Rivet analyses

title: BELLE_2019_I1729311

$B^0\to p \bar{p}\pi^0$

Experiment: BELLE (KEKB)

Inspire ID: 1729311

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 99 (2019) 9, 091104

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 originally e+e- at Upsilon(4S)

Measurement of the mass distributions in the decay $B^0\to p \bar{p}\pi^0$. The data were read from the plots in the paper, but is corrected for detector efficiency.

Source code:BELLE_2019_I1729311.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B0 -> p pbar pi0 class BELLE_2019_I1729311 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2019_I1729311);


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

/// Book histograms and initialise projections before the run
void init() {
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
  declare(ufs, "UFS");
  DecayedParticles B0(ufs);
  B0.addStable(PID::PI0);
  B0.addStable(PID::K0S);
  B0.addStable(PID::ETA);
  B0.addStable(PID::ETAPRIME);
  declare(B0, "B0");
  book(_h[0], 1, 1, 1);
  for (unsigned int ix = 0; ix < 2; ++ix) book(_h[ix + 1], 2, 1, 1 + ix);
  book(_dalitz, "dalitz", 50, 1., 20., 50, 1., 20.);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode = {{2212, 1}, {-2212, 1}, {111, 1}};
  DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
  // loop over particles
  for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
    if (!B0.modeMatches(ix, 3, mode)) continue;
    int sign = B0.decaying()[ix].pid() / 511;
    const Particle& pi0 = B0.decayProducts()[ix].at(111)[0];
    const Particle& pp = B0.decayProducts()[ix].at(sign * 2212)[0];
    const Particle& pbar = B0.decayProducts()[ix].at(-sign * 2212)[0];
    double mminus = (pbar.momentum() + pi0.momentum()).mass2();
    double mplus = (pp.momentum() + pi0.momentum()).mass2();
    _h[0]->fill((pp.momentum() + pbar.momentum()).mass());
    _h[1]->fill(sqrt(mplus));
    _h[2]->fill(sqrt(mminus));
    _dalitz->fill(mplus, mminus);
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(BELLE_2019_I1729311);

} ```