lam;
    map<string, CounterPtr> _c;
    string _sqs = "";
    /// @}
  };


  RIVET_DECLARE_PLUGIN(LHCB_2019_I1716259);

}