Rivet analyses

title: BABAR_2016_I1487722

$\pi^+\pi^+\pi^-$ mass distribution in $B^0\to D^{*-} \pi^+\pi^+\pi^-$

Experiment: BABAR (PEP-II)

Inspire ID: 1487722

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 94 (2016) 9, 091101

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of mass distributions of the pions in the decay $B^0\to D^{*-} \pi^+\pi^+\pi^-$. The data were read from, the plots in the papers and efficiency from the paper applied.

Source code:BABAR_2016_I1487722.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B0 -> D*- pi+ pi+ pi- class BABAR_2016_I1487722 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2016_I1487722);


/// @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(413);
  B0.addStable(-413);
  B0.addStable(423);
  B0.addStable(-423);
  B0.addStable(PID::PI0);
  declare(B0, "B0");
  // histograms
  book(_h, 1, 1, 1);
  // efficiency
  const Estimate1D& ref = refData(2, 1, 1);
  _edges = ref.xEdges();
  _eff = ref.vals();
}

double eff(double mass) {
  if (mass < _edges[0] || mass > _edges.back()) return 0.;
  for (unsigned int ix = 0; ix < _eff.size(); ++ix) {
    if (mass < _edges[ix + 1]) return _eff[ix];
  }
  return 0.;
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode1 = {{-413, 1}, {211, 2}, {-211, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{413, 1}, {-211, 2}, {211, 1}};
  DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
  for (unsigned int ix = 0; ix < B0.decaying().size(); ++ix) {
    int sign = B0.decaying()[ix].pid() / B0.decaying()[ix].abspid();
    if ((sign == 1 && B0.modeMatches(ix, 4, mode1)) || (sign == -1 && B0.modeMatches(ix, 4, mode1CC))) {
      FourMomentum ptotal;
      for (const Particle& p : B0.decayProducts()[ix].at(sign * 211)) {
        ptotal += p.momentum();
      }
      for (const Particle& p : B0.decayProducts()[ix].at(-sign * 211)) {
        ptotal += p.momentum();
      }
      double m = ptotal.mass();
      _h->fill(m, eff(m));
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h;
vector<double> _eff;
vector<double> _edges;
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2016_I1487722);

} ```