Rivet analyses

title: CLEOII_2001_I537154

Kinematic distributions in the decay $D^0\to K^-\pi^+\pi^0$

Experiment: CLEOII (CESR)

Inspire ID: 537154

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys. Rev. D78:052001, 2008

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0

Kinematic distributions in the decay $D^0\to K^-\pi^+\pi^0$

Source code:CLEOII_2001_I537154.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D0 -> K- pi+ pi0 class CLEOII_2001_I537154 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2001_I537154);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 421);
  declare(ufs, "UFS");
  DecayedParticles D0(ufs);
  D0.addStable(PID::PI0);
  D0.addStable(PID::K0S);
  D0.addStable(PID::ETA);
  D0.addStable(PID::ETAPRIME);
  declare(D0, "D0");
  // histograms
  book(_h_Kpi0, 1, 1, 1);
  book(_h_Kpip, 1, 2, 1);
  book(_h_pipi, 1, 3, 1);
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const double E0 = 22.1e-5;
  static const double Ex = -6.89e-5;
  static const double Ey = -27.1e-5;
  static const double Ex2 = 10.4e-5;
  static const double Exy = 38.2e-5;
  static const double Ey2 = 12.4e-5;
  static const double Ex3 = -3.00e-5;
  static const double Ex2y = -7.97e-5;
  static const double Exy2 = -12.8e-5;
  static const double Ey3 = -0.53e-5;

  static const map<PdgId, unsigned int>& mode = {{-321, 1}, {211, 1}, {111, 1}};
  static const map<PdgId, unsigned int>& modeCC = {{321, 1}, {-211, 1}, {111, 1}};
  DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
  // loop over particles
  for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
    int sign = 1;
    if (D0.decaying()[ix].pid() > 0 && D0.modeMatches(ix, 3, mode)) {
      sign = 1;
    }
    else if (D0.decaying()[ix].pid() < 0 && D0.modeMatches(ix, 3, modeCC)) {
      sign = -1;
    }
    else
      continue;
    const Particles& pi0 = D0.decayProducts()[ix].at(111);
    const Particles& Km = D0.decayProducts()[ix].at(-sign * 321);
    const Particles& pip = D0.decayProducts()[ix].at(sign * 211);
    double mKpip = (Km[0].momentum() + pip[0].momentum()).mass2();
    double mKpi0 = (Km[0].momentum() + pi0[0].momentum()).mass2();
    double mpipi = (pi0[0].momentum() + pip[0].momentum()).mass2();
    double eff = E0 + Ex * mKpip + Ey * mpipi + Ex2 * sqr(mKpip) + Exy * mKpip * mpipi + Ey2 * sqr(mpipi)
        + Ex3 * pow(mKpip, 3) + Ex2y * sqr(mKpip) * mpipi + Exy2 * mKpip * sqr(mpipi)
        + Ey3 * pow(mpipi, 3);
    _h_Kpi0->fill(mKpi0, eff);
    _h_Kpip->fill(mKpip, eff);
    _h_pipi->fill(mpipi, eff);
  }
}

/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_Kpi0);
  normalize(_h_Kpip);
  normalize(_h_pipi);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_Kpi0, _h_Kpip, _h_pipi;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_2001_I537154);

} ```