Rivet analyses

Mass distribution in Ξ_c⁺ → Ξ⁻π⁺π⁺

Experiment: BELLE (KEKB)

Inspire ID: 1698390

Status: VALIDATED

Authors: - Peter Richardson

References: none listed

Beams: * *

Beam energies: ANY

Run details: - Any process producing Xi_c

Measurement of the Ξ⁻π⁺ mass distribution in Ξ_c⁺ → Ξ⁻π⁺π⁺. N.B. data read from figure in paper and background extracted using line on the figure subtracted.

Source code:`BELLE_2018_I1698390.cc`

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

namespace Rivet {


  /// @brief Xi_c -> xi pi pi
  class BELLE_2018_I1698390 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2018_I1698390);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projection
      declare(UnstableParticles(), "UFS");
      // histo
      book(_h, 1, 1, 1);
    }

    void findDecay(int& sign, const Particle& parent, Particles& xi, Particles& pi, unsigned int& nstable) {
      for (const Particle& p : parent.children()) {
        if (p.pid() == sign * 3312) {
          ++nstable;
          xi.push_back(p);
        }
        else if (p.pid() == sign * 211) {
          ++nstable;
          pi.push_back(p);
        }
        else if (p.children().empty())
          ++nstable;
        else
          findDecay(sign, p, xi, pi, nstable);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid == 4232)) {
        int sign = p.pid() / p.abspid();
        Particles xi, pi;
        unsigned int nstable(0);
        findDecay(sign, p, xi, pi, nstable);
        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
        if (nstable == 3 && xi.size() == 1 && pi.size() == 2) {
          double p1 = boost.transform(pi[0].momentum()).p3().mod();
          double p2 = boost.transform(pi[1].momentum()).p3().mod();
          double mass = p1 > p2 ? (pi[1].momentum() + xi[0].momentum()).mass()
                                : (pi[0].momentum() + xi[0].momentum()).mass();
          _h->fill(mass);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2018_I1698390);

}

Rivet analyses

Mass distribution in Ξc+ → Ξ−π+π+

Source code:BELLE_2018_I1698390.cc

Mass distribution in Ξ_c⁺ → Ξ⁻π⁺π⁺

Source code:`BELLE_2018_I1698390.cc`