Rivet analyses

title: BELLE_2022_I2131772

Mass distributions in $B^+\to\pi^+\pi^0\pi^0$

Experiment: BELLE (KEKB)

Inspire ID: 2131772

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2208.01855

Beams: * *

Beam energies: ANY

Run details: - Any process producing B+ mesons, originally Upsilon(4S) decays

Measurement of the $\pi^+\pi^0$ and $\pi^0\pi^0$ mass distributions in $B^+\to\pi^+\pi^0\pi^0$. The background subtracted, corrected data was read from the plots in the paper

Source code:BELLE_2022_I2131772.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B+ -> pi+ pi0 pi0 class BELLE_2022_I2131772 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2022_I2131772);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
  declare(ufs, "UFS");
  DecayedParticles BP(ufs);
  BP.addStable(111);
  declare(BP, "BP");
  // histos
  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 BP = apply<DecayedParticles>(event, "BP");
  for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
    int sign = 1;
    if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 3, mode))
      sign = 1;
    else if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 3, modeCC))
      sign = -1;
    else
      continue;
    const Particle& pip = BP.decayProducts()[ix].at(sign * 211)[0];
    const Particles& pi0 = BP.decayProducts()[ix].at(111);
    double mpip[2] = {(pip.mom() + pi0[0].mom()).mass(), (pip.mom() + pi0[1].mom()).mass()};
    _h[0]->fill(min(mpip[0], mpip[1]));
    _h[1]->fill((pi0[0].mom() + pi0[1].mom()).mass());
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h, 1.0, false);
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(BELLE_2022_I2131772);

} ```