Rivet analyses

title: BABAR_2011_I897848

Mass distributions in $B^0\to K^+\pi^-\pi^0$ decays

Experiment: BABAR (PEP-II)

Inspire ID: 897848

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 83 (2011) 112010

Beams: * *

Beam energies: ANY

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

Measurements of mass distributions in $B^0\to K^+\pi^-\pi^0$ decays. The data were read from the plots in the paper and the backgrounds given subtracted.

Source code:BABAR_2011_I897848.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B0 -> K+ pi- pi0 class BABAR_2011_I897848 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2011_I897848);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511);
  declare(ufs, "UFS");
  DecayedParticles B0(ufs);
  B0.addStable(PID::PI0);
  declare(B0, "B0");
  // histograms
  for (unsigned int ix = 0; ix < 3; ++ix) {
    for (unsigned int iy = 0; iy < 2; ++iy) {
      book(_h[ix][iy], 1 + ix, 1, 1 + iy);
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode = {{321, 1}, {-211, 1}, {111, 1}};
  static const map<PdgId, unsigned int>& modeCC = {{-321, 1}, {211, 1}, {111, 1}};
  DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
  // loop over particles
  for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
    int sign = 1;
    if (B0.decaying()[ix].pid() > 0 && B0.modeMatches(ix, 3, mode)) {
      sign = 1;
    }
    else if (B0.decaying()[ix].pid() < 0 && B0.modeMatches(ix, 3, modeCC)) {
      sign = -1;
    }
    else
      continue;
    const Particle& Kp = B0.decayProducts()[ix].at(sign * 321)[0];
    const Particle& pim = B0.decayProducts()[ix].at(-sign * 211)[0];
    const Particle& pi0 = B0.decayProducts()[ix].at(111)[0];
    double mpipi = (pim.momentum() + pi0.momentum()).mass();
    _h[0][0]->fill(mpipi);
    if (mpipi < 1.8) _h[0][1]->fill(mpipi);
    double mKpi = (Kp.momentum() + pi0.momentum()).mass();
    _h[1][0]->fill(mKpi);
    if (mKpi < 1.8) _h[1][1]->fill(mKpi);
    mKpi = (Kp.momentum() + pim.momentum()).mass();
    _h[2][0]->fill(mKpi);
    if (mKpi < 1.8) _h[2][1]->fill(mKpi);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 3; ++ix) {
    for (unsigned int iy = 0; iy < 2; ++iy) {
      normalize(_h[ix][iy], 1., false);
    }
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3][2];
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2011_I897848);

} ```