Rivet analyses

Dalitz plot analysis of D_s⁺ and D⁺ → π⁺π⁺π⁻

Experiment: FOCUS (Fermilab)

Inspire ID: 635446

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 585 (2004) 200-212

Beams: * *

Beam energies: ANY

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

Measurement of the mass distributions in the decays D_s⁺ and D⁺ → π⁺π⁺π⁻. The data were read from the plots in the paper and the backgrounds subtracted. 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:`FOCUS_2003_I635446.cc`

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

namespace Rivet {


  /// @brief D_s+/D+ -> pi+pi+pi-
  class FOCUS_2003_I635446 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2003_I635446);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411 or Cuts::abspid == 431);
      declare(ufs, "UFS");
      DecayedParticles DD(ufs);
      DD.addStable(PID::PI0);
      DD.addStable(PID::K0S);
      declare(DD, "DD");
      // histos
      book(_h_pippim[0], 1, 1, 1);
      book(_h_pippim[1], 1, 1, 2);
      book(_h_pippim[2], 2, 1, 1);
      book(_h_pippim[3], 2, 1, 2);
      book(_dalitz[0], "dalitz1", 50, 0., 2.0, 50, 0.0, 3.5);
      book(_dalitz[1], "dalitz2", 50, 0., 1.8, 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 DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
        int sign = 1;
        if (DD.decaying()[ix].pid() > 0 && DD.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (DD.decaying()[ix].pid() < 0 && DD.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particles& pip = DD.decayProducts()[ix].at(sign * 211);
        const Particle& pim = DD.decayProducts()[ix].at(-sign * 211)[0];
        double m1 = (pim.momentum() + pip[0].momentum()).mass2();
        double m2 = (pim.momentum() + pip[1].momentum()).mass2();
        if (m1 > m2) swap(m1, m2);
        if (DD.decaying()[ix].abspid() == 431) {
          _dalitz[0]->fill(m1, m2);
          _h_pippim[0]->fill(m1);
          _h_pippim[1]->fill(m2);
        }
        else {
          _dalitz[1]->fill(m1, m2);
          _h_pippim[2]->fill(m1);
          _h_pippim[3]->fill(m2);
        }
      }
    }


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

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pippim[4];
    Histo2DPtr _dalitz[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(FOCUS_2003_I635446);

}

Rivet analyses

Dalitz plot analysis of Ds+ and D+ → π+π+π−

Source code:FOCUS_2003_I635446.cc

Dalitz plot analysis of D_s⁺ and D⁺ → π⁺π⁺π⁻

Source code:`FOCUS_2003_I635446.cc`