Rivet analyses

title: CLEOC_2008_I784516

Pion mass distribution in $\psi(2S)\to\pi\pi J/\psi$

Experiment: CLEOC (CESR)

Inspire ID: 784516

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 78 (2008) 011102

Beams: * *

Beam energies: ANY

Run details: - Any process producing psi(2S)

Measurement of the mass distribution in $\psi(2S)\to\pi^+\pi^-J/\psi$ and $\pi^0\pi^0J/\psi$ decays by CLEO. THe data were read from the plots in the paper and may not be corrected for efficiency/acceptance.

Source code:CLEOC_2008_I784516.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief psi(2S) -> J/Psi pi pi class CLEOC_2008_I784516 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2008_I784516);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::pid == 100443);
  declare(ufs, "UFS");
  DecayedParticles psi(ufs);
  psi.addStable(PID::PI0);
  psi.addStable(PID::JPSI);
  declare(psi, "psi");
  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) {
  static const map<PdgId, unsigned int>& mode1 = {{211, 1}, {-211, 1}, {443, 1}};
  static const map<PdgId, unsigned int>& mode2 = {{111, 2}, {443, 1}};
  DecayedParticles psi = apply<DecayedParticles>(event, "psi");
  // loop over particles
  for (unsigned int ix = 0; ix < psi.decaying().size(); ++ix) {
    if (psi.modeMatches(ix, 3, mode1)) {
      const Particle& pip = psi.decayProducts()[ix].at(211)[0];
      const Particle& pim = psi.decayProducts()[ix].at(-211)[0];
      _h[0]->fill((pip.momentum() + pim.momentum()).mass());
    }
    else if (psi.modeMatches(ix, 3, mode2)) {
      const Particles& pi0 = psi.decayProducts()[ix].at(111);
      _h[1]->fill((pi0[0].momentum() + pi0[1].momentum()).mass());
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2];
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOC_2008_I784516);

} ```