Rivet analyses

title: BABAR_2016_I1409292

Mass spectra in $B^+\to K^+\pi^+\pi^-\gamma$ decays

Experiment: BABAR (PEP-II)

Inspire ID: 1409292

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 93 (2016) 5, 052013

Beams: * *

Beam energies: ANY

Run details: - Any process making $B^+$ mesons, originally $\Upslion(4S)$ decay.

Mass spectra in $B^+\to K^+\pi^+\pi^-\gamma$ decays measured by BABAR. Useful for testing the implementation of these decays

Source code:BABAR_2016_I1409292.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B+ -> K+ pi+ pi- gamma class BABAR_2016_I1409292 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2016_I1409292);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
  declare(ufs, "UFS");
  DecayedParticles BP(ufs);
  BP.addStable(PID::PI0);
  declare(BP, "BP");
  // histograms
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h[ix], 1 + ix, 1, 1);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode = {{321, 1}, {211, 1}, {-211, 1}, {22, 1}};
  static const map<PdgId, unsigned int>& modeCC = {{-321, 1}, {211, 1}, {-211, 1}, {22, 1}};
  DecayedParticles BP = apply<DecayedParticles>(event, "BP");
  // loop over particles
  for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
    int sign = 1;
    if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 4, mode)) {
      sign = 1;
    }
    else if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 4, modeCC)) {
      sign = -1;
    }
    else
      continue;
    const Particle& Kp = BP.decayProducts()[ix].at(sign * 321)[0];
    const Particle& pip = BP.decayProducts()[ix].at(sign * 211)[0];
    const Particle& pim = BP.decayProducts()[ix].at(-sign * 211)[0];
    _h[0]->fill((Kp.momentum() + pim.momentum() + pip.momentum()).mass());
    _h[1]->fill((Kp.momentum() + pim.momentum()).mass());
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(BABAR_2016_I1409292);

} ```