Rivet analyses

title: BESIII_2023_I2662580

Mass distributions in $D^+\to K^0_S\pi^+\pi^0\pi^0$ decays

Experiment: BESIII (BEPC)

Inspire ID: 2662580

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2305.15879

Beams: * *

Beam energies: ANY

Run details: - Any process producting D+ mesons, originally psi(3770) decay

Measurement of the mass distributions in $D^+\to K^0_S\pi^+\pi^0\pi^0$ decays by the BESIII collaboration. 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_2023_I2662580.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D+ -> KS0 pi+ pi0 pi0 class BESIII_2023_I2662580 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2662580);


/// @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 DD(ufs);
  DD.addStable(PID::PI0);
  DD.addStable(PID::K0S);
  declare(DD, "DD");
  // histograms
  for (unsigned int ix = 0; ix < 7; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  DecayedParticles DD = apply<DecayedParticles>(event, "DD");
  // loop over particles
  for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
    int sign = DD.decaying()[ix].pid() / DD.decaying()[ix].abspid();
    if (!DD.modeMatches(ix, 4, mode) && !DD.modeMatches(ix, 4, modeCC)) continue;
    const Particle& KS0 = DD.decayProducts()[ix].at(310)[0];
    const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
    const Particles& pi0 = DD.decayProducts()[ix].at(111);
    const double mpipi = (pi0[0].mom() + pi0[1].mom()).mass();
    if (mpipi > 0.46 && mpipi < 0.52) continue;
    _h[3]->fill(mpipi);
    _h[2]->fill((KS0.mom() + pip.mom()).mass());
    _h[5]->fill((KS0.mom() + pi0[0].mom() + pi0[1].mom()).mass());
    _h[6]->fill((pip.mom() + pi0[0].mom() + pi0[1].mom()).mass());
    for (unsigned int ix = 0; ix < 2; ++ix) {
      _h[0]->fill((KS0.mom() + pi0[ix].mom()).mass());
      _h[1]->fill((pip.mom() + pi0[ix].mom()).mass());
      _h[4]->fill((KS0.mom() + pip.mom() + pi0[ix].mom()).mass());
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[7];
const map<PdgId, unsigned int> mode = {{310, 1}, {211, 1}, {111, 2}};
const map<PdgId, unsigned int> modeCC = {{310, 1}, {-211, 1}, {111, 2}};
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2023_I2662580);

} ```