Rivet analyses

Dalitz plot analysis of D⁺ → π⁺π⁺π⁻

Experiment: E791 (Fermilab)

Inspire ID: 530320

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 86 (2001) 770-774

Beams: * *

Beam energies: ANY

Run details: - Any process producing D+ -> pi+ pi+ pi-

Measurement of the mass distributions in the decay D⁺ → π⁺π⁺π⁻. The data were read from the plots in the paper. Resolution/acceptance effects have been not unfolded and given the agreement with the model in the paper this analysis should only be used for qualitative studies.

Source code:`E791_2001_I530320.cc`

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

namespace Rivet {


  /// @brief  D+ -> pi+pi+pi-
  class E791_2001_I530320 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(E791_2001_I530320);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411);
      declare(ufs, "UFS");
      DecayedParticles DP(ufs);
      DP.addStable(PID::PI0);
      DP.addStable(PID::K0S);
      declare(DP, "DP");
      // histos
      book(_h_pi, 1, 1, 1);
      book(_dalitz, "dalitz", 50, 0., 3.1, 50, 0.0, 3.1);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{211, 2}, {-211, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{-211, 2}, {211, 1}};
      DecayedParticles DP = apply<DecayedParticles>(event, "DP");
      // loop over particles
      for (unsigned int ix = 0; ix < DP.decaying().size(); ++ix) {
        int sign = 1;
        if (DP.decaying()[ix].pid() > 0 && DP.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (DP.decaying()[ix].pid() < 0 && DP.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particles& pip = DP.decayProducts()[ix].at(sign * 211);
        const Particle& pim = DP.decayProducts()[ix].at(-sign * 211)[0];
        double m1 = (pim.momentum() + pip[0].momentum()).mass2();
        double m2 = (pim.momentum() + pip[1].momentum()).mass2();
        _h_pi->fill(m1);
        _h_pi->fill(m2);
        _dalitz->fill(m1, m2);
        _dalitz->fill(m2, m1);
      }
    }


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

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pi;
    Histo2DPtr _dalitz;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(E791_2001_I530320);

}

Rivet analyses

Dalitz plot analysis of D+ → π+π+π−

Source code:E791_2001_I530320.cc

Dalitz plot analysis of D⁺ → π⁺π⁺π⁻

Source code:`E791_2001_I530320.cc`