Rivet analyses

Mass distributions in Bc+ decays to charmonia + multihadron final states

Experiment: LHCB (LHC)

Inspire ID: 2138845

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2208.08660

Beams: * *

Beam energies: ANY

Run details: - Any process producing B_c+, originally pp

Mass distributions in Bc+ decays to charmonia + multihadron final states. The data were read from the plots in the paper and may not be corrected for efficiency and acceptance.

Source code:LHCB_2022_I2138845.cc

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

namespace Rivet {


  /// @brief B_c to ccbar + hadrons
  class LHCB_2022_I2138845 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2022_I2138845);


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

    /// Book histograms and initialise projections before the run
    void init() {
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 541);
      declare(ufs, "UFS");
      DecayedParticles BC(ufs);
      BC.addStable(PID::PI0);
      BC.addStable(PID::K0S);
      BC.addStable(PID::JPSI);
      BC.addStable(PID::PSI2S);
      declare(BC, "BC");
      for (unsigned int ix = 0; ix < 3; ++ix) book(_h[ix], 1, 1, 1 + ix);
      for (unsigned int ix = 0; ix < 2; ++ix) {
        book(_h[ix + 3], 2, 1, 1 + ix);
        book(_h[ix + 5], 3, 1, 1 + ix);
        book(_h[ix + 7], 4, 1, 1 + ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{443, 1}, {211, 3}, {-211, 2}};
      static const map<PdgId, unsigned int>& mode1CC = {{443, 1}, {-211, 3}, {211, 2}};
      static const map<PdgId, unsigned int>& mode2 = {{443, 1}, {321, 1}, {-321, 1}, {211, 2}, {-211, 1}};
      static const map<PdgId, unsigned int>& mode2CC = {{443, 1}, {321, 1}, {-321, 1}, {-211, 2}, {211, 1}};
      static const map<PdgId, unsigned int>& mode3 = {{443, 1}, {211, 4}, {-211, 3}};
      static const map<PdgId, unsigned int>& mode3CC = {{443, 1}, {-211, 4}, {211, 3}};
      static const map<PdgId, unsigned int>& mode4 = {{100443, 1}, {211, 2}, {-211, 1}};
      static const map<PdgId, unsigned int>& mode4CC = {{100443, 1}, {-211, 2}, {211, 1}};
      DecayedParticles BC = apply<DecayedParticles>(event, "BC");
      // loop over particles
      for (unsigned int ix = 0; ix < BC.decaying().size(); ++ix) {
        int sign = BC.decaying()[ix].pid() / BC.decaying()[ix].abspid();
        if ((sign == 1 && BC.modeMatches(ix, 6, mode1)) || (sign == -1 && BC.modeMatches(ix, 6, mode1CC))) {
          const Particles& pim = BC.decayProducts()[ix].at(-sign * 211);
          const Particles& pip = BC.decayProducts()[ix].at(sign * 211);
          FourMomentum ptotal = pim[0].momentum() + pim[1].momentum() + pip[0].momentum() + pip[1].momentum()
              + pip[2].momentum();
          _h[0]->fill(ptotal.mass());
          for (unsigned int ix = 0; ix < 3; ++ix)
            for (unsigned int iy = 0; iy < 2; ++iy) {
              FourMomentum prho = pip[ix].momentum() + pim[iy].momentum();
              _h[3]->fill((ptotal - prho).mass());
              _h[5]->fill(prho.mass());
            }
        }
        else if ((sign == 1 && BC.modeMatches(ix, 6, mode2))
                 || (sign == -1 && BC.modeMatches(ix, 6, mode2CC))) {
          const Particles& pim = BC.decayProducts()[ix].at(-sign * 211);
          const Particles& pip = BC.decayProducts()[ix].at(sign * 211);
          const Particle& Kp = BC.decayProducts()[ix].at(sign * 321)[0];
          const Particle& Km = BC.decayProducts()[ix].at(-sign * 321)[0];
          _h[1]->fill(
              (Kp.momentum() + Km.momentum() + pim[0].momentum() + pip[0].momentum() + pip[1].momentum())
                  .mass());
          _h[7]->fill((Kp.momentum() + pim[0].momentum()).mass());
          _h[7]->fill((Km.momentum() + pip[0].momentum()).mass());
          _h[7]->fill((Km.momentum() + pip[1].momentum()).mass());
          _h[8]->fill((Kp.momentum() + Km.momentum()).mass());
        }
        else if ((sign == 1 && BC.modeMatches(ix, 8, mode3))
                 || (sign == -1 && BC.modeMatches(ix, 8, mode3CC))) {
          const Particles& pim = BC.decayProducts()[ix].at(-sign * 211);
          const Particles& pip = BC.decayProducts()[ix].at(sign * 211);
          _h[2]->fill((pim[0].momentum() + pim[1].momentum() + pim[2].momentum() + pip[0].momentum()
                       + pip[1].momentum() + pip[2].momentum() + pip[3].momentum())
                          .mass());
        }
        else if ((sign == 1 && BC.modeMatches(ix, 4, mode4))
                 || (sign == -1 && BC.modeMatches(ix, 4, mode4CC))) {
          const Particles& pim = BC.decayProducts()[ix].at(-sign * 211);
          const Particles& pip = BC.decayProducts()[ix].at(sign * 211);
          _h[4]->fill((pim[0].momentum() + pip[0].momentum() + pip[1].momentum()).mass());
          for (unsigned int iy = 0; iy < 2; ++iy)
            _h[6]->fill((pim[0].momentum() + pip[ix].momentum()).mass());
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 9; ++ix) normalize(_h[ix], 1., false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[9];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(LHCB_2022_I2138845);

}