Rivet analyses

title: BESIII_2018_I1693610

Mass distributions in the decays $D^0\to K^-\pi^+\eta^\prime$, $D^0\to K^0_S\pi^0\eta^\prime$, $D^+\to K^0_S\pi^+\eta^\prime$

Experiment: BESIII (BEPC)

Inspire ID: 1693610

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 98 (2018) 9, 092009

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 or D+ mesons

Measurement of the mass distributions in the decays $D^0\to K^-\pi^+\eta^\prime$, $D^0\to K^0_S\pi^0\eta^\prime$, $D^+\to K^0_S\pi^+\eta^\prime$ by BES. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code:BESIII_2018_I1693610.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D -> eta' decays class BESIII_2018_I1693610 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1693610);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411 || Cuts::abspid == 421);
  declare(ufs, "UFS");
  DecayedParticles DD(ufs);
  DD.addStable(PID::PI0);
  DD.addStable(PID::K0S);
  DD.addStable(PID::ETA);
  DD.addStable(PID::ETAPRIME);
  declare(DD, "DD");
  // histograms
  for (unsigned int ix = 0; ix < 9; ++ix) book(_h[ix], 1, 1, 1 + ix);
  for (unsigned int ix = 0; ix < 3; ++ix)
    book(_dalitz[ix], "dalitz_" + toString(ix + 1), 50, 0.4, 0.9, 50, 1.1, 1.9);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // define the decay modes
  static const map<PdgId, unsigned int>& mode1 = {{-321, 1}, {211, 1}, {331, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{321, 1}, {-211, 1}, {331, 1}};
  static const map<PdgId, unsigned int>& mode2 = {{310, 1}, {111, 1}, {331, 1}};
  static const map<PdgId, unsigned int>& mode3 = {{310, 1}, {211, 1}, {331, 1}};
  static const map<PdgId, unsigned int>& mode3CC = {{310, 1}, {-211, 1}, {331, 1}};
  DecayedParticles DD = apply<DecayedParticles>(event, "DD");
  // loop over particles
  for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
    // D0 -> K- pi+ omega
    if ((DD.decaying()[ix].pid() == 421 && DD.modeMatches(ix, 3, mode1))
        || (DD.decaying()[ix].pid() == -421 && DD.modeMatches(ix, 3, mode1CC))) {
      int sign = DD.decaying()[ix].pid() / 421;
      const Particles& pip = DD.decayProducts()[ix].at(sign * 211);
      const Particles& Km = DD.decayProducts()[ix].at(-sign * 321);
      const Particles& etaP = DD.decayProducts()[ix].at(331);
      double mKpi = (pip[0].momentum() + Km[0].momentum()).mass2();
      double mpietaP = (pip[0].momentum() + etaP[0].momentum()).mass2();
      _dalitz[0]->fill(mKpi, mpietaP);
      _h[0]->fill(sqrt(mKpi));
      _h[1]->fill((Km[0].momentum() + etaP[0].momentum()).mass());
      _h[2]->fill(sqrt(mpietaP));
    }
    // D0 -> KS0 pi0 etaP
    else if (DD.decaying()[ix].abspid() == 421 && DD.modeMatches(ix, 3, mode2)) {
      const Particles& pi0 = DD.decayProducts()[ix].at(111);
      const Particles& KS0 = DD.decayProducts()[ix].at(310);
      const Particles& etaP = DD.decayProducts()[ix].at(331);
      double mKpi = (pi0[0].momentum() + KS0[0].momentum()).mass2();
      double mpietaP = (pi0[0].momentum() + etaP[0].momentum()).mass2();
      _dalitz[1]->fill(mKpi, mpietaP);
      _h[3]->fill(sqrt(mKpi));
      _h[4]->fill((KS0[0].momentum() + etaP[0].momentum()).mass());
      _h[5]->fill(sqrt(mpietaP));
    }
    // D0 -> K- pi+ etaP
    else if ((DD.decaying()[ix].pid() == 411 && DD.modeMatches(ix, 3, mode3))
             || (DD.decaying()[ix].pid() == -411 && DD.modeMatches(ix, 3, mode3CC))) {
      int sign = DD.decaying()[ix].pid() / 411;
      const Particles& pip = DD.decayProducts()[ix].at(sign * 211);
      const Particles& KS0 = DD.decayProducts()[ix].at(310);
      const Particles& etaP = DD.decayProducts()[ix].at(331);
      double mKpi = (pip[0].momentum() + KS0[0].momentum()).mass2();
      double mpietaP = (pip[0].momentum() + etaP[0].momentum()).mass2();
      _dalitz[2]->fill(mKpi, mpietaP);
      _h[6]->fill(sqrt(mKpi));
      _h[7]->fill((KS0[0].momentum() + etaP[0].momentum()).mass());
      _h[8]->fill(sqrt(mpietaP));
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 9; ++ix) normalize(_h[ix], 1., false);
  for (unsigned int ix = 0; ix < 3; ++ix) normalize(_dalitz[ix]);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[9];
Histo2DPtr _dalitz[3];
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2018_I1693610);

} ```