Rivet analyses

Mass distributions in the decays Ξc+ → Σ+K−π+ and Ξc+ → Ξ−π+π+

Experiment: FOCUS (Fermilab)

Inspire ID: 618864

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 571 (2003) 139-147

Beams: * *

Beam energies: ANY

Run details: - Any process producing Xic+ mesons

Measurement of the mass distributions in the decays Ξc+ → Σ+K−π+ and Ξc+ → Ξ−π+π+ by FOCUS. The data were read from the plots in the paper.

Source code:FOCUS_2003_I618864.cc

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

namespace Rivet {


  /// @brief Xi_c+ -> Sigma+ K- pi+ and Xi- pi+ pi+
  class FOCUS_2003_I618864 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2003_I618864);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 4232);
      declare(ufs, "UFS");
      DecayedParticles XICP(ufs);
      XICP.addStable(PID::PI0);
      XICP.addStable(PID::K0S);
      XICP.addStable(PID::ETA);
      XICP.addStable(3222);
      XICP.addStable(-3222);
      XICP.addStable(3312);
      XICP.addStable(-3312);
      declare(XICP, "XICP");
      // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) book(_h[ix], 1 + ix, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode1 = {{PID::KMINUS, 1}, {3222, 1}, {PID::PIPLUS, 1}};
      static const map<PdgId, unsigned int>& mode1CC = {{PID::KPLUS, 1}, {-3222, 1}, {PID::PIMINUS, 1}};
      static const map<PdgId, unsigned int>& mode2 = {{3312, 1}, {PID::PIPLUS, 2}};
      static const map<PdgId, unsigned int>& mode2CC = {{-3312, 1}, {PID::PIMINUS, 2}};
      DecayedParticles XICP = apply<DecayedParticles>(event, "XICP");
      // loop over particles
      for (unsigned int ix = 0; ix < XICP.decaying().size(); ++ix) {
        int sign = XICP.decaying()[ix].pid() / XICP.decaying()[ix].abspid();
        if ((sign == 1 && XICP.modeMatches(ix, 3, mode1))
            || (sign == -1 && XICP.modeMatches(ix, 3, mode1CC))) {
          const Particle& pip = XICP.decayProducts()[ix].at(sign * PID::PIPLUS)[0];
          const Particle& Km = XICP.decayProducts()[ix].at(sign * PID::KMINUS)[0];
          for (unsigned int ix = 0; ix < 2; ++ix) _h[0]->fill((pip.momentum() + Km.momentum()).mass());
        }
        else if ((sign == 1 && XICP.modeMatches(ix, 3, mode2))
                 || (sign == -1 && XICP.modeMatches(ix, 3, mode2CC))) {
          const Particles& pip = XICP.decayProducts()[ix].at(sign * PID::PIPLUS);
          const Particle& xi = XICP.decayProducts()[ix].at(sign * 3312)[0];
          _h[1]->fill((pip[0].momentum() + xi.momentum()).mass());
          _h[1]->fill((pip[1].momentum() + xi.momentum()).mass());
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix) normalize(_h[ix], 1., false);
    }

    /// @}


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


  RIVET_DECLARE_PLUGIN(FOCUS_2003_I618864);

}