Rivet analyses

Mass spectra in B⁺ → K⁺π⁺π⁻γ 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⁺ → K⁺π⁺π⁻γ decays measured by BABAR. Useful for testing the implementation of these decays

Source code:`BABAR_2016_I1409292.cc`

// -*- 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);

}

Rivet analyses

Mass spectra in B+ → K+π+π−γ decays

Source code:BABAR_2016_I1409292.cc

Mass spectra in B⁺ → K⁺π⁺π⁻γ decays

Source code:`BABAR_2016_I1409292.cc`