Rivet analyses

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

namespace Rivet {


  /// @brief B -> K l+ l-
  class BELLE_2021_I1748231 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1748231);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 or Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(443);
      BB.addStable(100443);
      BB.addStable(PID::K0S);
      declare(BB, "BB");
      for (unsigned int ix = 0; ix < 4; ++ix)
        for (unsigned int iy = 0; iy < 3; ++iy) {
          book(_h_br[ix][iy], 1, 1 + ix, 1 + iy);
          book(_h_brB[ix][iy], "TMP/h_br_" + toString(ix) + "_" + toString(iy), refData(1, 1 + ix, 1 + iy));
        }
      for (unsigned int ix = 0; ix < 2; ++ix) book(_c[ix], "TMP/nB_" + toString(ix + 1));
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{321, 1}, {13, 1}, {-13, 1}};
      static const map<PdgId, unsigned int>& mode1CC = {{-321, 1}, {13, 1}, {-13, 1}};
      static const map<PdgId, unsigned int>& mode2 = {{310, 1}, {13, 1}, {-13, 1}};
      static const map<PdgId, unsigned int>& mode3 = {{321, 1}, {11, 1}, {-11, 1}};
      static const map<PdgId, unsigned int>& mode3CC = {{-321, 1}, {11, 1}, {-11, 1}};
      static const map<PdgId, unsigned int>& mode4 = {{310, 1}, {11, 1}, {-11, 1}};
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        if (BB.decaying()[ix].abspid() == 521)
          _c[0]->fill();
        else
          _c[1]->fill();
        int imode = 0;
        if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode1))
            || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode1CC)))
          imode = 0;
        else if (BB.modeMatches(ix, 3, mode2))
          imode = 1;
        else if ((BB.decaying()[ix].pid() > 0 && BB.modeMatches(ix, 3, mode3))
                 || (BB.decaying()[ix].pid() < 0 && BB.modeMatches(ix, 3, mode3CC)))
          imode = 2;
        else if (BB.modeMatches(ix, 3, mode4))
          imode = 3;
        else
          continue;
        int il = imode < 2 ? 13 : 11;
        const Particle& lp = BB.decayProducts()[ix].at(-il)[0];
        const Particle& lm = BB.decayProducts()[ix].at(il)[0];
        double qq = (lp.momentum() + lm.momentum()).mass2();
        for (unsigned int iy = 0; iy < 3; ++iy) {
          _h_br[imode][iy]->fill(qq);
          _h_brB[imode][iy]->fill(qq);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // ratio of lifetimes
      double rLife = 1.078;
      // normalize BR plots
      for (unsigned int ix = 0; ix < 4; ++ix) {
        for (unsigned int iy = 0; iy < 3; ++iy) {
          if (ix % 2 == 0) {
            scale(_h_br[ix][iy], 1e7 / *_c[0]);
            scale(_h_brB[ix][iy], 1e7 / *_c[0]);
          }
          else {
            scale(_h_br[ix][iy], 1e7 / *_c[1]);
            // KL0 modes 2x needed for isospin stuff
            scale(_h_brB[ix][iy], 2e7 * rLife / *_c[1]);
          }
        }
      }
      // RK and asymmetry plots
      for (unsigned int ix = 0; ix < 3; ++ix) {
        Estimate1DPtr RK;
        book(RK, 3, 1, 1 + ix);
        divide(_h_brB[0][ix], _h_brB[2][ix], RK);
        book(RK, 3, 2, 1 + ix);
        divide(_h_brB[1][ix], _h_brB[3][ix], RK);
        book(RK, 3, 3, 1 + ix);
        for (size_t ibin = 1; ibin < _h_brB[1][ix]->numBins() + 1; ++ibin) {
          double num = _h_brB[0][ix]->bin(ibin).sumW() + _h_brB[1][ix]->bin(ibin).sumW();
          double numErr2 = _h_brB[0][ix]->bin(ibin).sumW2() + _h_brB[1][ix]->bin(ibin).sumW2();
          double den = _h_brB[2][ix]->bin(ibin).sumW() + _h_brB[3][ix]->bin(ibin).sumW();
          double denErr2 = _h_brB[2][ix]->bin(ibin).sumW2() + _h_brB[3][ix]->bin(ibin).sumW2();
          double val(0.), err(0.);
          if (num > 0. && den > 0.) {
            val = num / den;
            err = val * (numErr2 / sqr(num) + denErr2 / sqr(den));
          }
          RK->bin(ibin).set(val, err);
        }
        book(RK, 2, 1, 1 + ix);
        asymm(_h_brB[1][ix], _h_brB[0][ix], RK);
        book(RK, 2, 2, 1 + ix);
        asymm(_h_brB[3][ix], _h_brB[2][ix], RK);
        // average plot
        book(RK, 2, 3, 1 + ix);
        for (unsigned int ibin = 1; ibin < _h_brB[1][ix]->numBins() + 1; ++ibin) {
          double term0 = _h_brB[1][ix]->bin(ibin).sumW() + _h_brB[3][ix]->bin(ibin).sumW();
          double term0Err2 = _h_brB[1][ix]->bin(ibin).sumW2() + _h_brB[3][ix]->bin(ibin).sumW2();
          double term1 = _h_brB[0][ix]->bin(ibin).sumW() + _h_brB[2][ix]->bin(ibin).sumW();
          double term1Err2 = _h_brB[0][ix]->bin(ibin).sumW2() + _h_brB[2][ix]->bin(ibin).sumW2();
          double val(0.), err(0.);
          if (term0 > 0. && term1 > 0.) {
            val = (term0 - term1) / (term0 + term1);
            err = 4. * (sqr(term1) * term0Err2 + sqr(term0) * term1Err2) / pow(term0 + term1, 4);
          }
          RK->bin(ibin).set(val, err);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _c[2];
    Histo1DPtr _h_br[4][3], _h_brB[4][3];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2021_I1748231);

}