Rivet analyses

title: BESIII_2024_I2824162

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

Experiment: BESIII (BEPC)

Inspire ID: 2824162

Status: VALIDATED NOHEPDAT

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 9, 092006 - arXiv: 2409.01419

Beams: * *

Beam energies: ANY

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

Measurement of the mass distributions in $D^+\to K^0_SK^0_S\pi^+\pi^0$ decays by the BESIII collaboration. The data were read from the plots in the paper, and then the backgrounds given subtracted. Resolution and efficiencies have not been unfolded.

Source code:BESIII_2024_I2824162.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class BESIII_2024_I2824162 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2824162);


/// @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 < 2; ++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, 3, mode) && !DD.modeMatches(ix, 3, modeCC)) continue;
    const Particles& K0S = DD.decayProducts()[ix].at(PID::K0S);
    const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
    _h[0]->fill((K0S[0].mom() + K0S[1].mom()).mass2());
    _h[1]->fill((K0S[0].mom() + pip.mom()).mass2());
    _h[1]->fill((K0S[1].mom() + pip.mom()).mass2());
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2];
const map<PdgId, unsigned int> mode = {{PID::K0S, 2}, {211, 1}};
const map<PdgId, unsigned int> modeCC = {{PID::K0S, 2}, {-211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(BESIII_2024_I2824162);

} ```